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Metabolism > session 3-pentose phosphate,TCA,electron transport,substrate/oxidative phosp,fatty acids,ketones > Flashcards

session 3-pentose phosphate,TCA,electron transport,substrate/oxidative phosp,fatty acids,ketones Flashcards

1
Q

what are the 2 major functions of the pentose phosphate pathway?

A
  • produce NADPH in cytoplasm (reducing power for lipid synthesis, maintain free -sh groups on cysteine to prevent formation of disulfide bridges)
  • produce 5 carbon sugar for nucleotide synthesis
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2
Q

where is the pp pathway highly active?

A

in dividing tissues

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3
Q

does the pentose phosphate pathway produce ATP and CO2, just CO2 or just ATP?

A

Co2 and is OXIDATIVE

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4
Q

in phase one of the pentose phosphate pathway, what is oxidised and decarboxylated?

A

glucose -6-phosphate (2nd in glycolysis pathway)

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5
Q

what enzymes are involved in phase 1 of the PP pathway?

A

glucose 6 phosphate dehydrogenase and 6-phosphogluconate dehydrogenase

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6
Q

what precursor does phase one of the PP pathway require?

A

NADP+

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7
Q

which parts of the body is the pentose phosphate pathway important in?

A

liver, adipose tissue and red blood cells

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8
Q

what is the overall equation for phase 1 of the pentose phosphate pathway?

A

glucose 6 phosphate + 2NADP+ —> C5 sugar phosphate + 2NADPH + 2H+ + 2CO2

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9
Q

what is the point of phase 2 of pp pathway?

A

converts any unused c5 sugar phosphates to glycolysis intermediates (e.g. fructose 6 phosphate)

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10
Q

why do RBCs require reducing power from NADPH?

A

prevent disulphide bridges forming and thus prevents heinz body formation

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11
Q

what are heinz bodies and what do they cause?

A
  • insoluble aggregates of denatured HB

- cause premature haemolysis

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12
Q

what is the role of PDH (pyruvate dehydrogenase)?

A

convert pyruvate into acetyl coA

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13
Q

Is the PDH reaction reversible or irreversible?

A

irreversible (as co2 is removed)

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14
Q

what is the main point of the TCA cycle?

A
  • catabolism of sugars, fatty acids,ketone bodies and alcohol
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15
Q

where does the TCA cycle occur?

A

mitochondrial MATRIX

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16
Q

what 3 molecules are required in the TCA cycle?

A

NAD+, FAD and oxaloacetate

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17
Q

does the TCA cycle function in the absence of oxygen?

A

NO

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18
Q

how many ATP molecules are produced per molecule of glucose?

A

32

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19
Q

list 3 of the anabolic functions of the TCA cycle

A

synthesis

  • non essential amino acids
  • haem and glucose
  • fatty acids
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20
Q

how much NADH, FADH2 and GTP is produced after two TCA cycles=one glucose?

A

6 NADH
2 FADH2
2 GTP

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21
Q

an irreversible step is allosterically inhibited by what in the TCA cycle?

A

NADH

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22
Q

Irreversible step in TCA cycle is activated by what?

A

ADP

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23
Q

irreversible step in TCA cycle is catalysed by what?

A

isocitrate dehydrogenase

24
Q

where does oxidative phosphorylation occur in mitochondria?

A

inner mitochondrial membrane

25
Q

how is atp synthesised in OP?

A

-electrons in FADH and NADH are transported across carrier molecules releasing energy to make ATP from ADP + Pi

26
Q

PMF: How else is the free energy from electrons used?

A

move protons from the inside of the inner mitochondrial (matrix side) membrane to the outside (inter membrane space side)
…produces electrochemical gradient (PMF)
-When H+ tried to move back in, this drives the synthesis of ATP

27
Q

2 moles of NADH gives how many moles of ATP?

A

5

28
Q

2 moles of FADH2 gives how many moles of ATP?

A

3

29
Q

DNP (dinitrophenol)/dinitrocresol/fatty acids increases permeability of membrane. What effect does this have?

A

H+ ions can move back in, without passing through ATP synthase complex….PMF dissipates as HEAT (contributes to BMR)
No phosphorylation of ADP
No inhibition of electron transport

30
Q

what does UCP1 (uncoupling protein) do? (aka..thermogenin)

A
  • in brown adipose tissue
  • enables mammals to survive the cold as it is involved in thermogenesis
  • allows H+ to move back into matrix without passing through ATP synthase so energy is lost as HEAT
31
Q

what is released from the sympathetic nervous system to release heat?

