glycolysis n krebs Flashcards by Maryam Garkuwa

why do we need glycerol 3 phosphate shuttle?

ETC is located in the inner membrane of mitochondria which is impermeable to the NADH that has been produced OUTSIDE the mitochondria (like in glycolysis) Howver the NADH produced in the mitochondria is fine because its already there

NADH is used to reuced DHAP giving us glycerol 3 p. by the enzyme glycerol 3 p DH 1
A similar enzyme is located in the outer mitchondrial membrane which glycerol 3 phosphate 2 uses FAD to take the H from glycerol 3 phosphate, reforming DHAP
FADH2 gives the H to co enzyme q

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how many NADH produced by glycolysis

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substrate level phosphorylation

in glycolysis when we form ATP when 1,3 biphosphoglycerate gives a phosphate to ADP we form overall 2 atps and also the last step with pyruvate kinase

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how does glucose enter the cell

through NA glucose transporter, examples of secondary active transport because the na gradient was created by a pump

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GLUT 1 
GLUT 2
3
4
5

all cells but especially brain and RBC
liver,SI,kidney (hyper) low affinity high KM
3.Brain neurons (hypo) high affinity but low Km
adipose tissue and muscle
5 enterocytes

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what is the fate of glucose in liver

enzyme glucokinase makes glucose 6 phospate and then proceeds to make glycogen

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glucose and pancrease

glucose enters glycolysis, atp produced increases ca2+ levels and then triggers insulin release by exocytosis

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regulatory enzymes of glycolysis

ALL OF THE KINASES
1. hexokinase- inhibited by its products
2. phosphofructokinase
- :( ATP
:( reducing equivalents
:( citrate
:) activated by fructose 2,6 bisphosphate
3. PK
AAAF
:( alanine, acetyl coa , atp, fatty acids
:) fructose 1,6 biphosphate

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comparison of hexokinase and glucokinase

found in all cells
not specific to just glucose
inhibited by product glucose 6 p
high affinity for glucose
has 4 isoforms
not activated by insulin

found only in liver
low affinity for glucose
not inhibited by its product
is most effective when the level of glucose is high in the blood so after a meal which means its activated insulin

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committed step in glycolysis

phosphofructokinase

highly regulated
highly exergonic reaction

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fate of pyruvate

depends on whether its anaerobic or aerobic

anaerobic- produce lactic acid (RBC, muscles) LDH
aerobic_ oxidative decarboxylation of pyruvate to acetyl co- A

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what is an additional function of pyruvate

serves as a fuel source for cardiac muscle and brain nerurons

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phosphofructokinase

major regulatory enzyme
- :( citrate (makes sense because its a catabolic process)
:) fructose 2,6 bisphosphate (is an indicator of high glucose level)
:( ATP + reducing equivalents

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fructose 1,6 bisphosphate and fructose 2,6 biphosphate

1,6 - :) PK

2,6 :) phosphofrcutokinase

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regulation of pyruvate kinase

AAAF- atp,alanine,acetyl coa , fatty acids
:) fructose 1,6 bisphosphate
similar to glycogen synthase is active in its OH form

insulin - activate
glucagon-inactivate

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when do you mention the glycerol 3 phosphate

glycolysis

fatty acid synthesis

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what is the point of citrate shuttle and explain it (draw)

need to get the acetyl coa from mitochondria to cytoplasm for e.g fatty acid synthesis

in mitochondria acetyl coa+ oxaloacetate to make citrate
citrate leave mitochondria to go cytoplasm where its cleaved back to products (citrate lyase)

the oxaloacetate, its goal is to be converted back to pyruvate.

reverse of krebs———malate (malate DH)
Malic enzyme - produces Nadph gives pyruvate
malate+NADP—–pyruvate co2 + NADPH
pyruvate translocase transports to mitochondria

anoplerotic reaction

pyruvate carboxylase forms oxaloacetate

how do we reverse glycolysis

7 of the enzymes are the same apart from 3. 2/3 use simple hydrolysis reactions and the other one is split into 2 enzymes

glucokinase
glucose 6 phosphatase
phosphofructokinase
fructose 1, 6 biphosphatase
PK
pyruvate to oxaloacetate =pyruvate carboxylase

oxaloacetate —– phosphoenolpyruvate (phosphoenolpyruvate carboxykinase)

when do you mention the malate shuttle

glycolysis

gluconeogeneisis

fructose 1, 6 bisphosphatase

one of the bypass enzymes involved for gluconeogenesis
it breaks down fructose 1, 6 phosphate into fructose 6 phosphate

:) citrate
:(frucots 2, 6 bisphosphate because that is AN IDICATOR OF HIGH GLUCOSE AVAILABILITY

what is the role of fructose 2,6 biphosphate

is an indicator of high glucose ability

pyruvate carboxylase

a mitochondrial enzyme
b7
atp
needs acetyl coa (because theres no point of making oxaloacetate if there is no acetyl co a to facilitate krebs

where does gluconeogenesis occur

cytoplasm!

malate aspartate shuttle

In order for gluconeogenesis to occur need oxaloacetate which is produced in the mitochondria but gluconeogenesis happens in the cytosol. but oxaloacetate cannot leave through the inner mitochondrial membrane. route 1- converted to malate route 2 _ aspartate

when do you mention the malate shuttle

gluconeogenesis

deficiencies regarding gluconeogenesis

- fructose 1,6 biphosphatase blocking of gluconeogenesis leading to hypoglycemia and LACTIC ACIDOSIS between meals the blood glucose is maintained only by glycogenolysis Hypoglycemia of the neonate -brain consumes a lot of glucose -they have small amount of adipose tissue for an alternative fuel source the enzymes of gluconeogenesis may not be completely functional at this time -smaller glucose stores

PFK1 isoforms

muscle constitutive high glycolysis during exercise . liver - inducible - by insulin specially activated by fructose 2, 6 biphosphaste

name the products of krebs

citrate cis aconitate isocitrate a ketoglutarat

how many atps directly from krebs

how many indirect atps

11 cos 3 Nads 1 fad

which enzyme uses fad as a cofactor for krebs

succinate dh

where do we generate the direct atp from

from the cleavage of succinyl coa````````````

substrates and products of krebs

substrates (basically first step) 1. OAA ACETYL COA WATER products - nadh - fadh2 - co2 - atp

regulation of krebs

3 irreversible reactions 1. citrate synthase 2. isocitrate DH 3. alpha k glutarate DH

PDH regualtion

OH IM PYRUVATE AND IM ACTIVE:) :(atp + reducing equivalents and acetyl coa :) promoted by any sudden demand upon the cell signalled by calcium

anoplerotic reaction

chemical reactions that form intermediates of a metabolic pathway like krebs. Because the intermediates don't just have the sole purpose of making atp but other things to

what other roles does oxaloacetate have

- glucose | - aa (aspartate)

functions of krebs

1. ATP | 2. Building blocks for other things

what do the intermediates form in krebs

``` citrate- fats a k glutatarate- aa glutamine and glutamate and GABA succinyl- heme+porphyrin oxaloacetate- aa aspartate + glucose malate-glucose ```

oxidative phosphorylation

process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms