biomolecules

Question 1

glycosidic linkage

Answer 1

The two monosaccharides are joined together by an
oxide linkage formed by the loss of a water molecule. Such a linkage
between two monosaccharide units through oxygen atom is called
glycosidic linkage.

Question 2

invert sugar

Answer 2

• Sucrose is dextrorotatory but after hydrolysis gives
  dextrorotatory glucose and laevorotatory fructose.
• Since the
  laevorotation of fructose (–92.4°) is more than dextrorotation of
  glucose (+ 52.5°), the mixture is laevorotatory.
• Thus, hydrolysis of
  sucrose brings about a change in the sign of rotation, from dextro
  (+) to laevo (–) and the product is named as invert sugar.

Question 3

maltose comprises of

Answer 3

two
alpha-D-glucose units

Question 4

lactose (milk sugar)

Answer 4

composed of beta-D-galactose and beta-D-glucose

Question 5

starch is found in

Answer 5

cereals, roots, tubers and some vegetables.

Question 6

starch is a polymer of

Answer 6

alpha glucose

Question 7

glycogen is present in

Answer 7

liver, muscles and brain
and in yeast and fungi

Question 8

importance of carbohydrates.

Answer 8

• Carbohydrates are used as storage molecules as starch in
  plants and glycogen in animals.
• Cell wall of bacteria and plants is
  made up of cellulose.
• We build furniture, etc. from cellulose in the form of wood and clothe ourselves with cellulose in the form of cotton fibre. They provide raw materials for many important industries like textiles,
  paper, lacquers and breweries.

Question 9

Two aldopentoses ___________ are present in nucleic acids.

Answer 9

D-ribose and 2-deoxy-D-ribose

Question 10

peptide linkage

Answer 10

Chemically, peptide linkage is an amide formed between–COOH group and –NH2
group. The reaction between two molecules of
similar or different amino acids, proceeds through
the combination of the amino group of one molecule
with the carboxyl group of the other. This results in
the elimination of a water molecule and formation of
a peptide bond –CO–NH–.

Question 11

complete hydrolysis of dna (or rna) produces

Answer 11

Complete hydrolysis of DNA (or RNA) yields a pentose sugar, phosphoric
acid and nitrogen containing heterocyclic compounds (called bases).

In
DNA molecules, the sugar moiety is -D-2-deoxyribose whereas in
RNA molecule, it is -D-ribose.

Question 12

vitamins

Answer 12

They are generally regarded as organic compounds
required in the diet in small amounts to perform specific
biological functions for normal maintenance of optimum growth and health of the organism.

Question 13

nucleoside

Answer 13

A unit formed by the attachment of a base to 1 position of sugar is
known as nucleoside.

Question 14

nucleotide

Answer 14

when nucleoside is linked to phosphoric acid 5th position of sugar moiety is called nucleotide

Question 15

Nucleotides are joined together by ___________between
5 and 3 carbon atoms of the pentose sugar.

Answer 15

phosphodiester linkage

Question 16

DNA fingerprinting is now used

Answer 16

(i) in forensic laboratories for identification of criminals.

(ii) to determine paternity of an individual.

(iii) to identify the dead bodies in any accident by comparing the DNA’s of parents or
children.

(iv) to identify racial groups to rewrite biological evolution.

Question 17

The two strands in DNA are not identical but are complementary. Explain.

Answer 17

Two
nucleic acid chains are wound about each other and held together
by hydrogen bonds between pairs of bases. The two strands are
complementary to each other because the hydrogen bonds are
formed between specific pairs of bases. Adenine forms hydrogen
bonds with thymine whereas cytosine forms hydrogen bonds
with guanine.

Question 18

primary structure of nucleic acids

Answer 18

Information regarding the sequence of nucleotides in the chain
of a nucleic acid is called its primary structure.

Question 19

Nucleic acids
secondary structure

Answer 19

double strand helix structure for DNA
Two
nucleic acid chains are wound about each other and held together
by hydrogen bonds between pairs of bases.