TLS Online TPP Program

#Question id: 11131


Which statement concerning the generation of an action potential is correct?

#Unit 7. System Physiology – Animal
  1. When the membrane potential in the soma/axon hillock dips below “threshold,” an action potential is initiated
  2. The action potential is initiated in synaptic boutons
  3. The least number of voltage-gated sodium channels in an axon is found near the node of Ranvier
  4. Once an action potential is initiated, it will always run its course to completion
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TLS Online TPP Program

#Question id: 638

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the following class of enzymes with them

EnzymeClass of enzyme
A. Hexokinase1
B. Phosphoglucoisomerase2
C. Glyceraldehyde 3-phosphate dehydrogenase3
D. Phosphoglycerate mutase4
E. Enolase5
F. Aldolase

TLS Online TPP Program

#Question id: 637

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 636

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 635

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 634

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 633

#Unit 1. Molecules and their Interaction Relevant to Biology

An amino acid transporter protein is responsible for the transport of a specific amino acid across a membrane. The KI values of several competitive inhibitors of the amino acid transporter are shown above. Based on these data, which of the following is most likely the amino acid transported by this protein?