Chap 14

Question 0

Phosphoester bond

Answer 0

P group and adenosine

Question 1

Adenosine

Answer 1

In atp, adenine + ribose

Question 2

Phosphoanhidride bond

Answer 2

P and p group bond;

Question 3

Why is atp catabolism so exergonic?

Answer 3

3 p tail doesn’t have res stabil; electrostatic repul of 3p tail; 3p tail less solvation energy; depends also on ph and ionic strength. However its catabolism is thermo favored but kinetically disfavored

Question 4

How do coupled rxns get high G rxns to complete spontaneously? thermodynamically

Answer 4

2nd( more exergonic) rxn uses up the products from 1st (endergonic) rxn, shifting the equilibrium and making the 1st rxn make more products

Question 5

How does hexokinase work?

Answer 5

Lowers the high activation energy of p group transfer from atp to glucose.

Question 6

What does inorganic pyrophosphatase do? When is it used?

Answer 6

Hydrolyzes product of pyrophosphate cleavage= PPi; attachment of amino acids to tRNA for protein synth

Question 7

Substrate lv phospho’tion? What enzymes do it?

Answer 7

Regen’tion of atp by coupling to a more exergonic process. High energy compound gives its P group to adp; kinases

Question 8

What do phosphoguanidines and acyl phosphates have in common?

Answer 8

Greater phosphoryl group transfer potential than atp- transfers p group to adp; g6p has low gt potential so cant make atp

Question 9

Orthophosphate cleavage

Answer 9

Cleaves phosphoanhydride bond

Question 10

Pyrophosphate cleavage

Answer 10

When 2 p groups are cleaved off together as group

Question 11

Roles of enzymes in metabolic pathways? 3

Answer 11

Speed up rxns so they can support life; specificity- efficient, prevents buildup of useless/toxic byproducts; coupling- endergonic w exergonic

Question 12

4 main types of rxns

Answer 12

Oxidations reductions- oxidireductases; group transfer rxns- transferase and hydrolases; elimination isomerization and rearrangements-isomerases and mutases; make/break C bonds- hydrolases, lyases, ligases

Question 13

Explain fx of phosphagens/phosphocreatine

Answer 13

Gen of phoscreatine is near equilibrium, makes it when atp is high and catabolizes it when atp low; atp buffer

Question 14

Nucleoside triphosphates; nucleoside diphosphate kinase; adenylate kinase

Answer 14

Protein and nuke acid synth; makes ntp from atp and ndp; amp+atp=2adp no water in active site so phospho group transfer occurs, not hydrolysis

Question 15

Thioester

Answer 15

Candidate for primitive high energy compound; ind of oxidative phosphorylation. Bond in rxn intermediate Cys, and in acetyl-CoA

Question 16

Coenzyme A

Answer 16

B-mercaptoethanolamine group amide linked to panthotenic acid which is attached to a 3’phosphoadenosine moiety via pyrophosphate bridge; carrier of acetyl and acyl groups

Question 17

Why are thioesters high energy?

Answer 17

S has large atomic radius so it has less resonance stabilization.

Question 18

Diff btw vitamin and coenzyme?

Answer 18

Vits are precursor for coenzymes