Glycosaminoglycans are usually linked to proteins to form proteoglycans. Which of the following is NOT a proteoglycan?

• Hyaluronan

• Aggrecan

• Betaglycan

• Syndecan-1

Reaction products inhibit catalysis in enzymes by

• covalently binding to the enzyme

• altering the enzyme structure.

• occupying the active site

• form a complex with the substrate.

In proteins, hydrogen bonds form as follows: Donor (D)-H---Acceptor (A). Hydrogen bond is more favorable if the angle between D-H and A is

• <90°

• 180°

• >180°

• 120°

Information in DNA is in the form of sequence of 4 bases namely A, T, G and C. The proportion of G is the same as that of C, and that of A is the same as that of T. Which of the following strands of DNA will potentially have maximum diversity (i.e. maximum information content per base)?

• length 1000 bases with 10% G

• Length 2000 bases with 10% A.

• Length 2000 bases with 40% T.

• Length 1000 bases with 25% T.

A 1% (w/v) solution of a sugar polymer is digested by an enzyme (20μg, MW = 200,000). The rate of monomer sugar (MW = 400) liberated was determined to have a maximal initial velocity of 10 mg formed/ min. The turnover number (min^-1) will be

• 5 × 10⁴

• 2.5 × 10^-2

• 4.0 × 10^-6

• 2.5 × 10⁵

In an alpha helical polypeptide, the backbone hydrogen bonds are between

• NH of n and CO of n + 4 amino acids.

• CO of n and NH of n + 3 amino acids

• CO of n and NH of n + 4 amino acids

• NH of n and CO of n + 3 amino acids

Following are three single stranded DNA sequences that form secondary structures.

(a) A T T G A G C G A T C A A T

(b) A T T G A G C G A T A T C A A T

(c) A G G G A G C G A T C C C T

Based on their stability, which one is correct?

• (a) = (b) = (c)

• (c) > (a) > (b)

• (b) > (c) = (a)

• (b) > (c) > (a)

A protein has one tryptophan and one tyrosine in its sequence. Assume molar extinction coefficients at 280 nm of tryptophan and tyrosine as 3000 and 1500 M^-1cm^-1, respectively. What would be the molar concentration of that protein if its absorption at 280 nm is 0.90?

• 2 mM

• 0.4 mM

• 0.2 mM

• 0.02 mM

Sting of a bee causes pain, redness and swelling. Melittin is a major peptide in bee venom. Melittin is a membrane binding peptide that is involved in activating phospholipase in the membrane. The possible target phospholipase that is activated by melittin is

• Phospholipase C to generate inositol phosphates.

• Phospholipase A₂ to generate arachidonic acid.

• Phospholipase D to generate 1', 3'-inositol.

• Phospholipase A₁ to generate palmitic acid

The glycolysis and citric acid cycles are important pathways to generate energy in the cell. Given below are statements regarding the production of ATP.

A. Electrons released during the oxidative steps of glycolysis and citric acid cycle produce 10 molecules of NADH and 2 molecules of FADH₂ per molecule of glucose.

B. Electrons released during the oxidative steps of glycolysis and citric acid cycle produce 20 molecules of NADH and 4 molecules of FADH₂ per molecule of glucose.

The coenzyme produced are oxidized by electron transfer chain.

D. The conversion of ADP and P_i to ATP takes place in the intermembrane space of mitochondria.

Which one of the following combinations of above statements is correct?

• A and B

• B and C

• C and D

• A and C