metabolic pathways

Question 1

anabolic reactions

Answer 1

build up molecules

require energy (ATP)

Question 2

catabolic reactions

Answer 2

break down molecules

release energy stored in chemical bonds

Question 3

cellular respiration

short definition

Answer 3

entire process by which ATP is generated using glucose and oxygen

Question 4

cellular respiration

3 phases

Answer 4

glycolysis
krebs cycle
oxidative phosphorylation

Question 5

glycolysis

Answer 5

1 glucose → 2 pyruvate

produces (net) 2 ATP and 2 NADH

Question 6

where does glycolysis occur?

Answer 6

cytoplasm

Question 7

does glycolysis require oxygen?

Answer 7

no!

anaerobic process

Question 8

glycolysis: rate-determining step

enzyme

Answer 8

phosphofructokinase

fructose-6P to fructose-1,6 bisP

Question 9

what process substituted kreb’s if oxygen is absent?

in humans

Answer 9

lactic acid fermentation

Question 10

fermentation

Answer 10

pyruvate + NADH → lactate and NAD+

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

Question 11

krebs cycle

Answer 11

pyruvute from glycolysis → acetyl-coA → cycle

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

Question 12

glycogen

Answer 12

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

Question 13

what are the bonds that connect the glucose chains of glycogen

Answer 13

alpha-1,4-glycosidic bonds

Question 14

what are the bond that create branches in glycogen

Answer 14

alpha-1,6-glycosidic bonds

Question 15

glycogenesis

Answer 15

formation of glycogen from glucose monomers (for storage)

Question 16

where is most glycogen stored?

Answer 16

skeletal muscle and the liver

Question 17

glycogenolysis

Answer 17

converts glycogen back to glucose

(glycogen breaks down to glucose 1P and glucose)

Question 18

gluconeogenesis

Answer 18

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

Question 19

gluconeogenesis: pyruvate to PEP

Answer 19

lactate → pyruvate → oxaloacetate → PEP

or

amino acids → oxaloacetate → PEP

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

Question 20

pentose phosphate pathway

Answer 20

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

Question 21

gluconeogenesis: fructose 1,6 bisphosphate → fructose 6P

enzyme

Answer 21

fructose 1,6 bisphosphatase

Question 22

gluconeogenesis: glucose 6P → glucose

Answer 22

uses enzyme glucose 6 phosphatase

(instead of hexokinase of reverse reaction)

Question 23

what are the 2 key products of the pentose phosphate pathway

Answer 23

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

Question 24

what is the ribose-5p from PPP used for

Answer 24

to create DNA and RNA

Question 25

what is the NADPH created in PPP used for?

Answer 25

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

Question 26

pentose phosphate pathway: 2 phases

Answer 26

1) oxidative phase
2) non-oxidative phase

Question 27

pentose phosphate pathway oxidative phase

Answer 27

glucose 6P → ribulose 5P

NADP+ → NADPH (x2)

Question 28

pentose phosphate pathway: nonoxidative phase

Answer 28

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)

Question 29

ATP used/released during PPP

Answer 29

NONE!

this makes PPP unique from other carbohydrate metabolism

Question 30

fatty acid synthesis

Answer 30

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)

Question 31

fatty acid oxidation

Answer 31

fatty acids → acetyl coA

Question 32

where does fatty acid synthesis from glucose occur

Answer 32

in the cytoplasm of liver cells