Chapter-14 Biomolecules

Write the structures of fragments produced on complete hydrolysis of DNA.
How are they linked in DNA molecule? Draw a diagram to show pairing of
nucleotide bases in double helix of DNA.

Explain the terms primary and secondary structure of proteins. What is the
difference between α-helix and β-pleated sheet structure of proteins?

Carbohydrates are essential for life in both plants and animals. Name the
carbohydrates that are used as storage molecules in plants and animals, also
name the carbohydrate which is present in wood or in the fibre of cotton
cloth.

Write the reactions of D-glucose which can’t be explained by its open-chain
structure. How can cyclic structure of glucose explain these reactions?

Match the following enzyms given in Column I with the reactions they catalyse
given in Column II.
Column I (Enzymes) Column II (Reactions)
(i) Invertase (a) Decomposition of urea into NH3
and CO2
(ii) Maltase (b) Conversion of glucose into ethyl
alcohol
(iii) Pepsin (c) Hydrolysis of maltose into glucose
(iv) Urease (d) Hydrolysis of cane sugar
(v) Zymase (e) Hydrolysis of proteins into
peptides

Match the vitamins given in Column I with the deficiency disease they cause
given in Column II.
Column I (Vitamins) Column II (Diseases)
(i) Vitamin A (a) Pernicious anaemia
(ii) Vitamin B1 (b) Increased blood clotting time
(iii) Vitamin B12 (c) Xerophthalmia
(iv) Vitamin C (d) Rickets
(v) Vitamin D (e) Muscular weakness
(vi) Vitamin E (f) Night blindness
(vii) Vitamin K (g) Beri Beri
(h) Bleeding gums
(i) Osteomalacia

Coagulation of egg white on boiling is an example of denaturation of protein.
Explain it in terms of structural changes.

Coagulation of egg white on boiling is an exa

How will you distinguish 1° and 2° hydroxyl groups present in glucose?
Explain with reactions.

Describe the term D- and L- configuration used for amino acids with examples.

How do enzymes help a substrate to be attacked by the reagent effectively?

Which monosaccharide units are present in starch, cellulose and glucose and
which linkages link these units?

What are glycosidic linkages? In which type of biomolecules are they present?

Which moieties of nucleosides are involved in the formation of phosphodiester
linkages present in dinucleotides? What does the word diester in the name of
linkage indicate? Which acid is involved in the formation of this linkage?

How do you explain the presence of an aldehydic group in a glucose molecule?

Activation energy for the acid catalysed hydrolysis of sucrose is 6.22 kJ mol–1,
while the activation energy is only 2.15 kJ mol–1 when hydrolysis is catalysed
by the enzyme sucrase. Explain.

Protein found in a biological system with a unique three-dimensional structure
and biological activity is called a native protein. When a protein in its native form,
is subjected to a physical change like change in temperature or a chemical change
like, change in pH, denaturation of protein takes place. Explain the cause.

Protein found in a biological system with a unique three-dimensional structure
and biological activity is called a native protein. When a protein in its native form,
is subjected to a physical change like change in temperature or a chemical change
like, change in pH, denaturation of protein takes place. Explain the cause.

Amino acids behave like salts rather than simple amines or carboxylic acids.
Explain.

Sucrose is dextrorotatory but the mixture obtained after hydrolysis is
laevorotatory. Explain.

Why must vitamin C be supplied regularly in diet?

How do you explain the presence of five —OH groups in glucose molecule?

During curdling of milk, what happens to sugar present in it?

Some enzymes are named after the reaction, where they are used. What name
is given to the class of enzymes which catalyse the oxidation of one substrate
with simultaneous reduction of another substrate.

α-Helix is a secondary structure of proteins formed by twisting of polypeptide
chain into right handed screw like structures. Which type of interactions are
responsible for making the α-helix structure stable?

Amino acids can be classified as α-, β-, γ-, δ- and so on depending upon the
relative position of amino group with respect to carboxyl group. Which type
of amino acids form polypetide chain in proteins?

Which sugar is called invert sugar? Why is it called so?

Aldopentoses named as ribose and 2-deoxyribose are found in nucleic acids.
What is their relative configuration?

Monosaccharides contain carbonyl group hence are classified, as aldose or
ketose. The number of carbon atoms present in the monosaccharide molecule
are also considered for classification. In which class of monosaccharide will
you place fructose?

Under what conditions glucose is converted to gluconic and saccharic acid?

Name the linkage connecting monosaccharide units in polysaccharides.

In nucleoside a base is attached at 1′ position of sugar moiety. Nucleotide is
formed by linking of phosphoric acid unit to the sugar unit of nucleoside. At
which position of sugar unit is the phosphoric acid linked in a nucleoside to
give a nucleotide?

How do you explain the presence of all the six carbon atoms in glucose in a
straight chain?

Name the sugar present in milk. How many monosaccharide units are present
in it? What are such oligosaccharides called?

What are the different types of RNA found in the cell?

Write the important structural and functional differences between DNA and RNA.

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

What is the difference between a nucleoside and a nucleotide?

What are nucleic acids? Mention their two important functions.

Why are vitamin A and vitamin C essential to us? Give their important sources.

How are vitamins classified? Name the vitamin responsible for thecoagulation of blood.

What is the effect of denaturation on the structure of proteins?

What are enzymes?

How do you explain the amphoteric behaviour of amino acids?

Differentiate between globular and fibrous proteins.

What type of bonding helps in stabilising the ∝-helix structure of proteins?

What are the common types of secondary structure of proteins?

Define the following as related to proteins

(i) Peptide linkage (ii) Primary structure (iii) Denaturation.

What are essential and non-essential amino acids? Give two examples ofeach type.

Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.

What happens when D-glucose is treated with the following reagents?

(i) HI (ii) Bromine water (iii) HNO₃

What is the basic structural difference between starch and cellulose?

What are the hydrolysis products of (i)sucrose and (ii)lactose?

What is glycogen? How is it different from starch?

What do you understand by the term glycosidic linkage?

Classify the following into monosaccharides and disaccharides.

Ribose, 2-deoxyribose, maltose, galactose, fructose and lactose

Write two main functions of carbohydrates in plants.

What are reducing sugars?

What are monosaccharides?

When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA?

What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?

Why cannot vitamin C be stored in our body?

Where does the water present in the egg go after boiling the egg?

The melting points and solubility in water of amino acids are generally higher than that of the corresponding halo acids. Explain.

How do you explain the absence of aldehyde group in the pentaacetate of D-glucose?

What are the expected products of hydrolysis of lactose?

Glucose or sucrose are soluble in water but cyclohexane or benzene (simple six membered ring compounds) are insoluble in water. Explain.