new stuff for exam 3

Question 1

Ribonucleotide reductase

Answer 1

2 control sites: activity site (turns on or off) and specificity site (controls which substrate binds)

Question 2

when is ribonucleotide reductase turned on

Answer 2

high ATP

ATP binds to activity site to turn ON

Question 3

what happens when dATP concentration rises?

Answer 3

dATP displaces ATP at activity site and turns enzyme OFF

Question 4

dNDP to dNTP

Answer 4

ATP + dNTP to ADP + dNTP

E: nucleoside diphosphate kinase

Question 5

synthesizing thymine

Answer 5

dUMP to dTMP

E: thymidylate synthase

Question 6

regulation of dNTP synthesis occurs when

Answer 6

right before and during S phase of cell cycle

Question 7

regulation of dNTP synthesis

Answer 7

1) increases general purine and pyrimidine synthesis by increasing levels of synthetic enzymes
2) express ribonucleotide reductase
3) express thymidylate synthase
4) express TMP kinase

Question 8

Thymidylate synthase

Answer 8

dUMP is substrate

1 carbon carrier is 5,10 methylene THF

Question 9

what is leftover after nucleotides are deaminated?

Answer 9

ribose

Question 10

nucleotide salvage

Answer 10

we can add bases back to ribose

PRPP + hypoxanthine to IMP

Question 11

purine degradation

Answer 11

AMP or IMP to hypoxanthine

creates uric acid which must be excreted

Question 12

pyrimidine degradation

Answer 12

open rings

products are small molecules that are water soluble and can be degraded

Question 13

glutamine analogs

Answer 13

inhibit glutamate, inhibit lots of enzymes

sometimes a cancer treatment

Question 14

build up of dATP leads to

Answer 14

inability to make sufficient deoxyribonucleotides for DNA replication

Question 15

where is cholesterol stored in the liver?

Answer 15

lipid droplets

stored by ACAT

Question 16

well-fed state hormones

Answer 16

insulin: reports on blood glucose
leptin: senses stored energy as fat

Question 17

leptin

Answer 17

senses stored energy as fat in adipocytes

Question 18

leptin and gene expression

Answer 18

JAK kinases phosphorylate STATS which dimerize and move to nucleus to alter gene transcription

Question 19

sirtuin

Answer 19

a deacetylase that targets histones

responds to energy change

Question 20

if there isn’t enough energy around to make cholesterol,

Answer 20

AMPK phosphorylates HMG-CoA reductase to turn OFF the pathway

Question 21

AMPK functions

Answer 21

senses AMP and ATP binding
AMP activates AMPK
ATP inhibits AMPK