carbohydrate metabolism glycolysis and the TCA Flashcards

1
Q

what is an anabolic pathway

A

pathway concerned with the synthesis of cellular components

makes bonds

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2
Q

what is a catabolic pathway

A

pathway that is involved with the degradation of cellular components
exergonic process which breaks bonds
increases entropy

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3
Q

what is oxidation

A

loss of electrons
gain of oxygen
loss of hydrogen

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4
Q

what is reduction

A

gain of electrons
loss of oxygen
gain of hydrogen

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5
Q

where are the acid anhydride bonds located in ATP

A

they are located between the phosphate-oxygen-phosphate in the triphosphate molecule of ATP

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6
Q

where are the phosphate ester bonds located in the ATP molecule

A

between the ribose oxygen and the phosphate of the triphosphate group

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7
Q

why is ATP the currency of energy

A

due to its unstable energy rich nature of the acid anhydride bond

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8
Q

why are the acid anhydride bonds full of energy

A

due to the charge repulsion because of the adjacent phosphate groups
and because of the resonance of phosphate ions

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9
Q

which molecules have energy

A

sugar
starch
protein

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10
Q

what is oxidation according to biochemical definitions

A

we can remove an electron and protons(H+ ions)

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11
Q

what is TCA

A

tricarboxylic acid cycle/krebs cycle/citric acid cycle

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12
Q

what is the most common fuel in mammals

A

glucose

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13
Q

what is the only fuel the brain uses

A

glucose

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14
Q

describe the structure of glucose

A

it is a 6 carbon sugar that has a tendency to remain in ring formation

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15
Q

what occurs in glycolysis

A

glucose broken into 2 molecules of pyruvate

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16
Q

what products are produced when glucose is fermented

A

ethanol
C02
lactate

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17
Q

what products are produced when we have complete oxidation of glucose

A

6h20 and 2c02

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18
Q

what are microbes called when they can survive in no oxygen

A

facultative anaerobes

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19
Q

what do animals display

A

anerobiosis

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20
Q

what is anaerobiosis

A

tolerate small amounts of anaerobic activity

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21
Q

where does glycolysis occur

A

in the cytosol

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22
Q

what are the two phases of glycolysis

A

the investment phase and the return phase

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23
Q

what occurs in the investment phase of glycolysis

A

we use 2 molecules of ATP to produce fructose 1,6 bisphosphate

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24
Q

what occurs in the return phase of glycolysis

A

we get some ATP BACK and pyruvate is produced

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25
Q

how does glucose enter the cell

A

via transport proteins GLUT4

26
Q

what is the first stage of glycolysis

A

glucose enters the cell

glucose reacts with ATP- phosphorylated withe the enzyme hexokinase to produce glucose-6 phosphate

27
Q

why can glucose 6 phosphate not get out of the cell

A

because it is charged

28
Q

why can glucose 6 phosphate be broken down easily

A

due to the instability of the molecule due to the negative charge

29
Q

what conditions does hexokinase require

A

magnesium- type 2 and crowns disease can lack this

30
Q

which enzyme catalyses the isomerisation of G6P

A

phosphoglucose isomerase

31
Q

what is isomerism

A

the same empirical formula but a change in the shape

32
Q

what are the stages of isomerism of g6p

A
  1. first the carbon 6 ring is opened- has an aldove
  2. catalyse isomerisation occurs and the aldose is converted to a ketose
  3. formation of the cyclic fructose 6 phosphate
33
Q

what then happens to fructose 6 phosphate

A
  1. it reacts with ATP and phosphofructokinase(PFK) to produce fructose1,6 bisphosphate, ADP, H+
  2. this reacts with aldolase to produce glyceraldehyde 3 phosphate (gap) and dihydroxyacetone phosphate(DHAP)
34
Q

what is the rate determining step for glycolysis

A

the phosphorylation of fructose 6 phosphate to fructose 1,6 phosphate by phosphofructokinase

