NCERT Solutions Macromolecules :Structure and functions

Question 1
Write the differences between DNA and RNA?


1. RNA is a single stranded structure.
1. DNA is a double stranded structure
2. It stand for ribonucleic Acid
2. It stands for deoxyribose value Acid
3. It has ribose Sugar
3. It has deoxyribose sugar
4. It is unstable
4. It is stable
5. It is of three types MRNA, RNA, RNA
5. It has 5 forms
6. Nitrogenous bases are
i) Adenine
ii) Guanine
iii) Uracil
iv) Cytosine

6. Nitrogenous bases are –
i) Adenine
ii) Guanine
iii) Thymine
iv) Cytosine

Question 2
Name one protein and indicate its location for each of the following group :
(a) Structural protein
(b)Nutritional protein
(c) Enzyme
(d) Defence
(e) Contraction
(a) Structural protein – keratin; in hair tissues
(b)Nutritional protein –casein; In milk
(c) Enzyme – Insulin; Pancreas
(d) Defence - Antibodies
(e) Contraction – actin, Myosin

Question 3
Differentiate between D-sugar and L-sugar.
It is abundant in nature D-sugar is naturally occurring.
It is less abundant in nature L-sugar is synthetic or made in laboratory.
If the OH-group on the bottom chiral centre points to the right it is referred to as D-Sugar
If the OH-on the bottom chiral centre points to the left, then the sugar is L-sugar.
Structure of D-sugar

Structure of L-sugar

Question 4
What are the main conformations of DNA and which predominates the natures?
The main conformations of DNA are :
(a) A-DNA
(b) B-DNA
(c) Z-DNA
B-DNA conformations predominates the most

Question 5
Give three reasons to explain enormous catalytic flower of enzymes.
(a) A major group of protein are enzymes which are biocatalysts.
(b)Even a simple reaction like dissolution of $CO_2$ does not take place without enzyme.
(c) An enzyme is usually a large molecule which binds to its substrate. Region where substrate bind to the enzyme is known as active site.
(d) Once substrate diffuses into active site in the enzyme substrates. Molecule are correctly oriented so that group are easily transported leading to product formation.
(e) Substrate are also distorted by binding to the enzyme active site and this causes certain bonds to form which leads to product formation.
(f) An enzyme is made of a variety of amino acid residues and some of these can contribute to acid-base catalysis at same site.

Question 6
List three vitamin and their co-enzyme.
Vitamin B1 (Thiamine) – Thiamine Pyrophosphate
Vitamin B2, (Riboflavin) – Flavin adnine dimucleotide (FAD)
Vitamin B3 (Niacin) – Nicotinamide adenine (NAO+) Nicotinamide adenine dinucleotide phosphate (NADP+)

Question 7
Write the strategy used in N-terminal to C-terminal sequencing.
Sequantors are machines which chemically label the N-terminal amino acid of a polypeplide release specifically label amino acid residue leaving the rest of the protein shortened by one amino acid. The labeled amino acid is identified by chromatographic technique. This procedure is repeated as many times as the number of residue protein contain

Question 8
Indicate any one disease caused by mutant protein.
Sickle all Anaemia

Question 9
How do enzyme differ from inorganic catalysts?

Inorganic catalysts.
They are specific in nature for example –
The enzyme which catalyzes the hydrolysis of protein cannot catalyze the hydrolysis of nucleic acid.

They are relatively non-specific in nature. For example- finely divided platinum is used in the industrial process to make sulphuric acid and ammonia.

They can work at ordinary room temperature and normal pressure conditions
They require several atmospheres of pressure and temperature exceeding 5000C.

Question 10
Describe various conditions required for enzyme activity.
Conditions required are –
(i) ordinary room temperature (250C)
(ii) Normal PH
(iii) Normal atmospheric conditions

Question 11
Describe an international unit of enzyme actively.
An international unit (IV) is the catalytic power of enzyme which can catalyze 1u mole of substrate to product in ordinary room temperature usually taken 250C.