Cell Metabolism 1

Question 1

6 metabolic reactions

Answer 1

redox
ligation requiring ATP cleavage
isomerisation
group transfer
hydrolytic
addition/removal of functional groups

Question 2

ligation requiring ATP cleavage

Answer 2

covalent bond formation

Question 3

hydrolytic

Answer 3

bond cleavage using water

Question 4

add FG

Answer 4

double bond ==> single

Question 5

properties of glycolysis

Answer 5

anaerobic
cytosolic

Question 6

glycolysis general principle

Answer 6

6C glucose ==> 2x3C pyruvate

formation of 2 high energy compounds using ATP + splitting of compounds, releasing energy to form ATP

Question 7

glycolysis enzymes in order

Answer 7

hexo-kinase
phosphoglucose-isomerase
phosphofructo-kinase
aldolase
triose phosphate isomerase

GA3P dehydrogenase
phosphoglycerate-kinase
phosphoglycerate-mutase
enolase
pyruvate-kinase

Question 8

which step of glycolysis is NADH made from NAD+ & H+

Answer 8

step 6: dehydrogenation of GA3P into 1,3-biphosphoglycerate

Question 9

glycolysis net gain

Answer 9

2ATP + 2NADH = 8ATP

Question 10

significance of first stage

Answer 10

irreversible
commits cell to subsequent reactions
traps glucose in cell by negative charge

Question 11

why is fructose made in step 2

Answer 11

can be broken down into equal halves when cleaved (GA3P + DHAP)

Question 12

how to regulate entry of sugars into the pathway

Answer 12

regulate phosphofructokinase

Question 13

whats the only fatal enzymopathy

Answer 13

TPI deficiency
avg lifespan = 6 years

affects RBC + brain most as rely on glucose for energy rather than other substrates

Question 14

alcohol fermentation reactions

Answer 14

pyruvate ==> acetaldehyde
(H+ ==> CO2)

acetaldehyde ==> ethanol
(NADH + H+ ==> NAD+)

Question 15

alcohol fermentation enzymes

Answer 15

pyruvate carboxylase + alcohol dehydrogenase

Question 16

lactate generation

Answer 16

pyruvate ==> lactate
(H+ + NADH ==> NAD+)

lactate dehydrogenase

Question 17

why NAD+ regenerated in anaerobic

Answer 17

when O2 = limited, ATP can still be made by glycolysis
NAD+ needed for 6th stage (dehydrogenation of GA3P)

Question 18

acetyl CoA generation

Answer 18

pyruvate + HS-CoA ==> ACoA + CO2
(NAD+ ==> NADH)

pyruvate dehydrogenase complex

Question 19

thioester bond

Answer 19

high energy linkage so easily hydrolysed
allows ACoA to readily donate 2C acetate

Question 20

Beri Beri disease

Answer 20

thiamine deficiency (vitamin B1)
thiamine = PDH cofactor (loses proton and remaining carbanion attacks pyruvate)

damage to PNS, muscle weakness + decreased cardiac output

Question 21

why is glucose trapped after phosphorylation in the first step

Answer 21

G6P cannot cross the lipid bilayer as it has a negative charge

glucose concentration in cell is decreased - low concentration grad