Question

Which amino acid substitutions are most likely to affect structure/function of the protein?

Question 31 options:

	1) Lys --> Arg
	2) Leu --> Ile
	3) Arg --> Glu
	4) Ser --> Thr

Drug A acts by competing with substrate S of the target enzyme. Drug B acts by binding only to the ES complex to form ESB (inactive). If the levels of A and B are fixed, an increase in level S (check all that applied)

Question 35 options:

	1) will increase the degree of inhibition by drug A.
	2) will decrease the degree of inhibition by drug A.
	3) will increase the degree of inhibition by drug B.
	4) will decrease the degree of inhibition by drug B.

How many fragments will result from trypsin cleavage of the following peptide?
Asp-Leu-Gln-Arg-Ile-Ala-Met-Trp-Phe-Lys-Gln-Met-Asp-Arg

Question 37 options:

	1) 1
	2) 2
	3) 3
	4) 4.

Glucose phosphorylation can be catalyzed by glucokinase or hexokinase. Glucokinase has a Km value of 20.0 mM, whereas hexokinase has a Km value of 0.2 mM. Which of the following statement is true? (check all that applied)

Question 39 options:

	1) hexokinase acts on glucose at a lower concentration.
	2) hexokinase acts at about half-maximal velocity at glucose concentrations of 10-11 mM.
	3) hexokinase acts on glucose only at a higher levels of glucose.
	4) glucokinase acts on glucose only at a higher glucose concentration.
	5) glucokinase phosphorylates most of the glucose at low glucose levels.

Which of the following is true?

Question 40 options:

	1) Enzymes that obey Michaelis-Menten kinetics have a sigmodial plot of reaction rate vs. substrate concentration
	2) Allosteric enzymes have a hyperbolic plot of reaction rate vs. substrate concentration.
	3) Michaelis-Menten kinetics describe the reactions of allosteric enzymes.
	4) Allosteric enzymes are important in the regulation of metabolic pathways.

When designing primers for PCR, scientists often compare the primer sequence to database sequence. This is to ensure that the sequence

Question 46 options:

	1) has a maximum number of homologous sequences
	2) absents from the database
	3) aligns with several different sequences
	4) aligns with a single sequence

In an enzyme catalyzed reaction that obeys Michaelis-Menten kinetics, which pair of graphs would illustrate competitive inhibition?
  

Question 47 options:

	1) unable to determine from the infomation provided
	2) plots 1 &3
	3) plots 2 & 4
	4) plots 1 & 4
	5) plots 2 & 3

Facilitated diffusion of membrane transport (check all that applied)

Question 48 options:

	1) requires coupling to ATP hydrolysis.
	2) requires a carrier protein.
	3) is driven by a difference in solute concentration.
	4) is an endergonic process.
	5) requires that the solute be uncharged.

Answer 1

Question-31.

Arg-->Glu this conversion will affect the structure of the protein as Arginine is positively charged basic amino acid and glutamic acid is negatively charged acidic amino acid.

Question 35

Option-2

A is a competative inhibitior of the enzyme and B is the non-competitive inhibitor of the enzyme. Therefore increasing the substrate concentration will lower the inhibitory effects of inhibitor A.

Question-37.

Option 3.

Trypsin cleaves the peptide bond between the carboxy group of lysine or arginine and the amino group of the adjacent amino acid. Therefore the three fragments will be

Asp-Leu-Gln-Arg

Ile-Ala-Met-Trp-Phe-Lys

Gln-Met-Asp-Arg

Question 39.

Option 4.

Hexokinase has higher affinity for glucose than glucokinase. But hexokinase is negatively regulated by Glucose-6-phosphate. Therefore at high glucose levels when hexokinase activitiy is high it is quickly inhibited by G-6-P. But glucokinase has a high Km that is low affinity and is acts on Glucose only at high concentrations and it is also not inhibited by G-6-P.

Question 40.

Allosteric enzymes are important for the regulation of metabolic pathways. Allosteric enzymes have a different site other that its substrate binding site where substances know as allosteric effectors bind and control the enzyme action. Glucose-6- phosphate is the allosteric inhibitor of hexokinase. AMP and ADP are the allosteric activator of phosphofructokinase.

Question 46.

Option 4.

It is compared to confirm the sequence so that it only binds in the 3' region of the gene of interest that we want to amplify by PCR.

Question 48.

Option- 3

It is a passive transport through transmembrane integral proteins. It doesn't requires any ATP hydrolysis as the ∆G for this reaction is negative. And is driven by the concentration gradient.

Question 47 cannot be done as the graph is not rendered with the question.