A

noradrenaline

32
Q

list the four features of oxidative phosphorylation

A
  • requires membranous complexes
  • energy coupling through PMF
  • cannot occur in absence of oxygen
  • major process for ATP synthesis
33
Q

list 4 features of substrate level phosphorylation

A
  • requires soluble enzymes
  • energy coupling occurs directly through formation of a high energy of hydrolysis bond
  • can occur without oxygen to a limited extent
  • minor process for ATP synthesis
34
Q

what does it mean if lipids are more reduced than carbohydrates?

A
  • less oxygen

- more hydrogens per carbon atom

35
Q

what hydrolyses triacylglycerol, what enzyme is used and what is released?

A
  • small intestine
  • pancreatic lipase
  • glycerol and fatty acids (fuel molecules) produced
36
Q

where is glycerol metabolised?

A

liver

37
Q

name the 3 ketone bodies produced in the body

A
  • acetoacetate
  • acetone
  • beta-hydroxybutyrate
38
Q

how are ketone bodies removed?

A
  • picked up by cells and are converted into acetyl CoA which can then enter the TCA cycle
  • ketonuria (excreted via the urine)
39
Q

how can acetone be removed?

A

-excreted via the lung through ventilation

40
Q

synthesis of ketone bodies requires 2 things. Name them

A
  1. fatty acids to be available for oxidation in the liver and lipolysis in adipose tissue
  2. low plasma insulin/glucagon ratio (i.e. low levels of insulin)=activates lyase and inhibits reductase
41
Q

What 4 things are catabolised to form acetyl CoA?

A

fatty acids, alcohol, sugars and some amino acids

42
Q

What is glucose 6 phosphate dehydrogenase deficiency and what kind of inheritance is it?

A

Deficiency in enzyme producing NADPH

  • X linked recessive
  • reduced activity in RBC due to point mutation in gene coding for enzyme
  • increase in glutathione, s-s bond formation and thus heinz bodies produced and premature RBC death
43
Q

How many molecules of ATP are produced in chemiosmosis from one molecule of glucose by NADH and FADH? Therefore how much ATP is produced in total from one glucose?

A

32 from NADH and FADH
4 ATP (2 from glycolysis,2 from TCA cycle)
=36

44
Q

How much NADH enters oxidative phosphorylation per one glucose and how much from each part of respiration?

A

Glycolysis-2
2xPyruvate to acetyl CoA-2
2xacetyl CoA in TCA cycle-6
Total=10

45
Q

PDH requires various co factors and…..provides these factors. Fill the gap with the substance that PDH is sensitive to when deficient.

A

Vitamin B1

46
Q

What do cyanide and carbon monoxide do in oxidative phosphorylation?

A

Block flow of electrons
Therefore no p.m.f
No ATP synthesis

47
Q

Genetic defects in proteins encoded by mtDNA (protein transport complexes and ATP synthase) causes….

A

Decrease in electron transport and ATP synthesis

48
Q

Where is TAG stored?

A

Adipose tissue

49
Q

What 3 situations is TAG utilised in?

A

Prolonged exercise,starvation and pregnancy

50
Q

What do fatty acids use to transport themselves across the inner mitochondrial membrane?

A

Carnitine shuttle

51
Q

What enzyme catalyses the linking of fatty acid to coenzyme A?

A

Fatty acyl CoA synthase

52
Q

Describe the carnitine shuttle by filling the gaps

  1. The fatty acyl CoA starts in the…..
  2. it then attaches to ……by cleaving off…..and becoming….using the enzyme…..
  3. It then moves into the matrix where the reverse of the above occurs
  4. The same enzyme….allows….to re attach and form….,leaving….which moves back into the intermembrane space to be used again
A
  1. Inter membrane space
  2. Carnitine,Co enzyme A, acyl carnitine, CAT (carnitine acyl transferase)
  4. CAT, coenzyme A,fatty acyl co A, carnitine
53
Q

What does beta oxidation of fatty acids produce and where are they used in the resp pathway?

A
  • acetyl CoA (TCA cycle)

- FADH2,NADH,H+ (used in oxidative phosphorylation/electron transport chain)

54
Q

Which 3 places does beta oxidation not occur?

A

Brain,rbc and wbc

55
Q

What enzyme catalyses the conversion of glycerol to glycerol phosphate? Which then converts to DHAP (dihydroxyacetone phosphate) which turns into glyceraldehyde 3 phosphate for glycolysis

A

Glycerol kinase (as it becomes a phosphate)

56
Q

Which organ synthesises ketone bodies?

A

Liver

Metabolism (14 decks)

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