Biochemistry : Identifying Specific Protein Functions

Study concepts, example questions & explanations for Biochemistry

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Example Question #11 : Identifying Specific Protein Functions

Kinase reactions involve enzymes that __________.

Possible Answers:

transfer groups from one part of a molecule to another part

add phosphate groups to another molecule

use  as an oxidizing agent

reduce aldehydes to alcohols

Correct answer:

add phosphate groups to another molecule

Explanation:

Kinases are enzymes that add phosphate groups to molecules. Phosphatases remove phosphate groups from molecules. Common reducing agents in biological systems are , and antioxidant molecules such as vitamins C and E. Transferases catalyze reactions in which one part of a molecule is transferred elsewhere on that same molecule or onto another molecule.

Example Question #11 : Identifying Specific Protein Functions

What is the action of a phosphatase?

Possible Answers:

Removes of a phosphate group

Forms a chemical bond

Breaks a chemical bond

Rearranges bonds in a molecule

Adds of a phosphate group

Correct answer:

Removes of a phosphate group

Explanation:

The action of a phosphatase is to remove a phosphate group from a molecule. A kinase adds phosphate groups, an isomerase rearranges bonds, a ligase forms a chemical bond, and a lyase breaks a chemical bond.

Example Question #12 : Identifying Specific Protein Functions

What is one of the ways by which a potassium channel maintains great specificity for  ions?

Possible Answers:

The channel constricts down to  from an initial 

The channel uses internal enzyme activity to degrade all other molecules

The channel is always closed and only open when a  ion is present

The channel allows other molecules through, but then immediately sends them backwards through the channel 

Charges within the channel repel all other molecules

Correct answer:

The channel constricts down to  from an initial 

Explanation:

The potassium channel is initially  wide at its entry point - this already excludes many molecules that are not . As molecules travel further down the channel, though, the channel becomes much tighter and essentially only allows for  to continue. However,  is surrounded by water molecules. sheds these water molecules caged around it in order to move through the channel, thereby maintaining specificity for potassium and excluding water from the channel.

Example Question #12 : Identifying Specific Protein Functions

A deficiency in which fat soluble vitamin results in impaired night time vision?

Possible Answers:

Vitamin D

Vitamin B12

Vitamin K

Vitamin E

Vitamin A

Correct answer:

Vitamin A

Explanation:

Vitamins D, E, A, and K are all fat soluble vitamins. Vitamin A (retinol) plays an important role in the visual pigments within the rods and cones of the retina. Deficiency of this vitamin produces night blindness, as these important retinal cells are unable to function properly.

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