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BM210 > creating energy > Flashcards

creating energy Flashcards

this includes absorptive + post-absorptive states and ATP synthase and electron transport chain

1
Q

obviously you need to eat for energy, what is ‘food’ made up of?

A

carbohydrates
proteins
fats
vitamins and minerals - these don’t need to be broken down, they’re absorbed as they are
roughage and water - these go straight through the body, you don’t actually get any energy from these

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2
Q

where are monosaccharides absorbed through?

A

they’re absorbed in the small intestine

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3
Q

what is the simple definition of glycolysis?

A

its the breakdown of 1 glucose into 2 ATP whilst constantly taking in oxygen

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4
Q

what happens in glycolysis if there isn’t enough oxygen?

A

the pyruvate turns into lactate and there isn’t any further breakdown of glycolysis

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5
Q

what are the different steps of the breakdown of glucose called?

A

phosphoryl transfer
aldose-ketose isomerisation
aldol cleavage
phosphoryl shift
dehydration

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6
Q

what happens to the overall comporsition of glucose in glycolysis?

A

it stays the same but the position of the molecules changes

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7
Q

what happens in phosphoryl transfer?

A

a phosphoryl group from ATP and an alcohol are transferred, then the alcohol gives up the H whilst the ADP and phosphate are made

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8
Q

what happens in aldose-ketose isomerisation?

A

glucose is converted into fructose (or vice versa)
the H on the alcohol is transferred to the oxygen in the aldehyde group and that then transforms the original group into a carbonyl and the aldehyde turns into an alcohol

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9
Q

what happens in aldol cleavage?

A

the C-C bond splits to make an aldehyde and a ketose

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10
Q

what happens in phosphoryl shift?

A

the phosporyl group moves from the oxygen to an alcohol oxygen in the same molecule
the alcohol H is removed and it binds to the oxygen that was bonded to the phosphate before and the phosphate moves position

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11
Q

what happens in dehydration in glycolysis?

A

water is removed from the alcohol to make C=C in the original molecule

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12
Q

what is the redox reaction in glycolysis?

A

NAD+ is reduced and phosphate is oxididised

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13
Q

what does endolase do?

A

it removes water to make an energy rich molecule

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14
Q

what is formed by glycolysis?

A

pyruvate and 2x ATP

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15
Q

what is the net reaction of glycolysis?

A

D-glucose + 2x (NAD+) + 2x Pi > pyruvate + 2x ATP + 2x NADH + 2x (H+) + 2x H2O

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15
Q

if there was no regeneration of NAD+, what would happen to glycolysis?

A

the pathway would stop becuase there needs to be constant regeneration to give a constant cycle of ATP

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16
Q

what is the dual role of the glycolytic pathway?

A

the degradation of glucose to make ATP and it frees up the building blocks for synthetic reactions i.e. fatty acids

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17
Q

what is the commited step?

A

it the point where glycolysis HAS to happen

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18
Q

how does hexokinase work as a control site for glycolysis?

A

it can be inhibited by glucose-6-phosphate

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19
Q

how does phospofructokinase work as a control site for glycolysis?

A

committed step- inhibition is done by ATP, citrate and low pH
activation is by- AMP and fructose-2-phosphate

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20
Q

how does pyruvate kinase work as a control site for glycolysis?

A

it can be inhibited by ATP and alanine
it can be activated by fructose 1,6-biphosphate

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21
Q

what happens if theres a lot of citrate?

A

no more is produced because of positive feedback as its a bit like an end-product later on

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22
Q

what happens if theres a lot of lactate present?

A

production stops because the presence of it affects the pH so you need to stop it before too much of it is produced

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23
Q

what happens in glycolysis if theres a lot of AMP?

A

glycolysis has to happen

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24
Q

what happens in glycolysis if theres a lot of ATP and alanine?

A

glycolysis is inhibited

25
Q

what type of activation happens in glycolysis as a result of pyruvate kinase?

A

feed forward activation

26
Q

what is fructose 1,6-biphosphate made by?

A

phosphofructokinase 2

27
Q

what is phosphofructokinase 2?

A

its a bifunctional enzyme responsible for the synthesis and hydrolysis of phosphofructotinese-phospho-fructo-biphosphate from fructose-2,6-biphosphate

28
Q

how is fructose-1,6-biphosphate regulated?

A

its got 2 domains and only one can be active at once
the reciprocal form is regulated by the phosphorylation of serine 460 by PKA
the phosphorylated form means that phosphatase is active
the phosphorylated form means that the kinase is active
fructose-1,6-biphosphate is simple to activate and deactivate

29
Q

what are the diverse fates of pyruvate?

A

if theres enough oxygen, it can form acetyl CoA
NAD+ can be regenerated when going from pyruvate to lactate
it can also form acetaldehyde which can then form ethanol

30
Q

what happens in lactate formation?

A

pyruvate is reduced and NADH is oxidised
NAD+ is also regenerated in this process

31
Q

what is lactate fermentation?

A

this happens in muscles when there’s not enough oxygen

32
Q

why is lactate fermentation a dead-end in metabolism?

A

it produces an oxygen debt

33
Q

what cells undergo glucogenesis or get rid of lactate by turning it into another molecule?

