BC141: MCQ

Question 1

Select 1 coenzyme involved in the transfer of electrons and acyl groups:
a) lipoate
b) pyridoxal phosphate (PLP)
c) tetrahydrofolate
d) coenzyme
e) thiamin pyrophosphate (TPP)

Answer 1

a) lipoate

it is the salt (conjugate base) of lipoic acid and is involved in oxidative metabolism and one-carbon metabolism where it acts as a “swinging arm” transferring acyl groups and electrons between different active sites.

Question 2

Which of the following is required by kinase?
a) molybdenum
b) iron
c) copper
d) zinc
e) mg-ATP complex

Answer 2

e) Mg-ATP complex

Question 3

T/F ribozymes catalyze protein synthesis

Answer 3

True

Question 4

Which statement is false regarding pyruvate dehydrogenase:
a) composed of multiple copies of 3 catalytic enzymes
b) converts pyruvate to oxaloacetate
c) has dihydrolipoamide dehydrogenase activity
d) has pyruvate dehydrogenase activity
e) has dihydrolipoamide acetyltransferase activity

Answer 4

b)

Question 5

T/F Catalases are a subclass of ligases.

Answer 5

False, they are a subclass of oxidoreductase enzymes, (class 1)

Question 6

T/F the fourth figure in enzyme nomenclature is the serial number of the enzyme in its subclass.

Answer 6

False. It is the enzyme in its sub-subclass.

Question 7

T/F the 2nd figure indicates the subclass while the 3rd figure gives the subclass.

Answer 7

True

Question 8

T/F proteases cleave peptide bonds

Answer 8

True

Question 9

T/F Hydratase remove a water to render a double bond.

Answer 9

False, hydratase add a water to a double bond.

Question 10

T/F racemase move groups within a molecule.

Answer 10

True

Question 11

T/F Phosphates add a phosphate to a substrate.

Answer 11

False, phosphatases remove a phosphate from a substrate.

Question 12

What is the optimum pH of most enzymes? (in endo-enzymes as opposed to exo-enzymes)

Answer 12

7.4

Question 13

Lysozymes prevent bacterial growth by acting as…

Answer 13

a glycosidase

Question 14

What is Michalis Constant?

Answer 14

Km is the concentration of substrate when the rate of reaction proceeds at half of the maximum velocity.

Question 15

What are characteristics of fat soluble vitamins?

Answer 15

• isoprene units
• stored for a long time
• need lipoproteins
• need bile acids/salts

Question 16

Can fat-soluble vitamins synthesize fatty acids?

Answer 16

No they cannot.

Question 17

Vitamin A has…
a) 1 vitamer
b) oxidation-reduction function
c) a chromatin ring
d) they form carotenes
e) a role in growth

Answer 17

e) a role in growth.

Vitamin A does not form carotenes, and has 3 vitamers, the retinoids.

Question 18

What does insulin secretion require?
a) retinal
b) 1-24 DHCC
c) 1-25 DHCC
d) tetra hydroxyl cholecalciferol
e) tocotrienols

Answer 18

c) 1-25 CHCC
the activated form of vit. D

Question 19

How is vitamin A deficiency treated?
a) injection of retinol palmitate
b) orally ingested palmitate
c) injection of retinol-binding protein
d) intravenous injection of retinol palmitate

Answer 19

a) injection of retinol palmitate (intramuscular, not intravenous)

Question 20

hydroxyproline is formed by and is a component of…

Answer 20

• ascorbic acid
• osteocalcin, connective tissue, and collagen.

Question 21

status of vitamin D is estimated by…

Answer 21

1-25 DHCC

Question 22

How can vitamin C decrease allergic respone?

Answer 22

By cleaving histamine

Question 23

Precursor of second messengers:

Answer 23

Phosphatidylinositol

Question 24

Epilepsy drugs may lead to…
a) toxicity of retinoic acid
b) toxicity of vit E
c) toxicity of vit D
d) deficiency of vit D
e) deficiency of vit E

Answer 24

d) deficiency of vit D

Question 25

Where is the chroman ring found?

Answer 25

In tocopherol

Question 26

osteocalcin synthesis needs...

Answer 26

carboxylation by phylloquinon

Question 27

Where is vit A2 found in?

Answer 27

freshwater fish

Question 28

endogenous vitamin synthesis is... a) biotin b) K2 c) retinal d) carotenes e) tocotiens

Answer 28

c) retinal the carotene to retinal pathway is totally endogenous synthesis.

Question 29

The accumulation of cholecalciferol may occur due to...

Answer 29

an increase in body fat.

Question 30

What is vit. K a cofactor for?

Answer 30

gamma carboxylation of glutamic acid

Question 31

The pellagra preventive factor is: a) riboflavin b) ascorbate c) pantothenic acid d) niacin e) pyridoxine

Answer 31

d) niacin

Question 32

A deficiency in thiamin will increase the concentration of...

Answer 32

pyruvic acid and lactic acid in blood

Question 33

riboflavin deficiency pathology:

Answer 33

cheilosis

Question 34

precursor of CoA

Answer 34

pantothenate (B5)

Question 35

Where is cholecalciferol hydroxylated to form 25-hydroxy calcidiol?

Answer 35

In the liver

Question 36

What oxidatively cleaves beta carotene?

Answer 36

dioxygenase

Question 37

The most important natural antioxidant;

Answer 37

vitamin E!! :)))

Question 38

vitamin needed for hydroxyproline formation in collagen:

Answer 38

vit. C

Question 39

hypervitaminosis K in neonates may cause... a) porphyria b) ataxia c) jaundice d) pellagra e) aspartate

Answer 39

c) jaundice

Question 40

Which amino acid is used to synthesize niacin in the body?

Answer 40

tryptophan

Question 41

What can be used to treat Wernicke-Korsakoff syndrome and beriberi?

Answer 41

vit. B1: thiamin

Question 42

biotin is a coenzyme for the enzyme:

Answer 42

carboxylase

Question 43

B12 deficiency can be diagnosed by urinary excretion of...

Answer 43

methylmalonate

Question 44

Deficiency caused by raw eggs:

Answer 44

biotin

Question 45

hydrogen-transferring coenzyme:

Answer 45

B2, B3 FAD, NAD+

Question 46

Allosteric enzymes regulate the formation of products through... a) feedback inhibition b) non-competitive inhibition c) competitive inhibition d) only a & b e) all of these

Answer 46

Non-competitive inhibition