9 - BIOMOLECULES

CHAPTER NO.9 BIOMOLECULES

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INTRODUCTION:The chemical analysis of earth’s crust revealed that all the elements present in a sample of earth’s crust are also present in the sample of living tissue.Cytoplasm of cell contains various compounds of biological importance.

These are known as biomolecules.These biomolecules occur in two forms:

1) Inorganic compounds e.g. Mineral, salts and water.

2) Organic compounds e.g. Carbohydrates, proteins, fats, nucleic acids,vitamins, enzymes, hormones, etc.

Organic and inorganic compounds in cytoplasm occurs in 9 : 1 Chemical analysis of biomolecules revealed that protoplasm essentially consists of 25 types of elements divided into 3 categories --

1) MAJOR ELEMENTS : Carbon ( C ), Hydrogen ( H ), Oxygen ( O ),Nitrogen ( N ), Phosphorous ( P ), Sulphur ( S ) form 98% of the weight of protoplasm and called protoplasmic elements.

2) MINOR ELEMENTS: Ca**, Mg **, Na’*, K*, Cl, I, Fe**, etc.

3) TRACE ELEMENTS : Mn**, Co*t, Cu**, Zn**, Mo**, etc.

ANALYSIS OF ELEMENTS IN ORGANIC COMPOUNDS:

For its chemical composition, organic compounds can be analysed by the

following:

a) Grind the living tissue (a piece of vegetable) in trichloroacetic acid in

mortar to obtain a thick slurry.

b) Filter this slurry through a cheese cloth or cotton to obtain filtrate (acid

soluble) and retentate (acid insoluble).

c) The acid soluble fraction represents micro biomolecules of cytoplasm

and acid insoluble fraction as macro biomolecules.

d) Each fraction is subjected to various fractionate techniques to separate

biomolecules.

e) Each fraction is then purified and then its chemical structure and molecular formulae are determined.All the carbon compounds that we get from the living tissue can be called biomolecules; however living organisms also have inorganic elements and compounds in them.

ANALYSIS OF INORGANIC ELEMENTS AND COMPOUNDS

a) Weigh a small amount of living tissue and note down its wet weight.

b) Dry the living tissue and note down its dry weight.

c) Burn the dry tissue to oxidise all the organic compounds to obtain ash

which contains inorganic compounds of calcium and magnesium.

d) Ash or acid soluble fraction is subjected to elemental analysis to know

elemental composition of living tissue in the form of carbon, oxygen,hydrogen, chloride, sodium, potassium, calcium, magnesium; inorganic compounds like NaCl, CaCO3, Phosphates, sulphates, etc.

While analysis four compounds give an idea of the kind of organic and inorganic constituents present in living tissue.

We shall classify these bio-micromolecules as

|. _Monosugars (monosaccharides)

Il. Nucleotide bases

Hl. Amino acids

I¥V. Fatty acids

STRUCTURE OF MONOSUGARS: These are the simplest type of carbohydrates. Chemically, these are formed of C, H, O in the ratio of 1:2:1.General formula for monosaccharides is (CH2O), where n is the no. of

carbon atoms. Monosugars (Monosaccharides) are called sugars as these are

sweet in nature. For example :

1) GLUCOSE : Glucose is a monosaccharide having 6 carbon atoms having aldehyde group at C-1 General formula : CgHi20¢

2) RIBOSE: It is a monosugar with 5 carbon atoms.General formula. Cs5H:0Os

NUCLEOTIDES Nucleotides are building blocks of nucleic acids (DNA and RNA).A nucleotide is formed of three components:

1) Pentose sugar: It is a 5 carbon sugar and is presents as ribose sugar in

RNA and deoxyribose sugar in DNA.

2) Nitrogen base: In two types of nucleic acid, there are 5 types of nitrogen

bases out of which only one base is present in nucleotide. DNA contains A (adenine), G (guanine), C (cytosine) and T (thymine) while RNA contains A,G, C and U (uracil).

3) Phosphate group: Derived from phosphoric acid and present in both DNA and RNA.

Formation of nucleotides: Nitrogen base is linked with pentose sugar at carbon 1 by glycosidic bond. Combination of nitrogen base and a pentose sugar is called nucleoside. When a phosphate molecule attach at C-5

of pentose sugar of a nucleoside, it becomes a nucleotide.

Different nucleotides are adenylic acid, thymidylic acid, guanylic acid,

uridylic acid and cytidylic acid.

Nucleosides are slightly basic in nature and nucleotides are acidic in nature.

Nucleotides are building blocks of both types of nucleic acid.DNA and RNA functions as genetic material.

AMINO ACIDS Amino acids are small molecules made up of C, H, O, N and little S.

Amino acids are organic compounds having amino group (NH:; and acidic group (carboxyl - COOH) on the alpha carbon atom therefore these are calle as alpha amino acid.These are substituted methanes. These are four substituent groups occupying the four valency positions. These are : a hydrogen atom,carboxyl group, amino group and variable side chain (R).Those amino acids which occur in proteins are only of twenty types.

TYPES OF AMINO ACIDS are:

1) Basic amino acids — When amino group is free, it is said to be basic.They contain two amino groups and one carboxyl group. e.g. — lysine and arginine.

2) Acidic amino acids — When carboxyl group is free, it is called acidic amino acid. e.g. — Glutamic acid and aspartic acid. They bear one amino group and two carboxylic groups.

3) Neutral amino acid — They contain only one carboxylic group and one amino group. e.g. — alanine, lysine, valine, etc.

PHYSICAL AND CHEMICAL PROPERTIES OF AMINO ACIDS depends on three functional groups:

1) Amino group

2) Carboxyl group

3) R side chain

ZWITTER IONIC NATURE

A peculiar property of amino acids is their ionisable nature of their -NH2 and COOH group to NH3 and COO by transfer of H atom from COOH to NH2 group. This double charged ionic form of amino acid is called zwitter

ion. It depends upon the pH of the solution.So an amino acid can act as either an acid (proton donor) or a base (proton

acceptor.

FATTY ACIDS & GLYCEROL Fatty acids and glycerol are the building blocks of lipids.

FA are organic molecules made up of long hydrocarbon chains which contain a terminal carboxyl group (-COOH).The hydrocarbon chain (-R group) may be methyl or ethyl or of higher number of CH» group Fatty acids are called Saturated if they bear single bond between the carbon atoms of molecular chain. e.g. — Palmitic acid and stearic acid Unsaturated fatty acids have one or more double bond. e.g. — Oleic acid,

linoleic acid Essential fatty acids are those which can not be synthesized in the body tissues and must be present in the diet. e.g. — Linoleic acid Non-essential fatty acids can be synthesized in body tissues so may or may not be present in diet. e.g. — Palmitic acid A chemical bond between glycerol and fatty acid is called ESTER BOND.Three hydroxyl groups of glycerol molecule can unite with the carboxyl group of three fatty acids to form fat or lipid molecule.Most lipids are esters of glycerol that is why these are called as glycerides.Depending on the number of fatty acid molecules found esterified with glycerol,the fats are called monoglycerides (one FA esterified with glycerol), diglycerides (two FA) and triglycerides (three FA).Triglycerides are also known as neutral fats. These are also known as fats and oils based on the melting point. Oils have lower melting point and hence, remain liquid in winter.

Some lipids have phosphorous and phosphorylated organic compound in them.These are called phospholipids. They are found in cell membrane.Neural tissues have lipids with more complex structure.

PRIMARY AND SECONDARY METABOLITES

Metabolites are those biomolecules which are either utilized in metabolic function

or are synthesized by cellular machinery.

