BIOCHEM MIDTERM 2 QUIZ QUESTION/PROBLEM SETS

Question 1

The structure to the left is what stereoisomer of glucose?

Answer 1

Alpha , since the OH on the anomeric Carbon is “down” on the opposite side of the molecule as the CH2OH group

Question 2

Which of the below is present in the nucleotides of RNA?

Answer 2

The one on the right

Why?

D-ribose (RNA)

2-deoxyribose (DNA) (missing oxygen for carbon #2)

Question 3

What class of enzymes would you expect to catalyze the following reactions?

Answer 3

hydrolase

Question 4

What class of enzymes would you expect to catalyze the following reactions?

Answer 4

oxireductase

Question 5

What class of enzymes would you expect to catalyze the following reactions?

Answer 5

-transferase

Question 6

What class of enzymes would you expect to catalyze the following reactions?

And are these isomers?

Answer 6

-isomerase

Question 7

Alcohol dehydrogenase (ADH) catalyzes the following reaction. to which class of enzymes does ADH belong

Answer 7

-oxireductase

Question 8

Answer 8

-

Question 9

Question 10

Answer 10

Question 11

Which of the following are complementary bases that are found in DNA:

A) Adenine and Guanine

B) Adenine and Thymine

C) Adenine and Cytosine

D) Guanine and Thymine

E) Cytosine and Thymine

Answer 11

B

Question 12

The backbone of a nucleic acid molecule consists of:

A) Alternating sugar and phosphate groups linked by phosphate ester bonds

B) Alternating sugar and nitrogen base groups linked by amide bonds

C) Alternating nitrogen bases and phosphate groups linked by amide bonds

D) Sugar molecules bonded from the #3 carbon of one molecule to the #5 carbon of the other by a glycosidic bond

E) Complementary bases joined by hydrogen bonds.

Answer 12

A

Question 13

A carbohydrate may be defined as a molecule:

A) Composed of amino groups and carboxylic acid groups bonded to a carbon skeleton

B) Composed of carbon atoms bonded to water molecules

C) Composed mostly of hydrocarbons and soluble in non-polar solvents

D) That is an aldehyde or ketone and that has more than one hydroxyl group

E) Whose name ends in ase

Answer 13

D

Question 14

Unsaturated triacylglycerols (triglycerides) are usually ____________ because __________

A) Liquids; they have relatively short fatty acid chains

B) Liquids; the kinks in their fatty acid chains prevent their fitting together closely

C) Liquids; they contain impurities from their natural sources

D) Solid; they have relatively long fatty acid chains

E) Solid; their flexible fatty acid chains allow the molecules to fit together closely.

Answer 14

B

Question 15

Which of the following are true about the glucose transporter (GLUT):

A) It is an example of active transport

B) It is an integral membrane protein that transports glucose across the membrane

C) It moves glucose across a membrane, and the net movement of glucose is against the concentration gradient (from low to high concentration)

D) The number of GLUT molecules on the surface of a muscle cell is regulated by insulin. When insulin interacts with a receptor on the surface of the cell glucose uptake increases.

E) Both B and D are true

Answer 15

E

Question 16

What is the function of an enzyme?

A) Structure and support

B) Nutritional reserves

C) Biochemical catalysts

D) Communication between cells

E) Physical protection

Answer 16

C

Question 17

The function of glycoproteins and glycolipids in cell membranes is to

A) vary the fluidity of the membrane as needed
B) mediate interactions between the cell and outside agents C) provide channels for facilitated diffusion

D) provide channels for active transport
E) act as energy sources for active transport

Answer 17

B

Question 18

The function of a receptor on a cell membrane is to

A) Receive messages and store the information for later use.

B) Interact with a first message and hold the information until it can be passed on to

a second message

C) Cause a chemical change in the messenger to indicate that it has received the

information.

D) Receive messages that cause a series of changes within the cell resulting in a

biochemical response

E) Release chemicals which interact with other receptors

Answer 18

D

Question 19

All of the below statements are true about vitamins except:

A) It is possible to overdose on fat soluble vitamins because they accumulate in fatty

tissue

B) Fat-soluble vitamins have a high proportion of polar carbonyl and hydroxyl groups.

C) Itisdifficulttooverdoseonwater-solublevitaminsbecauseexcessamountscanbe excreted in the urine

D) VitaminA,D,E,Karefat-soluble

E) Vitamin C, B are water soluble

Answer 19

B

Question 20

When an enzyme is saturated

A) It has been completely consumed and the reaction cannot occur again until new enzyme is produced

B) The substrate concentration is low relative to the enzyme concentration and the rate is directly proportional to substrate concentration

C) The substrate concentration is high relative to the enzyme concentration and the rate is directly proportional to substrate concentration

D) The substrate concentration is high relative to the enzyme concentration and the reaction rate approaches its maximum

E) None of the above

Answer 20

D

Question 21

Glycogen stored in muscles is hydrolyzed to glucose by the enzyme glycogen

phosphorylase. What covalent modification activates this enzyme?

Answer 21

Phosphorylation

Question 22

Which statement concerning coenzymes and redox reactions is incorrect

A) Oxidation is a loss of electrons and can be considered as a loss of hydrogen or gain

of oxygen.

B) Reduction is a gain of electrons and can be considered as a gain of hydrogen or loss

of oxygen.

C) An oxidation reaction cannot occur unless a reduction reaction also occurs

D) NAD+ is the reduced form of NADH

E) Reduced Co-enzymes are products of carbohydrate, lipid and protein catabolism and

ultimately produce ATP

Answer 22

D

Question 24

When a molecule other than the correct substrate interacts with some part of the enzyme to alter the shape of the active site the process is called

A) Competitive inhibition

B) Noncompetitive inhibition

C) Irreversibleinhibition

D) Activation

E) Covalent modifications

Answer 24

B

Question 25

Note to add: There are more examples from all 3 problem sets that I did not include in this study set because Dr.Murphy either put the answer as “see lecture slides” or there wasnt a key.