KAZAK 1

Question 1

what is metabolism

Answer 1

the process through which living systems acquire and utilise the free energy they need to carry out their various functions

Question 2

how is ATP hydrolysis used as an energy source?

Answer 2

ATP is kept at high levels and ADP is kept low
disequilibrium
there is a driving force for hydrolysis
there is nothing inherently energetic in ATP

Question 3

what stores more energy than glucose does?

Answer 3

fatty acids store more energy than glucose

Question 4

what is anabolism

Answer 4

go from simple to complex molecules
requires energy
from ATP to ADP
endergonic

Question 5

what is catabolism?

Answer 5

go from complex to simple
exergonic
ADP Pi + ATP

Question 6

what are the three stages of metabolism?

Answer 6

stage 1: conversion of polymers and complex lipids with monomeric intermediates
stage 2: conversion of monomeric sugars, amino acids, and lipids with simpler organic compounds
stage 3: degradation or synthesis from inorganic compounds including CO2, H2O and NH3

Question 7

what are the two options that can happen to pyruvate?

Answer 7

can be oxidised to CO2+H2O in the mitochondria
can be made into lactate to keep glycolysis going

Question 8

what is the product of glycolysis for each glucose?

Answer 8

2 pyruvates
2 ATPs
2 NADH

Question 9

what is the function of NAD

Answer 9

electron acceptor
the reduced form is NADH
when you oxidise something you reduce NAD

Question 10

how is NADH recycled and converted back to NAD?

Answer 10

NADH is oxidised at the electron transport chain
the final electron acceptor is oxygen, to make water

Question 11

what is gluconeogenesis?

Answer 11

reverse of glycolysis
happens in the liver
maintain blood glucose levels

Question 12

what are futile cycles

Answer 12

if both pathways happened at the same time you would consume all the ATP you produce
but that doesn’t happen
more ATP would be consumed in the endergonic reactions of fatty acid synthesis than produced in the oxidation reactions
no useful work would be done

Question 13

how are futile cycles regulated?

Answer 13

allosteric regulation stops futile cycles
product of one pathway inhibits the other
covalent regulation (phosphorylation can stop the cycle)
compartmentalisation: keep two parts separate

Question 14

what is an example of a futile cycle?

Answer 14

fatty acid being converted to acetyl-CoA by ATP hydrolysis
acetyl CoA being converted to fatty acid by using ATP

Question 15

what does fermentation produce?

Answer 15

carbon dioxide and ethanol

Question 16

what is a pathway that favors glycolysis?

Answer 16

put phosphate on metabolites which have lower delta G than ATP and have a higher phosphorylation potential, therefore they can phosphorylate ADP

Question 17

what is substrate level phosphorylation

Answer 17

high energy substrate transfers phosphate to ADP

Question 18

what are tissues that synthesise glucose?

Answer 18

liver and kidney cortex

Question 19

what are tissues that use glucose as their primary energy source

Answer 19

brain and nervous system
muscle
kidney medulla
erythrocytes
testes

Question 20

how many steps of glycolysis are there and how can they be separated in two stages?

Answer 20

there are 10 steps
first 5 steps: energy investment, make high energy metabolites
last 5 steps: energy generation

Question 21

what is the net product of glycolysis

Answer 21

2 pyruvates
2 ATP
2 NADH

Question 22

what is an intermediate before pyruvate is made

Answer 22

triose phosphate

this card is stupid

Question 23

how many lactate molecules are made from one glucose?

Answer 23

2

Question 24

what is the reaction to turn pyruvate into lactate?

Answer 24

pyruvate+NADH+H –> L-lactate+NAD
this reaction is sponaneous

Question 25

what is the first step of glycolysis

Answer 25

glucose is phosphorylated by hexokinase, into G6P
first investment of ATP

Question 26

what does the phosphorylation of glucose do?

Answer 26

it traps the glucose inside the cell, it is now too big to diffuse out

Question 27

what are the affinities of hexokinase and glucokinase?

Answer 27

hexokinase: low Km, high affinity for glucose
glucokinase: hexokinase in the liver, low affinity for glucose, not as much need for trapping glucose inside

Question 28

what is the 3rd step of glycolysis?

Answer 28

fructose-6-phosphate is turned into fructose 1-6 bisphosphate by phosphofructokinase
second investment of ATP

Question 29

what are the 4th and 5th steps of glycolysis?

Answer 29

cleavage of FBP into triose DAHP and trios GAP by aldolase
isomerisation by triose phosphate isomerase

Question 30

what is step 6 of glycolysis?

Answer 30

GAP is oxidised and phosphorylated by GAPDH into BPG, and NADH is generated

Question 31

what is special about BPG

Answer 31

the first intermediate with a high phosphorylation transfer potential (even higher than ATP)
first step of the energy generation stage

Question 32

what is step 7 of glycolysis?

Answer 32

BPG is turned into 3PG by phosphoglycerate kinase, with the generation of ATP as a side product

Question 33

how are steps 6 and 7 of glycolysis thermodynamically coupled?

Answer 33

step 7 drives step 6 forwards
step 7 removes product from step 6-> pushes that reaction forward

Question 34

what is step 9 of glycolysis?

Answer 34

2PG is converted to PEP by enolase
this reaction has a very low delta G

Question 35

what is step 10 of glycolysis?

Answer 35

PEP (high energy intermediate) is converted to pyruvate by pyruvate kinase which removes the phosphate
ATP is a side product

Question 36

which are the enzymes that are subjected to the most allosteric control?

Answer 36

the enzymes that drive very highly exergonic reactions, which are irreversible
HK, PFK, PK

Question 37

what proportion of glucose energy is captured in ATP by glycolysis?

Answer 37

2-3%