1) Primary Metabolites are found in all the cell types and play known functions in normal physiological process. e.g.: Amino acids,carbohydrates, nucleotides, fats, etc.

2) Secondary metabolites are found only in plant. fungal and microbial cells.

No identifiable function performed in normal physiological processes but is

useful to human welfare. e.g.: Alkaloids, rubber, pigments, essential oils,

antibiotics, etc.

PART: A- VERY SHORT ANSWER TYPE QUESTIONS:

A) MULTIPLE CHOICE QUESTIONS:

1) Organic and inorganic compound in cytoplasm generally occur in the ratio:

a) 8:2

b) 7:2

c) 9:1

d) 9:2

2) Major elements found in protoplasm are:

a) C,H,O,He

b) P,S,H,Ca,K

c) C,H,O,N,P_ q

d) Cl,H, K, Na, O

3) Nucleotides are building blocks of:

a) Acetic acid

b) Nucleic acid

c) Sulphuric acid

d) Amino acid

4) Acidic amino acids contain:

a) 2 amino groups and 1 carboxylic group

b) 1 amino group and 1 carboxylic group

c) 1 amino group and 2 carboxylic group

d) 3 amino group and none carboxylic group

5) Fatty acids and glycerol are building blocks of:

a) Amino acids

b) Lipids

c) Nucleic acid

d) sugars

B. TRUE/FALSE:

1) Palmitic acid and stearic acid are unsaturated.

2) An amino acid can act as either acid or base.

3) Monosaccharides are called sugars as these are sweet.

C. FILL UPS:

a) A chemical bond between glycerol and fatty acid is called .

b) The amino acids which occur in proteins are only of types.

ANSWER KEY: PART-A

A. MCQS:

1) c — Because organic compounds are more abundant than inorganic

compounds.

2) c-—C, H, O, N, P form about 98% of weight of protoplasm so called major

elements.

3) b — Nucleic acids (DNA and RNA) are formed by nucleotides.

4) c -Acidic amino acid has one amino group and two carboxylic groups.

5) b — Lipid; Fatty acids esterify with glycerol to form lipids.

B. TRUE/FALSE

1) False — because palmitic acid and stearic acids are saturated acids as they

have single bond in their carbon atoms.

2) True — because it has both carboxylic group and amino group. When amino

group is free, it is basic and when carboxylic group is free, it is basic.

3) True — Monosaccharides are sweet in taste.

C. FILL UPS:

a) Ester — because many lipids have both glycerol and fatty acids. Lipids are

esters of glycerol.

b) 20 — There are only twenty types of amino acids.

PART: B- SHORT ANSWER TYPE QUESTIONS:

1) What do you mean by biomolecules? Give examples.

2) Define essential and non- essential amino acids.

3) Why oils remain liquid in winter?

4) What are primary and secondary metabolites?

PART: C- LONG ANSWER TYPE QUESTIONS:

1) Write short note on fatty acids and glycerols.

Write a note on nucleotides.

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INTRODUCTION:BIOMACROMOLECULES are the large sized biomolecules of high molecular

weight and are formed by the linking of a number of micro biomolecules commonly

called monomers by specific bond so, are also called polymers (except lipids).

If you represent the chemical composition of living tissue from abundance point of

view and arrange them class wise, we observe that water is the most abundant

chemical in living organisms.

There are four types of bio macromolecules:

a) Proteins

b) Polysaccharides complex Sugars

c)Lipids

d) Nucleic acids

In this assignment we will discuss about proteins only BE are polypeptides.

Proteins are polymers of amino acids which are interlinked by peptide bonds.They are the linear chain of amino acids.These are macro biomolecules of high molecular weight.As there are 20 types of amino acids, a protein is a heteropolymer not a

homopolymer.A homopolymer has only one type of monomer repeating a number of times.

Each polypeptide chain has two specific ends. N Terminus (end with free NH2

group of first amino acid) and C terminus (ends with free carboxyl group of last

amino acid).There are four structural models of proteins:

PRIMARY STRUCTURE- There is linear arrangement of amino acid.

SECONDARY _ STRUCTURE - There is spatial arrangement of amino acid.

FOR EXAMPLE: Keratin

TERTIARY STRUCTURE - Polypeptide chain folded to form three-dimensional globular structure. FOR EXAMPLE: Myoglobin of muscles and all the enzymatic proteins.

QUARTERNARY STRUCTURE - Relative folding of two or more similar or

dissimilar polypeptides upon one another. FOR EXAMPLE: Haemoglobin

Types of protein on the basis of Shape:

Proteins are divided into two categories on the basis of shape, globular and fibrous.

a) GLOBULAR PROTEINS: In these, polypeptide chains are compactly folded to form compact globular shape. FOR EXAMPLE: Egg albumin,

Haemoglobin, etc.

b) FIBROUS PROTEIN: In these, polypeptide chains are extended along one axis and are spirally wound to form fibres. FOR EXAMPLE: Alpha-Keratin of hair, nails, claws; myosin and actin of muscles.

DIETARY PROTEINS (proteins in our food) are the source of essential amino acids.

Therefore, amino acids can be essential or non-essential.

Non-essential amino acids are those which make proteins, carry out many functions

in living organisms.

Collagen is the most abundant protein in animal.Rubisco enzyme is most abundant protein in whole of the biosphere.Types of proteins on the basis of chemical compositions

a) Simple proteins: These proteins are formed of only amino acids. For example:

albumin, histones, etc.

b) Conjugated proteins: In these, proteins are associated with the non proteinaceous compound called prosthetic group which is essential for the biological functioning of protein. For example: casein.

c) Derived proteins: These are products of denaturation or partial digestion of

proteins. For example: Fibrin, Cooked proteins, etc.

PART A- VERY SHORT ANSWER TYPE QUESTIONS:

A) MULTIPLE CHOICE QUESTIONS:

1) The most abundant chemical in living organism is:

a) Protein

b) Water

c) Sugar

d) Nucleic Acid

2) The most abundant protein in animal world:

a) Lignin

b) Rubisco

c) Cellulose

d) Collagen

3) Amino acids in the proteins are interlinked by:

a) Peptide bond

b) Phosphodiester bond

c) Hydrogen bond

d) Glycosidic bond

4) Ahomopolymer has only:

a) Four types of monomers

b) Three types of numbers

c) Two types of more numbers

d) One type of monomer

5) Which of the following proteins help in the transportation of materials?

a) Alpha carotene and collagen

b) Pepsin and trypsin

c) Haemoglobin

d) Myosin and Actin

B) TRUE / FALSE:

1) Dietary proteins are the source of non-essential amino acids

2) Average percentage of protein in the cellular mass is 10 to 15%

3) On the basis of shape, proteins are divided into four categories

C) FILL UPS:

1) Proteins are polymers of

2) Haemoglobin of RBC is transport

ANSWER KEY: PART-A

A) MULTIPLE CHOICE QUESTIONS:

1- b) water average percentage of water in the seller mass is 70 to 90%

2- d) the collagen is most abundant

3- a) peptide Bond in a polypeptide or protein amino acids are linked by

peptide Bond

4- d) one type of monomers there are one type of monomers

5- C) haemoglobin and growth for aemoglobin of RBC is transport of Oxygen and Carbon dioxide and loot transport glucose into cell

B) TRUE / FALSE:

1) False: Dietary Proteins (proteins in our food) are the source of essential amino acids.

2) True

3) False: Proteins are divided into two categories on the basis of shape;

globular and fibrous.

C) FILL UPS:

1) Amino acid

2) Oxygen and Carbon dioxide

PART: B__ SHORT ANSWER TYPE QUESTIONS:

1) What do you mean by biomacromolecules?

