Question

C4. Amino Acids and Proteins Amino acids are organic compounds that contain amine and carboxyl functional groups, along with a side chain specific to each amino acid. Clearly and concisely explain the process of dipeptide formation. [10 Marks) C5. Nucleic Acids Humans have two types of nucleic acids in their bodies: DNA and RNA. These molecules contain the set of instructions for our cells: they determine who and what we are. Compare and contrast DNA and RNA. [10 Marks] C6. Enzymes a) What do you understand by the term enzyme? [1 Mark] b) Define the term Energy of Activation. [1 Mark] c) What type of proteins are enzymes? [1 Mark] d) What are enzyme co-factors? [1 Mark] e) What is an enzyme without a co-factor called? [1 Mark] f) Explain how an enzyme controlled reaction is affected by changes in potential hydrogen. [3 Marks] g) Explain how a non-competitive enzyme inhibitor affects enzyme activity. [2 Marks] C7. Vitamins and Minerals Vitamins and minerals are required by the body for optimal health. List 5 fat soluble vitamins and for each mention the disease caused by its deficiency. [10 Marks]

Answer 1

ANSWER

C.4-

• A dipeptide is formed by joining of 2 amino acid with Peptide bond. by the chemical reaction viz. Condensation Reaction
• .The bond between the two amino acids forms between the carboxyl group  and the amino group.by producing water as biproduct.

C.5-

DNA	RNA
DNA has deoxyribose sugar	RNA has ribose sugar
it has double helical structure	it is single stranted
it is less reactive due to presence of C-H BOND	it has larger grooves, so they are highly reactive
It contain nitrogen base ADENINE,GUANINE,THYMINE AND CYTOSINE	it contain nitrogen base ADENINE, GUANINE , CYTOSINE ,URACIL

C.6-

a) Enzymes are biological molecules that are important for life.enzymes used as catalyst in a reaction.

b) The term energy of activation , in general, refers to the minimum amount of energy required to activate atoms or molecules to a condition in which they can undergo a chemical reaction or physical transport. When an enzyme binds to its substrate it lowers the activation energy of the reaction so that the reaction completes more quickly.

c)Enzymes are basically globular proteins . These globular proteins are amazing active catalysts.

d) A cofactor is basically a non protein chemical component that are considered as 'helper molecules.Enzymes require cofactors for its proper functioning of biological activity.

e) An inactive enzyme without the cofactor is called apoenzyme.

f) Proteins are sensitive to their environment. Hydrogen ions are positively charged particles that interact with negatively charged particles of protein macromolecules.These interactions disrupt the delicate balance of forces which hold the protein in its appropriate 3D shape.Once this alters the shape of the enzyme it eventually affects the active site and change the ability to interact with substrate.

g)

• A non-competitive enzyme inhibitor doesnt block the substrate binding.site (Allosteric site)
• Allosteric enzymes display a sigmoidal curve
• This is type of inhibition is reversible.and decreases the turnover rate of an enzyme rather than interfering with the amount of substrate.therefore the reaction is slowed rather than being stopped and also cannot be increased by increasing substrate.

C.7)

• The fat soluble vitamins A,D,E and K are absorbed in the intestine in the presence of fat. They are abundant in high-fat foods.
• Vitamin A is not a single compound rather is a group of fat soluble compounds called retinoids.
• The most common dietary form of vitamin A is retinol. It is abundant in green leafy vegeatables.
  It plays a vital role in maintaining vision.
• Deficiency of vitamin A leads to night blindness. It also impairs immune functions.
  It may also prevent growth in children.
• Since vitamin A is vital for hair growth its deficiency may lead alopecia or hair loss.
  Vitamin D or sunshine vitamin is produced in oir skin when exposed to sunlight.