Biochemistry : Identifying Specific Protein Functions

Study concepts, example questions & explanations for Biochemistry

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Example Questions

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Example Question #171 : Identifying Biochemical Molecules

Kinase reactions involve enzymes that __________.

Possible Answers:

use  as an oxidizing agent

reduce aldehydes to alcohols

add phosphate groups to another molecule

transfer groups from one part of a molecule to another part

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 #12 : Identification By Function

What is the action of a phosphatase?

Possible Answers:

Removes of a phosphate group

Adds of a phosphate group

Breaks a chemical bond

Rearranges bonds in a molecule

Forms a chemical bond

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 #173 : Identifying Biochemical Molecules

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

Possible Answers:

Charges within the channel repel all other molecules

The channel uses internal enzyme activity to degrade all other molecules

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

The channel constricts down to  from an initial 

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

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 #174 : Identifying Biochemical Molecules

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

Possible Answers:

Vitamin K

Vitamin B12

Vitamin E

Vitamin A

Vitamin D

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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