2) Name the types of protein on the basis of their structures.

3) Define Homopolymer and Heteropolymer.

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INTRODUCTION:As we have already studied there are four types of BIOMACROMOLECULES, namely Proteins, Polysaccharides, Lipids and Nucleic acids.Each one of them has unique structural properties and varied

functions in our body.

POLYSACCHARIDES Polysaccharides are a long chain of sugars.Polysaccharides, also called glycans; are polymers of more than 10 monosaccharides inter linked by glycosidic bond.On the basis of nature of monosaccharides, polysaccharides are

divided into two categories:

1. HOMOPOLYSACCHARIDES : These types of polysaccharides are formed of only one type of monosaccharides. e.g.

A. CELLULOSE -It is a polymer made up of glucose molecules.It is interlinked by glycosidic bonds.It is found in the cell wall of most algae, all higher plants, certain protista and fungi.As cellulose does not contain complex helices so cannot

hold iodine and qive no colour with iodine.

B. STARCH -Itis also a polymer made up of glucose molecules.It is the STORAGE HOMOPOLYSACCHARIDE found in plants like

potato, corn seeds, cereals, etc.Two types -- Alpha Amylose and Amylopectin

Amylose has glucose molecules linked by (a 1—4) bonds whereas amylopectin has glucose molecules linked by both (a 1—4) and (a 1—6) bonds.

Starch can hold iodine molecules in the helices. So it gives blue

Colour with iodine.

C. GLYCOGEN - It is also a polymer made up of glucose molecules.It is the STORAGE HOMOPOLYSACCHARIDE found in liver cells

and muscles of animal so is called animal starch.Glycogen has glucose molecules linked by both (a 1—4) and (a1—6) bonds.

It gives red colour with iodine.

D. CHITIN Itis a NEUTRAL OMOPOLYSACCHARIDES found in the skeleton of arthropods like crab, prawn, etc. and fungal cell wall.

It is a polymer of N-acetylglucosamine interlinked by glycosidic bonds.

2. HETERO POLYSACCHARIDE:These are formed of two or more types of monosaccharide or their derivatives.They have building blocks of amino Sugars and chemically

modified Sugars.e.g. glucosamine and n-acetylgalactosamine or sugar acids like glucuronic acid, etc.Heteropolysaccharides are more complex than homopolysaccharides.

e.g. MUCOPOLY SACCHARIDES: These are heteropolysaccharides of high molecular weight that are gelatinous functioning inlubrication.e.g. Pectin, Agar- Agar, Hyluronic acid, Keratosulphate, Chondroitin

sulphate, Lignin and Heparin.

A.) Hyaluronic acid - It is a linear acidic hetero polysaccharide found in Synovial fluid of limb joints, around ovum, etc.

B). Peptidoglycans (Murein) - It is found in the cell wall of bacteria and

cyanobacteria. It prevents lysis and osmotic inflow through the cell wall.

It is interwoven network of sugar polymers and amino acids.

It is formed of linear chains of two alternating amino acids; N-acetyl galactosamine and N-acetyle muramic acid.

LET US KNOW WHAT WE HAVE LEARNT!

PART: A- VERY SHORT ANSWER TYPE QUESTIONS :

A) Multiple Choice Questions:

1) On the basis of nature of monosaccharides, polysaccharide are

divided into:

a) 3 categories

b)2categories

c)5categories

d) 7 categories

2) Cellulose is the polymeric polysaccharide made up of:

a) Glucose

b) Fructose

c)Agar

d) Glucosamine

3) Starch is the storage polysaccharide of:

a) Fungi

b)Animals

c) Plants

d) Bacteria

4) It is also called animal starch:

a) Glycogen

b) chitin

c)Peptidoglycan

d) Cellulose

5) N-acetylglucosamine interlinked by glycosidic bond to form:

a) Starch

b)I Inulin

c)Murein

d) Chitin

B) True/False:

1) Polysaccharides are long chains of sugars.

2) Polysaccharides are also called ribosomes.

3) Glycogen is also called plant starch.

c) Fill in the blanks:

1)Inulin is a polymer of

2)Heteropolysaccharides are than polysaccharides.

A)MCQs:

1) B — Two categories i.e. Homopolysaccharides formed only of one type of monosaccharides and eteropolysaccharides

formed of two or more types of monosaccharides.

2) A— Glucose molecules interlinks to form cellulose.

3) C — Starch is found in potato tubers, corn seeds, cereals like rice, wheat, etc. and fruits like banana, mangoes, etc.

4) A-— Glycogen is found in the muscle and liver cells of animals.

5) D — Chitin is the polymer of N-acetylglucosamine.

TRUE/FALSE:

1) T

2) F

3) F

FILL Ups:

1) Fructose

2) More complex

PART: B SHORT ANSWER TYPE QUESTIONS:

1) Why cellulose gives no colour with iodine?

2) Why glycogen is called animal starch?

3) Where peptidoglycans are found and what is their function?

PART: C LONG ANSWER TYPE QUESTIONS:

1) Write a short note on polysaccharides.

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INTRODUCTION

BIOMOLECULES RECAPITULATION:As we have already studied there are four types of BIOMACROMOLECULES,namely Proteins, Polysaccharides, Lipids and Nucleic acids.

Each one of them has unique structural properties and varied functions in

our body.Out of these nucleic acids are of utmost importance.These form the genetic material in organisms.

NUCLEIC ACIDS:Nucleic acids are iopolymers, or large biomolecules, essential to all

known forms of life.Present in living cells that store, encode and transmit genetic data from one generation to another.

serve as the primary information-carrying molecules in cells

HISTORY OF NUCLEIC ACIDS:Nuclein was discovered by Friedrich Miescher in 1869.

In the early 1880s Albrecht Kossel further purified the substance and

discovered its highly acidic properties.

In 1889 Richard Altmann creates the term nucleic acid.In 1938 Astbury and Bell published the first X-ray diffraction pattern of DNA.In 1944 the Avery-MacLeod—McCarty experiment showed that DNA is the

carrier of genetic information.In 1953 Watson and Crick presented the double helical structure of DNA.

1. DNA Deoxyribonucleic acid, more commonly known as DNA, is a complex molecule

It contains all of the information necessary to build and maintain an

organism.Each strand of a DNA molecule is composed of a long chain of monomer nucleotides.It is organized into chromosomes.They are present in the nucleus of the cells.Controls cellular activities.

COMPONENTS OF DNA:DNA is composed of a deoxyribose sugar molecule to which is

attached a phosphate group and one of four nitrogenous bases:two purines (adenine and guanine) and two pyrimidines (cytosine and thymine).

A. DEOXYRIBOSE SUGAR : Deoxyribose, also called d-2-deoxyribose,five-carbon sugar component of DNA

B. NITROGENOUS BASES: DNA has four Nitrogenous Bases which are categorised into two categories.

Guanine always binds to cytosine and adenine always binds to

thymine.Guanine and cytosine share three hydrogen bonds while adenine and thymine always share two hydrogen bonds.

C. PHOSPHATE GROUP: The phosphate group of one nucleotide bonds covalently with the sugar molecule of the next nucleotide.

STRUCTURE OF DNA: The DNA structure can be thought of like a twisted ladder. This

structure is described as a double-helix.

The nucleotides are joined together by covalent bonds between the phosphate of one nucleotide and the sugar of the next, forming a phosphate-sugar backbone from which the nitrogenous bases protrude.

One strand is held to another by hydrogen bonds between the bases; the sequencing of this bonding is specific—i.e., adenine

bonds only with thymine, and cytosine only with guanine.