35
Q

what are the two products aldolase produces

A

GAP AND DHAP

36
Q

how do we convert dihydroxyacetone phosphate into glyceraldehyde 3 phosphate

A

by the enzyme triose phosphate isomerase which forms aldose and then forms glyceraldehyde 3 phosphate

37
Q

what is the ATP consuming summary

A
  1. hexokinase
  2. phosphoglucose isomerase
  3. phosphofructosekinase
  4. aldose
  5. triose phosphate isomerase
38
Q

what does the second stage of glycolysis start with

A

glyceraldehyde 3 phosphate +NAD + pi and the enzyme glyceraldehyde 3 phosphate dehydrogenase to form 1,3bisphosphogltcerate + NADH+H+

39
Q

what molecule has a high phosphorylation transfer potential

A

1,3bisphosphogltcerate

40
Q

what happens to the 1,3 bisphosphogltcerate

A

reacts with ADP+H+ and phosphoglycerate kinase to from 3 phosphoglycerate and ATP

41
Q

what then happens to 3 phosphoglycerate

A

it reacts with phosphoglycerate mutate to form 2 phosphoglycerate

42
Q

what does 2 phosphoglycerate react with

A

endolase and a hydrolysis reaction to form ATP and pyruvate

43
Q

what can the reversible reaction of pyruvate form

A

phophophenolpyruvate (PEP) +ADP+H+

44
Q

which molecule must be regernated from the metabolism of pyruvate

A

NAD

45
Q

at the end of glycolysis what do we have

A

used 2 ATP molecules

created 4 ATP molecules THEREFORE net gain of 2ATP, 2PYRUVATE

46
Q

how can NAD be regenerated

A
  1. pyruvate to lactate
  2. pyruvate to acetylCoA
  3. pyruvate to acetaldehyde-> ethanol which oxidises NADH
47
Q

how does pyruvate become acetyl coenzyme A

A

by the enzyme pyruvate dehydrogenase

and through oxidative decarboxylation

48
Q

where is acetylcoenzyme A found

A

in the matrix of the mitochondria

49
Q

what is the main role of the krebs cycle

A

to harvest high energy electrons from carbon compounds

50
Q

what is the first stage of the krebs cycle

A

citrate synthase

51
Q

how is citrate synthesised in the cycle

A

acetylcoA(2C) enters and is condensed and reacts with oxaloacetate(4C) to form citrate COA and then the coA leaves the molecule to form citrate(6C)

52
Q

what is the second stage of the krebs cycle

A

citrate first undergoes dehydration, then isomerisation to form cis citrate and then hydration again to form isocitrate. aconitase reacts in both steps

53
Q

what is the third stage of the krebs cycle

A

isocitrate(6C) undergoes oxidative decarboxylation which forms alpha ketoglutarate(5C) with the help of the enzyme isocitrate dehydrogenase
ALSO RELEASES NADH

54
Q

what is the rate determining step of the krebs cycle

A

the overall formation of a ketoglucarate

55
Q

WHAT IS STAGE 4 OF THE KREBS CYCLE

A

oxidative decarboxylation from a ketoglutarate(5C) to succinylCOA(4C)
RELEASES NADH

56
Q

what is step 5 of the krebs cycle

A

substrate level phosphorylation from Succinyl COA to succinate
this forms ATP with the help of the enzyme succinylCOA synthase

57
Q

what is step 6 of the krebs cycle

A

dehydrogenation/oxidation from succinate(4C) to fumarate (4C)
releasing FADH2

58
Q

what is step 7 of the krebs cycle

A

hydration of fumarate to malate by fumerase

59
Q

what is step 8 of the krebs cycle

A

dehydrogenation/oxidation from malate to oxaloacetate with malate dehydrogenase
RELEASING NADPH

60
Q

which step of the krebs cycle is irreversible

A

1,3,4