TLS Online TPP Program

#Question id: 2618


The three genes (lacZ, lacY, and lacA) are transcribed as a single mRNA from the promoter, these genes are expressed at high levels only when

#SCPH01 Biochemistry
  1. Lactose is available

  2. Glucose, the preferred energy source is available

  3. Three regulatory proteins are involved.

  4. The Lac repressor is encoded by the lacI gene, which is located near the CAP Site.

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TLS Online TPP Program

#Question id: 634

#SCPH05 I Biotechnology

An enzyme has a Vmax of 50 micromol product formed (minute x mg protein)-1 and a Km of 10 microM for the substrate. When a reaction mixture contains the enzyme and 5 microM substrate, which of the following percentages of the maximum velocity will be closest to the initial reaction rate?

TLS Online TPP Program

#Question id: 635

#SCPH05 I Biotechnology

The enymatic rate constant (kcat/Km) of orotidine 5ʹ-phosphate decarboxylase is 6 x 107 M-1s-1 and the nonenzymatic rate constant (kn) is 3 x 10-16 s-1.  What is the value of the enzymeʹs catalytic proficiency?

TLS Online TPP Program

#Question id: 636

#SCPH05 I Biotechnology

DNA polymerase contains a lysine residue that is important for binding to DNA. Mutations were found that converted this lysine to either glutamate, glycine, valine, or arginine. Which mutations would be predicted to be the most and least harmful to the ability of the enzyme to bind DNA?

Most

Least

(A)

Valine

Aspartate

(B)

Glycine

Arginine

(C)

Arginine

Glycine

(D)

Glutamate

Arginine

TLS Online TPP Program

#Question id: 637

#SCPH05 I Biotechnology

Effect of temperature on enzymatic catalysis is analysed by the rate v of a chemical reaction varies with temperature according to the Arrhenius Equation which explains the sensitivity of enzyme reactions to temperature. A plot to determination of the activation energy Ea involves

TLS Online TPP Program

#Question id: 638

#SCPH05 I Biotechnology

Match the following class of enzymes with them

Enzyme

Class of enzyme

A. Hexokinase

1

B. Phosphoglucoisomerase

2

C. Glyceraldehyde 3-phosphate dehydrogenase

3

D. Phosphoglycerate mutase

4

E. Enolase

5

F. Aldolase

TLS Online TPP Program

#Question id: 639

#SCPH05 I Biotechnology

Match the coenzymes in column I enzymes to class of enzymes in column II

A. Phosphofructokinase

1. Redox reaction

B. Enolase

2. Phosphoryl shift

C. Phosphoglycerate mutase

3. Dehydration

D. Glyceraldehyde 3 Phosphate dehydrogenase

4. Phosphoryl transfer