Lesson 8 - metabolism and vitamins

Question 1

what are recurring energy carrying molecule motifs

Answer 1

primarily ATP

Question 2

what are recurring electron carrier motifs

Answer 2

NAD(P), NAD(P)H + H, FAD, FMN, FADH2, FMNH2

Question 3

what is a recurring “2 C” carrier motif

Answer 3

acetyl CoA

Question 4

what are two subdivisions of cofactors

Answer 4

essential ions and coenzymes

Question 5

what are two subdivisions of essential ions

Answer 5

activator ions (loosely bound) and metal ions of metalloenzymes (tightly bound)

Question 6

what are two subdivisions of coenzymes

Answer 6

cosubstrates (loosely bound) and prosthetic groups (tightly bound)

Question 7

what is the reaction for NAD to NADH

Answer 7

NAD + 2 H+ + 2 e+ —-> NADH + H+

Question 8

where is the reactive site for NAD+

Answer 8

on the carbon directly across from the N+ in the ring structure

Question 9

where is the reactive site for NADP+

Answer 9

the same place as NAD+

Question 10

what is the reactions for NAD+ to NADH

Answer 10

two R groups lead to a CHOH. you add NAD+ and it takes the two hydrogens leaving a carboxyl group and NADH + H+

Question 11

where are the reactive sites on FAD

Answer 11

the top middle N and the bottom right N

Question 12

what is the reaction for FAD to FADH2

Answer 12

FAD takes two hydrogen and two electrons and attaches them to its two reactive sites to make its reduced form FADH2

Question 13

describe how oxygen esters are stabilized

Answer 13

they’re stabilized by resonance structures not available to thioesters

Question 14

what is vitamin precursor for NADH and NADPH

Answer 14

nicotinate (niacin)

Question 15

what is vitamin precursor for FADH2

Answer 15

riboflavin (vitamin B2)

Question 16

what is vitamin precursor for FMNH2

Answer 16

riboflavin (vitamin B2)

Question 17

what is vitamin precursor for coenzyme A

Answer 17

pantothenate

Question 18

what is vitamin precursor for thiamine pyrophosphate

Answer 18

thiamine (vitamin B1)

Question 19

what type of reaction is thiamine (B1) involved in

Answer 19

aldehyde transfer

Question 20

what type of reaction is riboflavin (B2) involved in

Answer 20

redox reaction

Question 21

what type of reaction is nicotinic acid (niacin) involved in

Answer 21

redox reaction

Question 22

what type of reaction is pantothenic acid involved in

Answer 22

acyl-group transfer

Question 23

compare B vitamins to other vitamins

Answer 23

B vitamins function as coenzymes. vitamins A, C, D, E, and K play a variety of roles, but do not serve as coenzymes

Question 24

name 3 regulators of enzyme activity

Answer 24

allostery (inhibitors or activators), covalent modification (phosphorylation), and control of gene expression (steroid hormone in mammals; operons in bacteria)

Question 25

name the first general property of allosteric enzymes

Answer 25

activity of allosteric enzymes are changed by inhibitors and activators (modulators) which bind to an enzyme and alter its geometry in the active site

Question 26

name second general property of allosteric enzymes

Answer 26

they possess quaternary structure

Question 27

name third general property of allosteric enzymes

Answer 27

there is a rapid transition between the active (R) and inactive (T) conformations

Question 28

name fourth general property of allosteric enzymes

Answer 28

the R form will be more active (lowering the apparent Km) while the T form will be less active (higher apparent Km)

Question 29

describe control of gene expression in allosteric enzymes

Answer 29

binding of specific molecules to promotor regions in DNA increases/decreases gene expression. For example, steroid hormones in mammals bind to a receptor which translocates to the nucleus. In bacteria operons are controlled by specific molecules (for example, amino acids, lactose, etc.)

Question 30

what is the difference between FMN/FAD and NAD(P)+

Answer 30

the oxidized or reduced forms of FMN and FAD are always prosthetic groups while the oxidized and reduced forms of NAD(P)+ are always soluble cosubstrates