WATSON & CRICK MODEL OF DNA The structure of DNA, as represented in Watson and Crick's model, is a double-stranded, antiparallel, right-handed helix.A DNA molecule consists of two long polynucleotide chains composed

of four types of nucleotide subunits.

Each of these chains is known as a DNA chain, or a DNA strand.Hydrogen bonds between the base portions of the nucleotides hold the two chains together.

The sugar-phosphate backbones of the DNA strands make up the outside of the helix, while the nitrogenous bases are found on the inside and form hydrogen-bonded pairs that hold the DNA strands together.

Double-stranded DNA is an antiparallel molecule, meaning that it's composed of two strands that run alongside each other but point in opposite directions.

2. RNA STRUCTURE:-Ribonucleic acid (RNA) is a molecule similar to DNA.Unlike DNA, RNA is single-stranded.An RNA strand has a backbone made of alternating sugar (ribose) and phosphate groups.Attached to each sugar is one of four bases--adenine (A), uracil (U),cytosine (C), or guanine (G).

RNA plays a vital role in the synthesis of proteins that mainly involves decoding and translation of genetic code and transcription to produce protein.

There are several different types of RNA and each has a specific function.Messenger RNA - messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a

gene. Ribosomal RNA - It is one of the components of ribosomes that are involved in protein synthesis. Transfer RNA It is essential for the translation of MRNA in

protein synthesis.

LET’S KNOW WHAT WE HAVE LEARNT!

PART A- VERY SHORT ANSWER TYPE QUESTIONS:

A) MULTIPLE CHOICE QUESTIONS:

1. Which one is correct base pairing for DNA molecules?

a. Cytosine — Uracil

b. Thymine — Guanine

c. Thiamine — Adenine

d. Cytosine — Guanine

2. DNAresembles RNA as both have:

a. Ability to replicate

b. Similar sugars

c. Similar Pyrimidine bases

d. Polymer of nucleotides

3. RNA differs from DNA in replacement of thymine with:

a. Uracil

b. Adenine

c. Guanine

d. Cytosine

4. DNA is:

a. Negatively charged

b. Positively charged

c. Neutral

d. None

5. Which type of bonds are present between Guanine and Cytosine:

a. Hydrogen bond

b. Phosphodiester bond

c. lonic bond

d. Both a and b

B) FILLIN THE BLANKS :-

1. Double helical structure is found in .

2. Three pyrimidines are thymine, cytosine and .

3. DNA has instead of uracil.

C) TRUE FALSE :-

1. In a nucleotide, a purine or pyrimidine nitrogenous base is joined by

deoxyribose sugar which is further linked to phosphate.

2. Component of RNA which is involved in protein synthesis is Ribosomal RNA.

3. Most abundant RNA of all is t-RNA.

ANSWER KEY: PART-A

A) MCQ’s:

1. d-Cytosine — Guanine

2. d—Polymers of nucleotides

3. a— Uracil

4. a—Negatively Charged

5. a-—Hydrogen Bond

B) FILL UPS:

1. DNA

2. Uracil

3. Thymine

C) TRUE/FALSE:

1. True

2. True

3. False: Most abundant RNA of all is r-RNA.

PART: B - SHORT ANSWERS TYPE QUESTIONS:

1. Write a note on purines & pyrimidines?

2. Write the chemical composition of DNA?

3. What are main functions of r-RNA & t-RNA?

PART: C- LONG ANSWER TYPE QUESTIONS:

1. Explain the structure of DNA?

2. What do DNA and RNA stands for? Explain different types of RNA?

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The human body is composed of different types of cells, tissues and other complex

organs. For efficient functioning, our body releases some chemicals to accelerate

biological processes such as respiration, digestion, excretion and few other

metabolic activities to sustain a healthy life. These chemicals are called enzymes,

which play pivotal role in all living entities governing all the biological processes.

ENZYME STRUCTURE :-Enzymes are a linear chain of amino acids, which give rise to a three-dimensional! structure. The sequence of amino acids specifies the structure, which in turn identifies the catalytic activity of the enzyme. Upon heating, enzyme's structure denatures, resulting in a loss of enzyme activity that typically is associated with temperature.Compared to its substrates, enzymes are typically large with varying sizes,ranging from 62 amino acid residues to an average of 2500 residues found in fatty acid synthase. Only a small section of the structure is involved in catalysis and is

situated next to the binding sites. The catalytic site and binding site together

constitute the enzyme's active site. A small number of ribozymes exist which serve

as an RNA-based biological catalyst. It reacts in complex with proteins.

ENZYMES CLASSIFICATION :- Enzymes are divided into six functional classes and are classified based on the type of reaction in which they are used to catalyze. The six kinds of enzymes are HYDROLASES, OXIDOREDUCTASES,LYASES, TRANSFERASES, LIGASES & ISOMERASES.

EXAMPLES OF ENZYMES :-Following are some of the examples of enzymes:

Beverages :-Alcoholic beverages generated by fermentation vary a lot based on many

factors. Based on the type of the plant's product, which is to be used and the type of the enzyme applied, the fermented product varies.

For example, grapes, honey, hops, wheat, cassava roots, and potatoes

depending upon the materials available. Beer, wines and other drinks are produced

from plant fermentation.

Food Products :-Bread can be considered as the finest example of fermentation in our

everyday life. A small proportion of yeast and sugar is mixed with the batter for

making bread. Then one can observe that the bread gets puffed up as a result of

fermentation of the sugar by the enzyme action in yeast, which leads to the

formation of carbon dioxide gas. This process gives the texture to the bread, which would be missing in the absence of the fermentation process.

Drug Action :- Enzyme action can be inhibited or promoted by the use of drugs

which tend to work around the active sites of enzymes.

CHARACTERISTICS OF ENZYMES :-Enzymes are two types, simple and complex enzymes.

Produces the required product using the specific substrate.Most of the enzymes are globular proteins and a few are RNA-based molecules.Enhance the speed of biochemical reactions by lowering the activation energy.Enzyme active sites have some sort of charges either it is negative or positive,termed as a nucleophilic character.Simple enzymes are only proteins, while complex enzymes are made up of

protein and cofactors.For biochemical reactions, enzymes are required in very little amount compared to chemical catalysts.Enzymes can be recycled for further reactions.The active site contains less hydrophobic amino acids compared to entire proteins.Most of the enzymes are larger than the substrate so that enzymes fit more tightly around the substrate.

The active site in the enzyme structure is a very smail portion having between 3 to

12 amino acids.The function of enzymes depends on various factors including temperature, pH,and substrate concentration.‘The chemical composition of the active site is important to access the substrate binding and controlling solvent access during the reaction.The enzymatic reaction is very specific.The enzymatic reaction can be inhibited by various inhibitors.The enzyme binds its substrate and forms an enzyme-substrate complex.

Some enzymes catalyze reversible reactions.

Some enzymes need coenzymes or cofactors for the reaction to happen.Enzymes do not change the structure and function of final products once released from their active site.Enzymes are both intracellular and extracellular catalysts.

FUNCTIONS OF ENZYMES :-The enzymes perform a number of functions in our bodies. These

functions are:

1. Enzymes are responsible for the movement of ions across the plasma membrane.

2. They function to reorganize the internal structure of the cell to regulate cellular

activities.

3. They break down large molecules into smaller substances that can be easily

absorbed by the body.

4. They help in generating energy in the body. ATP synthase is the enzymes

involved in the synthesis of energy.

5. Enzymes perform a number of biochemical reactions, like oxidation, reduction,

hydrolysis, etc. to eliminate the non-nutritive substances from the body.

