Cell Metabolism 2

Question 1

intermediates in the tca cycle

Answer 1

can - citrate
i - isocitrate
keep - a-keto glutarate
selling - succinyl CoA
substances - succinate
for - fumerate
money - malate
officer - oxaloacetate

(ox + A-CoA => citrate)

Question 2

net products of tca

Answer 2

2NADH + 1FADH2 + 1GTP + 2CO2

= 12ATP

Question 3

krebs enzymes

Answer 3

soluble
in mitochondrial matrix

Question 4

amino acid degradation (+ which 7 molecules formed)

Answer 4

amino group removed + carbon skeleton funnelled into glucose production/tca

pyruvate, A-CoA, acetoacetyl-CoA, akg, succinyl-CoA, fumerate, oxloacetate

Question 5

ketogenic vs glucogenic amino acid

Answer 5

ketogenic = degraded into acetyl CoA

glucogenic = undergoes glycogenesis = glucose

Question 6

transamination

Answer 6

group transfer
amine group from amino acid to keto acid = new pair

Question 7

purpose of glycerol-phosphate shuttle

Answer 7

shuttle NADH from cytosol into matrix in skeletal muscle + brain

Question 8

purpose of malate-aspartate shuttle

Answer 8

shuttle NADH from cytosol into matrix in kidney, liver, heart

Question 9

which tca mutations can lead to cancer + how

Answer 9

mutations in genes coding iso-citrate dehydrogenase, succinate dehydrogenase and fumerase

causes warburg effect: preferential generation of lactate from glucose even in low O2 (increased glycolysis + decreased tca)

Question 10

fa vs carb metabolism

Answer 10

fa = double caloric yield
brain cant use fa

Question 11

acyl coA synthesis

Answer 11

FA + ATP + HS-CoA ===> Acyl CoA + AMP + PPi

(acyl-CoA synthase)

Question 12

purpose of carnitine shuttle

Answer 12

transfer of acyl CoA from cytoplasm to mito matrix through translocase

Question 13

primary carnitine deficiency

Answer 13

autosomal recessive
mutation in SLC22A5 which encodes carnitine transporter = carnitine not up taken by cell

encephalopathy, muscle weakness, cardiomyopathy and hypoglycaemia in childhood

Question 14

beta oxidation

Answer 14

catabolic process by which fatty acid molecules are broken down in mitochondria (acyl CoA => acetyl CoA)

no: turns = (no: carbons/2) -1

Question 15

b-ox of palmitic acid

Answer 15

16C palmitic acid + 7FAD + 7NAD + 7H2O + 7CoA

= 8CoA + 7FADH2 + 7NADH

= 129 ATP

Question 16

when are ketone bodies formed

Answer 16

when no carb metabolism as acetyl CoA cant enter TCA without oxaloacetate

e.g during fasting

Question 17

name 3 ketone bodies

Answer 17

acetoacetate
acetone
D-3 hydroxybutyrate

Question 18

which enzymes are involved in ketone body production

Answer 18

3 ketothiolase
HMG CoA synthase
HMG CoA cleavage enzyme
D-3-hb dehydrogenase

Question 19

fatty acid biosynthesis

Answer 19

sequential decarboxylative condensation which elongates acyl-CoAs by 2C

Question 20

enzymes involved in FA biosynthesis

Answer 20

elongation: Acetyl-CoA carboxylase + FA synthase
reduction: ketoreductase
dehydration: dehydratase
reduction: enol reductase

Question 21

beta-ox vs biosynthesis

Answer 21

CoA vs ACP carrier
FAD/NAD+ vs NADPH reducing power
mito-matrix vs cytoplasm

Question 22

where does elongation occur for fatty acids longer than 16C

Answer 22

mitochondria + ER

Question 23

enzymes catalysing desaturation of FAs

Answer 23

fatty acyl-CoA desaturases
add double bonds

Question 24

which enzyme catalyses the initial step of beta oxidation

Answer 24

Acyl-CoA dehydrogenase

Question 25

acyl-CoA dehydrogenases

Answer 25

short chain = <6C
medium chain = 6 -12C
long chain = 13 - 21C
v.long chain = >22C

Question 26

MCADD

Answer 26

medium chain acyl CoA dehydrogenase deficiency
auto-recessive (caucasians)
screened via heel prick test

no fasting over 10-12 hours
iv glucose if necessary