A

cardiac muscles turn lactate into pyruvate
liver cells also turn it into pyruvate and then into glucose through glucogenesis (but it uses 6x ATP to turn pyruvate into glucose)

34
Q

what does the body have to do to get rid of the lactate?

A

it has to take in more oxygen so that the lactate is oxidised

35
Q

what is the reaction of pyruvate dehydrogenase multi-enzyme complex?

A

mitochondrial oxidative decarboxylation of pyruvate

36
Q

what does the decarboxylation of pyruvate produce?

A

2x carbon alcohols with reduction NAD+ into NADH

37
Q

where are fatty acids synthesisied?

A

in the cytoplam in the ‘fed’state when more carbohydrate is available than is needed for the TCA cycle

38
Q

what is glycogen used as?

A

it used as carbohydrate storage

39
Q

what is bound to the glucose on the reducing end of the glycogen that makes it not free?

A

glycogenin is bound to it as a beta-linkage to a tyrosine residue at the surface

40
Q

what does glycogenin do?

A

it’s a glycosyl-transferase which sits as a dimer in the core of glycogen
it acts as a primer so that further glucose monomers can be added and it transfers one glucose molecule to another
all its branches can be used to cleave off glucose if its needed
it can bind glucose onto an H group of tyrosine 194

41
Q

what are glycogen granules?

A

they contain all the enzymes of glycogen synthesis and degradation and actual glycogen in them

42
Q

how does the structure of glycogn help it to mobilise glucose?

A

the many non-reducing end-branches of glycogen help its fast synthesis and catabolism
all the end branches can be used to chop off other parts of glucose to make it usable

43
Q

what is the name of the readily mobilised form of glucose?

A

glycogen

44
Q

what maintains blood sugar levels?

A

a controlled release of glucose from glycogen

45
Q

where is the main storage of glycogen in the body?

A

iin the liver and skeletal muscles
8-10% of the flash weight in liver hapocytes is glycogen
the uterus also stores glycogen in pregnancy

46
Q

what are the stages of glycogen anabolism and explain them?

A

initiation - this is catalysed in an autocatalytic manner by glycogenin
elongation- this is catalysed by glycogen synthase along with branching enzyme
glycogenin does the first steps of linking glycogen and is an enzyme involved in glycogen synthesis

47
Q

what is glycogen synthase?

A

its the main enzyme involved in glycogen polymerisation and only adds to an existing chain of 8 or more glucose residues (in the elongation stage of glycogen anabolism

48
Q

what regulates the activity of glycogen synthase?

A

its regualted by covalent modifications and an allosteric mechanism

49
Q

what phosphorylates glycogen synthase and what does this cause?

A

PKA (protein kinase A) and glycognen kinase 3
phosphorylation converts the active A form into an inactive B form
the B form is still active when there’s a high level of allosteric activator glucose-6-phosphate present

50
Q

what is the immediate precursor for glycogen synthesis?

A

UDP-glucose (urindine diphosphate glucose)
this is an activated form of glucose and its the immediate precursor for glycogen synthesis

51
Q

what is the general rule for nucleotide diphosphate sugars?

A

they’re precursors for the synthesis of complex carbohydrates (including complex carbohydrates and chains of glycoproteins

52
Q

what is mutase

A

its a type of isomerase
it takes something and attaches it to anther part of it

53
Q

what is the equation for the formation of UDP-glucose? (hint there’s 2 equations)- this isn’t the overall equation

A

glucose-1-phosphate + UTP ↔UDP-glucose + PPi
PPi + H2O > 2 Pi (inorganic pyrophosphate)

54
Q

what is the overall equation for the formation of UDP-glucose?

A

glucose-1-phosphate + UTP > UDP-glucose + 2Pi

55
Q

is the reaction of creating UDP-glucose reversible?

A

no. the spontaneous hydrolysis of the P bond in PPi driver the overall reaction and makes it irreversible

56
Q

what uses energy in glycogen synthesis?

A

the hydrolysis of pyrophosphate as one P bond is broken per glucose residue

57
Q

in glycogen synthesis, how is an alpha-1,4-glycosidic linkage formed?

A

it formed by glucose residues being addded to the non-reducting terminal residues of glycogen
UPD-glucose is the substrate and UPD is released as a reaction product

58
Q

where are the branches coming from in glycogen synthesis?

A

they’re formed by the branching enzyme amylo (1,4→1,6) transglycosylase
a block of 7 residues from the non-reducing end is transferred to a more interior site to create a branch
the block must have the non-reducing terminus and it attaches them by an alpha-(1,6)-linkage
the branch can’t be closer than 4 residues from the nearest branch

59
Q

why is branching important in glycogen?

A

in incraeses its solubility
a large osotically inactive storage form of glucose can be created
it can create lots of terminal residues
it increases the rate of glycogen synthesis and degradation

60
Q

what are terminal residues?

A

theyre the sites of action of glycogen phophorylase and glycogen synthase

61
Q

why would it be a problem if glycogen was osmotically active?

A

because it would cause lots of osmotic activity causing you to bloat and possibly explode

BM210 (13 decks)

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