6. Enzymes help in signal transduction. The most common enzyme used in the

process includes protein kinase that catalyzes the phosphorylation of proteins.

LET US KNOW WHAT WE HAVE LEARNT!

PART-A VERY SHORT ANSWER TYPE QUESTIONS :-

MCQ’s:

1) Enzymes are polymers of:

a) Nucleotides

b) Fatty acids

c) Proteins

d) Amino acids

2) Enzymes are essential in our body because:

a) Supply energy

b) Catalyze Biochemical reactions in cell

c) Structural component of the body

d) Coordinate nervous activities of body

3) Enzymes are basically made up of:

a) Nucleic acids

b) Proteins

c) Fats

d) Vitamins

4) Enzymes are sensitive to:

a) pHcharge

b) Light

c) Rainfall

d) Wind velocity

5) Enzymes are different from inorganic catalysts in:

a) Not being used up in reactions

b) Being proteinaceous in nature

c) Having a high diffusion rate

d) Working at high temp

FILL IN THE BLANKS:

1) The enzymes which break down proteins into amino acids are called as .

2) When the enzymes with slightly different molecular structure can also perform the

identical activity, they are called as ;

3) Biochemical reactions are regulated by catalysts called .

TRUE/FALSE:

1) Enzymes are polymers of fatty acids.

2) Enzymes enhance the rate of reaction by increasing the activation energy.

3) Enzymes are essential in our body because these catalyze biochemical reactions in the cell.

ANSWER KEY: PART-A

MCQ’s:

1) d — Amino acids

2) b — Catalyse biochemical reactions in the cells

3) b - Proteins

4) a —pH change

5) b — Being proteinaceous in nature

FILL IN THE BLANKS:

1) Proteases

2) Isoenzymes

3) Enzymes

TRUE/FALSE:

1) False: — These are polymers of amino acids

2) False: Enzymes enhances the rate of reaction by lowering the activation

energy.

3) True

PART-B SHORT ANSWER TYPE QUESTIONS:

Q Why enzymes are considered as biochemical catalysts?

Q2 Whatis the chemical nature of enzymes?

Q3 What are ligases?

PART-C LONG ANSWER TYPE QUESTIONS:

Q1 How enzymes are classified Discuss. Discuss different types of enzymes?

A96

INTRODUCTION:The human body is composed of different types of cells, tissues

and other complex organs. For efficient functioning, our body releases

some chemicals to accelerate biological processes such as respiration, digestion, excretion and few other metabolic activities to sustain a healthy life. These chemicals are enzymes playing pivotal

role in all living entities and governing all the biological processes.

FACTORS AFFECTING ENZYME ACTIVITY :-The conditions of the reaction have a great impact on the activity of the enzymes. Enzymes are particular about the optimum

conditions provided for the reactions such as :-

1. Temperature

2. pH

3. Alteration in substrate concentration, etc.

TEMPERATURE :-Enzyme activities are accelerated with increasing temperatures. As enzymes are functional in cells, the feasible conditions for nearly all enzymes are temperatures that are moderate.

At higher temperatures, given a specific point, there is a drastic decrease in the activity with the denaturation of enzymes. In diluted solutions, purified enzymes denature quickly compared to enzymes in

crude extracts. De-naturations of enzymes can also take place when enzymes are incubated for long durations. More appropriate is to utilize a shorter time duration when it comes to incubation time to gauge the starting velocities of such enzyme reactions. The International Union of Biochemistry suggests the standard assay

temperature to be 30 °C.

pH :-Almost all enzymes are extremely sensitive to pH change.Just some enzymes feasibly operate with pH above 9 and below 5.Most enzymes have their pH - optimum near to neutrality. Any alteration of pH causes the ionic state of amino acid residues to

change in the whole protein and in the active site. The modifications in the ionic state can modify catalysis and substrate binding. The preference of substrate concentration is critical as at lower

concentrations, the rate is driven by concentration, however, at high

concentrations, the rate does not depend on any increase in the concentration of the substrate.Enzymes require an optimum temperature and pH for their action. The temperature or pH at which a compound shows its maximum activity is called optimum temperature or optimum pH,respectively. As mentioned earlier, enzymes are protein compounds.A temperature or pH more than optimum may alter the molecular

structure of the enzymes. Generally, an optimum pH for enzymes is considered to be ranging between 5 and 7.

SUBSTRATE CONCENTRATION :-Enzymes have a saturation point, i.e., once all the enzymes added are occupied by the substrate molecules, its activity will be

ceased. When the reaction begins, the velocity of enzyme action keeps on increasing on further addition of substrate. However, at a saturation point where substrate molecules are more in number than the free enzyme, the velocity remains the same.

TYPE OF SUBSTRATE :-The type of substrate is another factor that affects the

enzyme action. The chemicals that bind to the active site of the enzyme can inhibit the activity of the enzyme and such substrate is called an inhibitor. Competitive inhibitors are chemicals that compete with the specific substrate of the enzyme for the active site. They

structurally resemble the specific substrate of the enzyme and bind to

the enzyme and inhibit the enzymatic activity. This concept is used

for treating bacterial infectious diseases.

SALT CONCENTRATION :-Changes in salinity: Adds or removes cations (+) & anions (-

Disrupts bonds, disrupts the 3D shape

Disrupts attractions between charged amino acids Affect 2° & 3° structure

Denatures protein Enzymes intolerant of extreme salinity.required for the protein's biological activity. Many enzymes require

co-factors to function properly. Co-factors can be considered "helper molecules” that assist enzymes in their action.Co-factors can be ions or organic molecules (called Co-enzymes).Organic co-factors are often vitamins or are made from vitamins. Small quantities of these vitamins must be consumed in order for our enzymes to function correctly.

MECHANISM OF ENZYME ACTION :-Many cofactors will sit in the enzyme active site and assist the binding of the substrate. An inactive enzyme without the cofactor

is called an apoenzyme, while the complete enzyme with cofactor is called a holoenzyme.

Let us know What we have Learnt!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

MCQ’s:

1) Which of the following factors can influence enzyme activity?

a) High temperature

b) pH

c) Subtrate concentration

d) All of these

2) What would happen to the rate of enzyme controlled reactions for every 10°C rise in temperature?

a) The rate doubles itself

b) Decrease by half

c) No effect

d) First increase then decrease

3) At temperature near freezing point, the enzymes are:

a) Activated

b) Inactivated

c) Denatured

d) Slightly inactivated

4) Combination of apoenzyme and co-enzyme produces:

a) Prosthetic group

b) Enzyme subtrate complex

c) Enzyme product complex

d) Holoenzyme

5) An organic substance bound to an enzyme and essential for its activity is called:

a) ApoEnzyme

b) Isoenzyme

c) lIsoenzyme

d) Holoenzyme

FILL IN THE BLANKS:

1) Enzymatic activity stops due to of enzymes at very high

temperature.

2) A Compound with almost similar structure to the substrate

concentration act as a .

3) The molecules on which enzymes act are known as :

TRUE/FALSE:

1) Biochemical reactions are regulated by catalysts called

carbohydrates.

2) Enzymes are also called biocatalysts.

3) Enzymes work best at body temp.

ANSWER KEY: PART -A

MCQ’s:

1) d-—High temp, pH, Substrate concentration, affect enzyme activity.

2) a-—with 10°C rise in temperature rate of reaction doubles itself.

3) b-—Inactivated- Enzymes work best at body temp.

4) d—Holoenzyme- Combination of coenzyme and apoenzyme produce holo enzyme.

5) ¢—Coenzyme- is essential for an enzyme's activity.

