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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
what happens in glycolysis if theres a lot of ATP and alanine?
glycolysis is inhibited
25
what type of activation happens in glycolysis as a result of pyruvate kinase?
feed forward activation
26
what is fructose 1,6-biphosphate made by?
phosphofructokinase 2
27
what is phosphofructokinase 2?
its a bifunctional enzyme responsible for the synthesis and hydrolysis of phosphofructotinese-phospho-fructo-biphosphate from fructose-2,6-biphosphate
28
how is fructose-1,6-biphosphate regulated?
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
what are the diverse fates of pyruvate?
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
what happens in lactate formation?
pyruvate is reduced and NADH is oxidised NAD+ is also regenerated in this process
31
what is lactate fermentation?
this happens in muscles when there's not enough oxygen
32
why is lactate fermentation a dead-end in metabolism?
it produces an oxygen debt
33
what cells undergo glucogenesis or get rid of lactate by turning it into another molecule?
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
what does the body have to do to get rid of the lactate?
it has to take in more oxygen so that the lactate is oxidised
35
what is the reaction of pyruvate dehydrogenase multi-enzyme complex?
mitochondrial oxidative decarboxylation of pyruvate
36
what does the decarboxylation of pyruvate produce?
2x carbon alcohols with reduction NAD+ into NADH
37
where are fatty acids synthesisied?
in the cytoplam in the 'fed'state when more carbohydrate is available than is needed for the TCA cycle
38
what is glycogen used as?
it used as carbohydrate storage
39
what is bound to the glucose on the reducing end of the glycogen that makes it not free?
glycogenin is bound to it as a beta-linkage to a tyrosine residue at the surface
40
what does glycogenin do?
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
what are glycogen granules?
they contain all the enzymes of glycogen synthesis and degradation and actual glycogen in them
42
how does the structure of glycogn help it to mobilise glucose?
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
what is the name of the readily mobilised form of glucose?
glycogen
44
what maintains blood sugar levels?
a controlled release of glucose from glycogen
45
where is the main storage of glycogen in the body?
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
what are the stages of glycogen anabolism and explain them?
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
what is glycogen synthase?
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
what regulates the activity of glycogen synthase?
its regualted by covalent modifications and an allosteric mechanism
49
what phosphorylates glycogen synthase and what does this cause?
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
what is the immediate precursor for glycogen synthesis?
UDP-glucose (urindine diphosphate glucose) this is an activated form of glucose and its the immediate precursor for glycogen synthesis
51
what is the general rule for nucleotide diphosphate sugars?
they're precursors for the synthesis of complex carbohydrates (including complex carbohydrates and chains of glycoproteins
52
what is mutase
its a type of isomerase it takes something and attaches it to anther part of it
53
what is the equation for the formation of UDP-glucose? (hint there's 2 equations)- this isn't the overall equation
glucose-1-phosphate + UTP ↔UDP-glucose + PPi PPi + H2O > 2 Pi (inorganic pyrophosphate)
54
what is the overall equation for the formation of UDP-glucose?
glucose-1-phosphate + UTP > UDP-glucose + 2Pi
55
is the reaction of creating UDP-glucose reversible?
no. the spontaneous hydrolysis of the P bond in PPi driver the overall reaction and makes it irreversible
56
what uses energy in glycogen synthesis?
the hydrolysis of pyrophosphate as one P bond is broken per glucose residue
57
in glycogen synthesis, how is an alpha-1,4-glycosidic linkage formed?
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
where are the branches coming from in glycogen synthesis?
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
why is branching important in glycogen?
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
what are terminal residues?
theyre the sites of action of glycogen phophorylase and glycogen synthase
61
why would it be a problem if glycogen was osmotically active?
because it would cause lots of osmotic activity causing you to bloat and possibly explode

BM210 (13 decks)

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