metabolic pathways Flashcards

1
Q

anabolic reactions

A

build up molecules

require energy (ATP)

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2
Q

catabolic reactions

A

break down molecules

release energy stored in chemical bonds

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3
Q

cellular respiration

short definition

A

entire process by which ATP is generated using glucose and oxygen

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4
Q

cellular respiration

3 phases

A

glycolysis
krebs cycle
oxidative phosphorylation

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5
Q

glycolysis

A

1 glucose → 2 pyruvate

produces (net) 2 ATP and 2 NADH

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6
Q

where does glycolysis occur?

A

cytoplasm

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7
Q

does glycolysis require oxygen?

A

no!

anaerobic process

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8
Q

glycolysis: rate-determining step

enzyme

A

phosphofructokinase

fructose-6P to fructose-1,6 bisP

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9
Q

what process substituted kreb’s if oxygen is absent?

in humans

A

lactic acid fermentation

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10
Q

fermentation

A

pyruvate + NADH → lactate and NAD+

NAD+ is used again in glycolysis so more ATP can be produced

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11
Q

krebs cycle

A

pyruvute from glycolysis → acetyl-coA → cycle

produces 2 ATP, 6 NADH, and 2 FADH2 per glucose

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12
Q

glycogen

A

the stored form of glucose that’s made up of many connected glucose molecules

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13
Q

what are the bonds that connect the glucose chains of glycogen

A

alpha-1,4-glycosidic bonds

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14
Q

what are the bond that create branches in glycogen

A

alpha-1,6-glycosidic bonds

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15
Q

glycogenesis

A

formation of glycogen from glucose monomers (for storage)

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16
Q

where is most glycogen stored?

A

skeletal muscle and the liver

17
Q

glycogenolysis

A

converts glycogen back to glucose

(glycogen breaks down to glucose 1P and glucose)

18
Q

gluconeogenesis

A

the production of NEW glucose from noncarbohydrate sources (ex. fat, amino acids, lactate, pyruvate, etc.) when glycoggen stores run out

almost reverse of glycolysis; has a diff path for the 3 irr. steps

19
Q

gluconeogenesis: pyruvate to PEP

A

lactate → pyruvate → oxaloacetate → PEP

or

amino acids → oxaloacetate → PEP

note: pyruvate → OAA requires ATP, OAA → PEP requires GTP

20
Q

pentose phosphate pathway

A

glucose → glucose 6P → ribose 5P and glycolysis intermediates

21
Q

gluconeogenesis: fructose 1,6 bisphosphate → fructose 6P

enzyme

A

fructose 1,6 bisphosphatase

22
Q

gluconeogenesis: glucose 6P → glucose

A

uses enzyme glucose 6 phosphatase

(instead of hexokinase of reverse reaction)

23
Q

what are the 2 key products of the pentose phosphate pathway

A

1) ribose-5-phosphate (pentose)
2) NADHPH (phosphate)

24
Q

what is the ribose-5p from PPP used for

A

to create DNA and RNA

25
Q

what is the NADPH created in PPP used for?

A

1) donating electrons for anabolic reactions (ex. fatty acid synthesis)
2) regenerate anti-oxidants

26
Q

pentose phosphate pathway: 2 phases

A

1) oxidative phase
2) non-oxidative phase

27
Q

pentose phosphate pathway oxidative phase

A

glucose 6P → ribulose 5P

NADP+ → NADPH (x2)

28
Q

pentose phosphate pathway: nonoxidative phase

A

ribulose 5p → ribose 5P

ribose-5P is used for nucleotide synthesis to make DNA/RNA

other intermediates are metabolites of glycolysis (fructose 3P and glyceraldehye 6P)

29
Q

ATP used/released during PPP

A

NONE!

this makes PPP unique from other carbohydrate metabolism

30
Q

fatty acid synthesis

A

conversion of excess glucose → fatty acids

glucose → pyruvate → acetyl-coA (in mitochondria) → citrate → acetyl-coA (in cytoplasm) + OAA

acetyl coA → acetyl coA carboxylase (RLS) → malonyl coA → palmitic acid (fatty acid)

31
Q

fatty acid oxidation

A

fatty acids → acetyl coA

32
Q

where does fatty acid synthesis from glucose occur

A

in the cytoplasm of liver cells