FILL IN BLANKS:

1) Denaturation - at very high temp. enzymes get denatured.

2) Competitive inhibitor - Structural similarities between the substrate & inhibitor enables it to compete with substrate for binding to the active site of the enzyme.

3) Substrate — The substrate attaches to the enzyme at its active sites to form

enzyme substrate complex.

TRUE/FALSE:

1) FALSE - Biochemical reactions are regulated by enzymes.

2) TRUE - The enzymes speed up the biochemical reactions taking place in the

body.

3) TRUE-Freezing makes enzymes inactive & high temp. denatures them

permanently.

PART-B SHORT ANSWER TYPE QUESTIONS:

Qi. With the increase in substrate concentration rate of reaction increase to

some extent which is not exceeded further by any rise by any rise in

substrate. Why?

Q2, How do change in temperature the enzyme activity?

Q3, What is meant by competitive inhibitor?

PART-C LONG ANSWER TYPE QUESTION:

Qi. Discuss the factors those effect enzyme activity?

A97

RECAPITULATION:In this chapter of “Biomolecules”, we learnt about;

1) Biomolecules definition, chemical composition of biomolecules,diagrammatic representation of smail molecular weight organic compounds in living tissues.

2) Primary and secondary metabolites.

3) Biomolecules, like proteins, polysaccharides, Nucleic acids their structure and functions.

4) Enzymes, definition various chemical reactions, how do enzymes bring

about high rate of chemical conversions. Factors affecting enzyme activity.

5) Classification and nomenclature of enzyme and definition of co-factors and

their role in catalytic activity of enzyme.

“LET US KNOW WHAT WE HAVE LEARNT!”

PRACTICE QUESTIONS WITH SOLUTION (N.C.E.R.T)

Q. 1. What are Macromolecules? Give Examples.

Ans: 1.Macromolecules are the biomolecules that are formed by the polymerization of large number of micromolecules. Their molecular mass is more than 800 daltons (Da). Macromolecules are found in colloidal state in the intercellular fluid due to their insoluble nature. e.g. - Proteins, Carbohydrate,Lipids.

Q. 2. Illustrate Glycosidic, Peptide and Pospho-Diester bond.

Ans:2. GLYCOSIDIC BOND -The bond between the individual monosaccharide

is called a Glycosidic linkage. This bond is formed between two carbon atoms of

two adjacent monosaccharide units.

PEPTIDE BOND - It is a covalent bond. The amino acids in proteins are linked to

one another through peptide bonds. It is formed between the carboxyl group

(COOH) of one amino acid and amino group (NH2) of the adjacent amino acid,

by removal of one molecule of water.

PHOSPHO-DIESTERBOND: The bond between two successive sugar molecules of different Polynucleotides through a molecule of phosphate... It is a strong covalent bond formed between two adjacent sugar groups and phosphate. These are the bonds that form the -sugar—phosphate—sugar--- backbone of the nucleic acid.

Q. 3. What is meant by tertiary structure of proteins?

Ans: 3. It is the structure that forms when the secondary coiled polypeptides bend

and fold to produce a hollow, woolen ball like structure. It is folded such that the

functional side groups appear on the surface, by coming together of polar regions of specific amino acids while the inactive side groups are formed inside.

4. Find and write down the structure of ten interesting small molecular

weight Biomolecules. Find if there is any industry which manufactures the

compounds by isolation. Find out who are the buyers?

Ans:4. Small sized biomolecules having low molecular weights are called micro-

biomolecules. These include amino acid, mono sugar, triglycerides,phospholipids, Choloestrol, Nitrogen bases, Nucleosides and Nucleotide etc.

Q5. Proteins have primary structure. If you are given a method to know which amino acid is at either of two termini (ends) of a protein, can you connect this information to parity or homogeneity of a protein?

Ans:5. Yes, if we are given a method to know the sequence of proteins, we can

connect this information to the parity of protein. It is known that accurate

sequence of a certain amino acid is very important for the functioning of the

protein. If there is any change in the sequence, it would alter its structure.

Thereby altering the function if we are provided with the method to know the

sequence of the unknown protein, then using this information, we can determine

its structure and compare it with any of the known correct protein sequence. Any

change in the sequence can be linked to the parity or homogeneity.

Q.6. Find out and make a list of proteins used as therapeutic agents. Find

other application of proteins (Cosmetic etc.)?

Ans:6. A number of proteins are used as therapeutic (related to healing of a

disease) agents are as follows:

A) Thrombin and fibrinogen — They help in blood clotting.

B) Antigen (Antibody) — It helps in blood transfusion.

C) Insulin- It helps in maintaining blood glucose level in body.

D) Renin — It helps in Osmoregulation.

E) Rhodopsin, lodopsin — These are the visual pigments.

F) Keratin—Protective protein.

G) Haemoglobin—Transport protein in R.B.C.

Proteins are also commonly used in manufacture of cosmetics, and act as

biological buffers to maintain proper pH of the protoplasm. Monellin and Brazzein are the sweet proteins present in Berries.

Q.7. Explain the composition of Triglycerides?

Ans:7. Trigiycerides are glycerides which are formed from single molecule of

glycerol. esterified with the three fatty acids. It is mainly present in vegetable

oil and animal fats.

The general chemical formula of triglycerides is:

Where R, R‘ and R” are fatty acids. These three fatty acids can be same or different.

Q.8. Can you describe what happen when milk is converted into curd or Yoghurt from your understanding of proteins?

Ans: 8. Proteins are macro molecules formed by the polymerization of amino

acids. Structurally proteins are divided into four levels;

a) Primary structures - it is the linear sequence of amino acid in a

polypeptide chain.

b) Secondary structure — The polypeptides chain is coiled to formed a three

dimensional structure.

c) Tertiary structure — The helical polypeptides chain is further coiled and

folded to form a complex structure.

d) Quaternary structure — More than one polypeptide chain is assembled to

form a quaternary structure.Milk has many globular proteins. Milk is inoculated with curdling bacteria Streptococcus lactis to form curd. Lactic acid produced by these

bacteria, denatures the proteins present in milk, thus converting globular

proteins into fibrous proteins. Therefore by the process of denaturation, the

secondary and tertiary structures of protein are destroyed and form a reticulum

to hold milk fat and other ingredients to produce curd or yogurt.

Q.9. Can you attempt building models of biomolecules using commercially

available atomic models (ball and stick models)?

Ans:9. Ball and stick models are 3D molecular models that can be used to

describe the structure of Biomolecules. In ball and stick model, the atoms are

represented as ball whereas the bonds that hold the atoms are represented

as a stick. Double and triple bonds are represented by springs that form

covered connection between the balls.

The size and colour of various balls are different and are depicted the relative

size of the atoms. It is most fundamental and common model representing bio

molecular structure.

In the above Ball and stick model of D-glucose, the oxygen atoms are represented by reds balls, the hydrogen atoms are represented by blue balls and

carbon atoms are represented grey balis.

Q.10. Attempt Titrating an amino acid against a weak base and discover the

number of dissociating (lonizable) functional groups in an amino acid.

Ans10. Titrating a neutral or basic amino acid against a weak base will dissociate only one functional group, whereas titration between acidic amino acid and a weak acid will dissociate two or more functional groups.

Q.11. Draw the structure of amino acid Alanine?

Ans: 11. STRUCTURE OF ALANINE

Q.12. What are gums made of? Is Fevicol different?

Ans:12. Gums are water soluble, sticky and solidifyingheteropolymers. Gums are

Hetro-polysaccharides. They are made from two or more different types of

Monosaccharide. They are formed from breakdown of plant cells, especially their

pectin containing regions. On the other hand, fevicol is polyvinyl alcohol (PAV)

glue. It is not polysaccharide. It is synthetic resin which not soluble in water.

Q.13. Find out the qualitative test for proteins fats and oils, amino acids and

test any fruit juice, saliva, sweat and urine for them.

Ans: 13.a) A qualitative test for protein is the Xanthoproeic test, when urine is tested

for protein. A yellow precipitate confirms the presence of protein in it.

b) The qualitative test for fats is emulsification test. In this test the

experimental material in water forms emulsion, confirms the presence of

fats.

c) The qualitative test for oils is the paper test. The experimental material is

put on a paper. If oil marks are left, the presence of oil confirmed.

d) The qualitative test for amino acid is ethyl alcohol, ninhydrin and isopropyl alcohol test. The development of a deep blue colour indicates the presence of ammonia, primary/secondary amines, or amino acids in the analyte.

Q.14. Find out how much cellulose is made by all the plants in the biosphere and compare it with how much of paper is manufactured by man and hence what is consumption of plant material by man annually .What is loss of vegetation?

Ans:14. Paper is made up of pulp of wood which is mainly constituted by

cellulose. The cellulose is a polymer of glucose molecules joined together.

About 85 billion tonnes of cellulose is formed annually in the biosphere

.Paper manufacturers consume 0.5 billion tonnes of wood. The increase in

consumption of wood has led to a great loss in vegetation.

Q.15. Describe the important properties of enzymes.

Ans:15. Enzymes are proteinaceous substances which are capable of catalyzing chemical reactions of biological origin without themselves undergoing any change .They are commonly called as biocatalysts.

The properties of enzymes are as follow: —-

a) Enzymes are high molecular weight macromolecules and are proteins by

nature.

b) An Enzymes are active within a narrow range of temperature. The temperature at which an enzyme is most active is called the optimum temperature.

c) Every enzyme has an optimum pH at which it is maximum active.

d) Enzymes are substrate specific i.e., one enzyme catalyzes only a particular

substrate.

e) Every enzyme has specific sites called active sites for binding a substrate.

f) Enzymes activity is sensitive to certain chemicals called inhibitors or

modulators.

g) Enzymes are generally hydrophilic colloids.

A98

INTRODUCTION:DNA Deoxyribo Nuclieic Acid and RNA is Ribo Nucleic Acid.Both are macromolecules which are insoluble fractions of any living tissue.DNA and RNA are nucleic acids.

CHARACTERISTICS OF DNA AND RNA:

1. Nucleic acids are polymeric compounds of nucleotides so called polynucleotides.

2. A polynucleotide chain is formed by interlinking of large number of

nucleotides by phosphodiester bonds.

3. The bond between sugar and phosphate molecule is called ester, while

the linking of phosphate group to two sugar molecules is called

Phosphodiester Bond.

4. Backbone of nucleic acid is formed of alternating arranged phosphate and

pentose sugar molecules while nitrogen bases “stick out” inward from

pentose sugar of backbone.

5. Each nucleic acid chain has two specific ends 5 ' end is with free -OH

group at 5’ carbon of terminal nucleotide. 3’ end is with free -OH group at 3’

end of terminal nucleotide.

6. James Watson and F.C.H proposed the most accepted model of DNA in

1953.

MAIN POSTULATES OF DNA MODEL:

1. It is formed of two right handed Polynucleotides chains.

2. In DNA four types of deoxyribonucleotides are: d-AMP, d-GMP, d-CMP,d -TMP.

3. Each Polynucleotide chain has specific polarity with two specific ends.

4. There is specific base pairing between the nitrogen bases of two chains

Adenine always pair with Thymine with Double Bond A=T,Cytosine always pairing with Guanine by Triple Bond G=C.

5. DNA helix completes one turn by every 3.4nm.

6. Each spiral has 10 Nucleotide.

7. DNA molecules has diameter of about 20 A°

8. DNA has shallow groove of about 12 A° and major grooves about 22 A°

across.

FEATURES OF RNA ANDITS TYPES:

1. RNA is mainly present in free form in cytoplasm.

2. RNA acts as Genetic material, in all plants viruses and some bacteriophages.

3. Itis single stranded mixed polymer of ribonucleotides.

4. lts nucleotides consists of Ribose sugar, Nitrogen base (Adenine, Uracil,

Guanine and Cytosine) and phosphate.

5. RNA is mainly of THREE types;

a) Massenger RNA (m-RNA)

b) Ribosomal RNA _ (r-RNA)

c) TransferRNA (t-RNA)

LET US KNOW WHAT WE HAVE LEARNT!

PART: A-— VERY SHORT ANSWER TYPE QUESTIONS:

A. MULTIPLE CHOICE QUESTIONS:

Q1. In the double helix model of DNA how far is each base pair from the next

base pair?

(a) 3.4nm

(b)0.34nm

(d)34nm

Q2. DNA Model was given by?

(a) Mande

(b) Watson and Crick

(d) Berzelious

Q3. Nucleic acids are?

(a) Polypeptides

(b)Polyimides

(c)Polynucleotides

(d) Polysacchardies

Q4. What type of sugar does DNA contains?

(a)Ribose

(b)3’ Deoxyribose

(d) 5’ Deoxyribose

Q5. How many distinct components does each nucleotide contain?

(a)2

(b) 3

(d) 4

B. TRUE AND FALSE:

Q 1. DNA serves as genetic material for Eukaryotes.

Q 2. Thymine nitrogen base is not present in DNA.

Q 3. Adenine and Thymine bonded together with double hydrogen bond.

C. FILL IN THE BLANKS:

Q 1. Full form of RNA is ;

Q2.InRNA_____ nitrogen base is present instead of Thymine.

ANSWER KEY: PART-A

A. MULTIPLE CHOICE QUESTIONS:

Q 1. (b) 0.34nm

Q2.(b) = Watson and Crick

Q 3. (c) Polynucleotides

Q 4. (c) 2 Deoxyribose

Q 5. (b) 3 (Deoxyribose sugar, Phosphate and nitrogen base)

B. TRUE OR FALSE:

Q 1. True

Q 2. False; There are four nitrogen bases present in DNA:A- Adenine, T- Thyamine, G-Guanine and C-Cytosine.

Q 3. True

C. FILLIN THE BLANKS:

Q 1. Ribose Nucleic acid

Q 2. Uracil

PART: B— SHORT ANSWER TYPE QUESTIONS:

Q 1. Who discovered the double helix structure of DNA.

Q 2. What are the four nitrogen bases of DNA.

Q 3. What does the Nucleotide consist of?

PART: C -LONG ANSWER TYPE QUESTIONS:

Q 1. Draw and explain the structure of DNA.

A99

RECAPITULATION:Biomolecules are chemical compounds found in living organism. They

include organic and inorganic compounds. The collection of various types

of biomolecules of a cell collectively forms cellular pool. These biomolecules occurs in two forms:

1. Inorganic Compounds - e.g., Mineral, salt and Water.

2. Organic Compounds - e.g., Carbohydrate, Proteins, Fats, Nucleic Acids.

Molecular weight of biomolecules found in the acid soluble pool ranges

from 18 to 800 Dalton (Da). Tney are Bio micromolecules.The acid insoluble retention contains chemicals with large molecular

mass of more than 800 Daltons (Da). They are Bio macromolecules.On the basis of this, biomolecules are of two types;

1. Biomicromolecules — e.g. Amino Acids, Lipids, Sugars, Nirtogen bases.

2. Biomacromolecules — e.g. Proteins, Polysaccharides, Lipids,Nucleic Acids.

BIOMICROMOLECULES:

AMINO ACIDS Amino acids are small molecules made up of Carbon, Hydrogen, Oxygen,

Nitrogen and little Sulpher. Amino acids are organic acids having a carbonyl group (COOH) with an amino group (NH) on the alpha carbon atom. The carboxyle group is responsible for giving acidic properties

whereas amino group attributes basic ones; 20 amino acids are used in

protein synthesis. Amino acids are of 3 types;

1) Acidic amino Acids — e.g. Glutamic acid.

