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year 1 - dentistry > glycolysis > Flashcards

glycolysis Flashcards

1
Q

what process is every cell able to generate ATP

A

glycolysis even in anaerobic conditions

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2
Q

where does glycolysis occur

A

in the cytoplasm, cytosol

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3
Q

what is the first step of glycolysis and which enzyme is involved

A
  • phosphorylation of glucose to glucose 6 - phosphate

- enzyme hexokinase

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4
Q

what is the second step - after formation of glucose 6 -phosphate

A
  • each glucose 6 phosphate is oxidised by a series of reactions to two pyruvate molecules
  • generating two molecules of NADH and two molecules of ATP
  • the ATP is generated by direct transfer of the phosphate groups (substrate level phosphorylation)
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5
Q

in aerobic conditions what happens to the pyruvate after being formed from glucose 6 phosphate

A
  • the pyruvate is oxidised to produce CO2 - maintains ph balance and ATP via the TCA cycle and oxidative phosphorylation
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6
Q

what happens in anaerobic conditions and what enzyme is involved

A
  • cells have to resort to anaerobic glycolysis
  • this is important to regenerate the NAD so glycolysis can occur
  • involves reducing pyruvate to lactate
  • enzyme lactate dehydrogenase
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7
Q

what happens when a lot of lactate is produced

A
  • when enough lactate is produced it can use lactate acidaemia (making muscles burn)
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8
Q

what is the first step in the TCA cycle in the presence of oxygen - what happens to the pyruvate and by what enzyme

A
  • pyruvate is converted into acetyl co - a
  • enzyme pyruvate dehydrogenase (PDH)
  • it is a complex of three enzymes
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9
Q

how does the TCA cycle contribute to generating majority of ATP

A
  • by oxidising acetyl co - A to the electron donors NADH and FADH2 which enter the electron transport chain
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10
Q

why does ATP drive most processes

A
  • due to its high energy phosphoanhydride bonds between the phosphate groups
  • phosphate groups are negatively charged and repel each other - meaning lots of energy is required to keep them together and energy is released when one of the phosphate groups is released
  • the release of a phosphate group converts ATP to ADP
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11
Q

what is oxidative phosphorylation (how is ADP converted back into ATP)

A
  • ADP converted to ATP using the enzyme ATP synthase
  • using reduced co enzymes formed during glycolysis and the TCA cycle in the ETC
    = oxidative phosphorylation
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12
Q

what is most of the energy generated in the TCA in the form of what

A
  • reduced enzymes NADH and FADH2
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13
Q

in oxidative phosphorylation was does the electron transport chain do to NADH and FADH2

A
  • NADH and FADH2 is oxidised and donates the electron to O2 which is reduced to H20
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14
Q

the energy which is generated from the reduction of O2 to H20 what is it used for

A
  • used to phosphorylate ADP
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15
Q

how is ATP generated from ADP via the electron transport chain

A
  • the etc contains proteins which span the inner membrane of the mitochondria (protein complexes 1, 3, 4)
  • electrons pass through these proteins - oxidation - reduction reactions whilst at the same time pumping protons (H+ ions) across the inner mitochondrial membrane (from matrix towards outside)
  • this creates an electrochemical gradient, which protons return to the matrix, passing through a pore in ATP synthase
  • shape change of ATP synthase as protons pass through - synthesising and releasing ATP
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16
Q

what is uncoupling of proton movement from atp generation

A
  • allowing protons to move back across the inner mitochondrial membrane into the matrix - generating heat but no ATP is produced
  • occurs in brown fat cells of young babies
17
Q

what is the enzyme phosphofructokinase - 1

A
  • regulatory enzyme
  • allosteric regulation either speeding up its activity or slowing it down
  • regulated according to the availability of substrate or product
18
Q

what do yeast and plants form and what enzymes are involved

A
  • ethanol produced
  • pyruvate - acetaldehyde
    enzyme pyruvate decarboxylate
  • acetaldehyde - ethanol
    enzyme alcohol dehydrogenase
19
Q

where is lactate converted back to glucose

A
  • lactate is toxic and forms lactic acid - changing blood pH
  • lactate goes to liver and converted back to glucose
20
Q

which two bacterias form lactic acid in mouth - anaerobic fermentation of sugar

A
  • lactobacillus
  • streptococcus mutans
    a lowered ph promotes demineralisation leading to decay
21
Q

where does oxidative phosphorylation occur

A
  • inner membrane of mitochondria
22
Q

what is NAD+

A
  • electron accepting co - enzyme

- not bound to an enzyme - once its reduced it leaves enzyme and can inhibit others

23
Q

what is FAD

A
  • electron accepting co enzyme
  • only accepts single electrons
  • tightly bound to enzymes
24
Q

what is purpose of atp synthase

A
  • generates ATP
  • multi subunit enzyme
  • spans inner mitochondrial enzyme
  • F1 unit contains 3 catalytic sites
  • F0 unit forms a rotor
  • influx of protons turns rotor, changing conformation of active site in F1 unit release an ATP molecule
25
Q

what is electron flow dependent on in the electron transport chain

A
  • proton pumping
    ; electron movement requires proton pumping
    ; needs proton to return to matrix
  • uncoupling means protons return back to the matrix without passing through the ATP synthase
26
Q

what are the 3 types of couplers

A
  • chemical
  • physiological
  • proton leak
27
Q

chemical uncouplers

A
  • chemicals which transport protons across inner membrane
  • destroy proton gradient
  • no ATP
28
Q

physiological couplers

A
  • uncoupling proteins form channels through inner membrane
  • protons pass through these
  • thermogenin
29
Q

proton leak

A
  • low level leaks across inner membrane

- more than 20% metabolic energy needed to overcome this and maintain proton gradient

30
Q

inhibitors

A
  • inhibition of complexes blocks passage of electrons and proton pumping
  • cyanide blocks cytochrome oxidase and stops electron flow therefore blocks proton pumping and atp synthesis
31
Q

OXPHOS disease

A
  • mitochondrial DNA encodes some of this protein in the complexes of oxidative phosphorylation
  • mitochondrial dna has no repair mechanisms
  • mutations are therefore permanent
  • resulting in faulty complexes
  • leads to a number of diseases affecting tissue with high energy demand = OXPHOS disease

year 1 - dentistry (24 decks)

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