All Biochemistry Resources
Example Questions
Example Question #11 : Identifying Specific Protein Functions
Kinase reactions involve enzymes that __________.
use as an oxidizing agent
add phosphate groups to another molecule
reduce aldehydes to alcohols
transfer groups from one part of a molecule to another part
add phosphate groups to another molecule
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 : Identifying Specific Protein Functions
What is the action of a phosphatase?
Forms a chemical bond
Removes of a phosphate group
Rearranges bonds in a molecule
Breaks a chemical bond
Adds of a phosphate group
Removes of a phosphate group
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 #11 : Identifying Specific Protein Functions
What is one of the ways by which a potassium channel maintains great specificity for ions?
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
Charges within the channel repel all other molecules
The channel is always closed and only open when a ion is present
The channel constricts down to from an initial
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 #13 : Identifying Specific Protein Functions
A deficiency in which fat soluble vitamin results in impaired night time vision?
Vitamin B12
Vitamin D
Vitamin A
Vitamin K
Vitamin E
Vitamin A
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.