2) Basic amino Acidic — e.g. Lysine.

3) Neutral amino acids - e.g. Valine.

Amino acids can also be classified as follows:

1) Essential Amino Acid - They cannot be synthesized by the body

and should be supplied through diet. e.g., Lycine, Leucine,typtophan etc.

2) Non-Essential Amino Acid - They can be synthesized by the body.E.g., Glycine, Serine, Arginine etc.In amino acids — NH & COOH have lonizable nature. If both -NH &

COOH are lonizable, it is called Zwitter ion.

Sugar is sweet and water soluble Carbohydrates. They are formed of C,

H and O in the ratio of 1:2:1.e.g., Glucose, Ribose etc.

NITROGEN BASES These are the nitrogen containing cyclic compounds found in nucleicacids.They are of two types;

1) PURINES - e.g. Adenine (A), Guanine (G).

2) PYRIDINES — e.g. Cytosine(C), Thymine (T), Uracil (U).

BIOMACROMOLECULES:These are large sized biomolecules of high molecular weights. These are formed by the linking of a number of microbiomolecules commonly called

monomers. They are of four types;

1. Proteins

2. Polysaccharides

3. Lipids

4. Nucleic Acids

PROTEINS The term Proteins are coined by J.berzelius (1838) from greek word

‘Proteious”. Proteins are polymers of amino acids interlinked by peptide bond.

Most diverse biomolecules as any one of 20 amino acids may occurs at any point in modified form so are heteropolymer compounds.

Four Structural Models of proteins:

POLYSACCHARIDES Polysaccharides are also called glycans formed of more than 10

monosaccharides linked by glycosidic bonds.

General Formula of Polysaccharide - CeéHi00s.Polysaccarides are divided into two categories;

1) Homopolysaccharides - These are formed of only one type monosaccharides. e.g., Cellulose, Starch, Glycogen.

2) Heteropolysaccharides - These are formed of two or more types of monosaccharides e.g. Chitin ,Peptidoglycans

These are formed of fatty acids and alcohols like Glycerol. Fatty acids are lipids with a hydrocarbon chain (R-Group) ending in COOH

group.

TYPES OF LIPIDS;

1. Saturated Fatty Acids - They have C-C Bonds and no double or triple bonds between carbon atoms. E.g., Palmitic acid.

2. Unsaturated Fatty Acids - They have one or more double and triple bohds.

These are polymeric compounds of nucleotides. Each nucleotide is formed of three compounds.

1) Pentose sugar - These are of two types namely Ribose & Deoxyribose.

2)Nitrogen bases containing heterocyclic ring carbon compounds.These are of two types;

a) Purine (Double ring structure) - Adenine, Guanine.

b) Pyrimidine (Single ring structure) - Thymine. Cytosine, Uracil.

3)Phosphate Group:

TYPES OF NUCLEIC ACIDS:

1. DNA

2. RNA

ENZYMES Enzymes are water soluble colloidal organic macrobiomolecules which

are wholly or partially proteinaceous in nature.Buchner gave the term ‘Enzyme’ from two Greek words en - in and

zyme yeast so enzyme means ‘inside the yeast’.

PROPERTIES OF ENZYMES;

1) Enzymes are proteinaceous in nature.

2) Enzymes are biological in origin.

3) These act as biocatalysts.

4) Enzymes are temperature specific. Active at a specific temperature.

5) Enzyme is required in micro amount as are used again and again.

CO-ENZYMES These are non — proteinaceous constituents of compound enzymes,which are associated with the proteinous APOENZYME of the enzymes and are essential for the catalytic activity of the HALOENZYMES.

LET US KNOW WHAT WE HAVE LEARNT!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

MULTIPLE CHOICE TYPE QUESTIONS:

Q1. Ester linkage occurs in?

(a) Proteins

(b) Lipids

(d) Carbohydrate

Q2.Which of the following is not conjugated proteins?

a) Peptone

b) Glycoproteins

c) Chromoproteins

d) Lipoproteins

Q3. A protein which lacks a metal is?

(a) Glycoproteins

(b) Haemoglobin

(d) Cyto chrome

Q4. Which of following biomolecules are not strictly macromolecules?

(a) Lipids

(b) Nucleic acids

(d) Polysaccharides

Q5. The naturally occurring form of amino acids in proteins?

(a) L-amino acids only

(b) D-amino acid only

(d) None of these

Q6. The most common monomer of carbohydrate is?

(a) Sucrose

(b) Fructose

(d) Glucose

Q7. An enzyme /proteins are formed by chemically bonding together?

(a) CO2

(b) Lipases

(d) Amino acids

Q8. Double hydrogen bond occurs in DNA between?

(a) Adenine and Guanine

(b) Thymine and Cytosine

(d) Uracil and Thymine

Q9. Glycogen is a Homopolymer made up of?

(a) Glucose units

(b) Galactose units

(d) Ribose units

Q10. Which one of following is a non-reducing carbohydrate?

(a) Maltose

(b) Sucrose

(d) Ribose- 5 -phosphate

TURE OR FALSE:

Q1. Amino acids can be acidic, basic or neutral.

Q2. Proteins are one of most diverse molecules of cell.

Q3. DNA has uracil instead of thymine.

FILL IN THE BLANKS:

Q1.Fatsaremadeupof_—s and__.

Q2. Double helical structure is found in ;

ANSEWER KEY: PART-A

MULTIPLE CHOICE TYPE QUESTIONS:

Q1. (b) Ester linkage are key components of molecules called lipids.

Q2. (a) Peptones are linear chains of amino acids, do not contain other molecules.

Q3. (a) Glycoproteins contains oligosaccharides chain.

Q4. (a) Lipids are macromolecules but obtained under macromolecular fractions due to their insoluble nature in the aqueous medium of

a cell.

Q5. (a) All naturally occurring amino acids consist of L-amino acid. The absolute stereochemistry is related to L-glyceraldehydes.

Q6. (d) Glucose is the simple 6- carbon molecule mostly made by plants and green algae during photosynthesis.

Q7. (d) Because proteins are basically polymers of amino acids.

Q8. (c) Because Adenine pairs with Thymine by two hydrogen bonds.

Q9. (a) Glycogen is branched polymer of glucose consist of alpha D

glucose units.

Q10. (b) Because chemical structure of sucrose doesn’t allow certain

organic compounds to form Hemiacetal. (form by addition of an alcohol to an aldehyde or ketone)

TRUE OR FALSE:

Q1. True

Q2. True

Q3. False: RNA has Uracil instead of Thymine.

FILL IN THE BLANKS:

Q1. Fatty Acids, Glucerol

Q2. DNA

PART:B SHORT ANSWER TYPE QUESTIONS:

Q1. What is peptide bond?

Q2. What is a nucleotide?

Q3. Give examples of essential amino acids.

PART:C LONG ANSWER TYPE QUESTIONS:

Q1. Define enzymes? Write their properties.

Q2. Write short note on nucleic acids.

Plus One

Friday, 5 February 2021

Chapter 9 Biomolecules

Chapter 9 Biomolecules

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