metabolic pathways and ATP production

Question 1

where does glycolysis occur

Answer 1

cytoplasm

Question 2

is glycolysis aerobic or anaerobic

Answer 2

anaerobic

Question 3

give the basic reaction of glycolysis, including ATP and NADH

Answer 3

1x6C glucose → 2x3C pyruvate (+2ATP, 2NADH)

Question 4

what is the production of ATP an example of

Answer 4

substrate-level phosphorylation: ATP production by transfer of high energy PO4 3- group from intermediate substrate to ADP

Question 5

first stage of glycolysis and significance

Answer 5

glucose → glucose-6-phosphate + H+ (irreversible; hexokinase (glucokinase in liver); ATP → ADP)

Question 6

second stage of glycolysis

Answer 6

isomerise glucose-6-phosphate to fructose-6-phosphate

Question 7

third stage of glycolysis and significance of product

Answer 7

fructose-6-phosphate → fructose-1,6-bisphosphate (highly symmetrical; phosphofructokinase; ATP → ADP)

Question 8

in molecular nomenclature, what is the difference between “bi” and “di”

Answer 8

“bi” is not joined and “di”is joined

Question 9

fourth and fifth stages of glycolysis

Answer 9

ring opens to form 2x3C; isomerisation to form 2 glyceraldehyde-3-phosphate molecules

Question 10

sixth stage of glycolysis

Answer 10

glyceraldehyde-3-phosphate → 1,3-bisphosphoglycerate (glyceraldehyde-3-phosphate dehydrogenase; NAD+ + Pi → NADH)

Question 11

seventh stage of glycolysis

Answer 11

1,3-bisphosphoglycerate → 3-phosphoglycerate (phosphoglycerate kinase; ADP → ATP)

Question 12

eighth stage of glycolysis

Answer 12

isomerisation of 3-phosphoglycerate to 2-phosphoglycerate (phosphoglycerate mutase)

Question 13

ninth stage of glycolysis

Answer 13

2-phosphoglycerate → phosphoenolpyruvate + H2O (enolase dehydration)

Question 14

tenth stage of glycolysis

Answer 14

phosphoenolpyruvate → pyruvate (pyruvate kinase; ADP → ATP)

Question 15

what can glucose-6-phosphate be stored as

Answer 15

glycogen or pentose phosphates used for nucleotides

Question 16

what can glycogen be synthesised from

Answer 16

UDP-glucose

Question 17

how are sugars stored

Answer 17

glycogen, fatty acids and cholesterol

Question 18

when are ketone bodies used

Answer 18

when the bodt is fasting (used by brain as cannot metabolise fatty acids)

Question 19

diagram showing generation of molecules from different glycolysis and TCA intermediates

Answer 19

diagram form metabolism 9

Question 20

when does gluconeogenesis occur and what does it prevent

Answer 20

when the body is fasting or intense exercise to prevent low [glucose] which could lead to hypoglycaemic coma

Question 21

short term fasting

Answer 21

break down glycogen, release fatty acids from adipose, acetyl CoA converted to ketone bodies (used in muscle to produce glucose)

Question 22

long term (12-18 hours) fasting

Answer 22

supplies exhausted

Question 23

define gluconeogenesis

Answer 23

produces glucose from non-carbohydrate sources (lactate, amino acids, glycerol)

Question 24

is gluconeogenesis the reversal of glycolysis

Answer 24

no - requires different enzymes

Question 25

does gluconeogenesis require ATP

Answer 25

yes

Question 26

where does gluconeogenesis occur

Answer 26

liver

Question 27

diagram to show gluconeogenesis stages vs glycolysis

Answer 27

diagram from metabolism 9

Question 28

what is the common starting point in gluconeogenesis

Answer 28

oxaloacetate

Question 29

net loss of gluconeogenesis

Answer 29

6 ATP

Question 30

first stage of gluconeogenesis

Answer 30

pyruvate → oxaloacetate (pyruvate carboxylase) in mitochondria

Question 31

second stage of gluconeogenesis

Answer 31

oxaloacetate → phosphoenolpyruvate (phosphoenolpyruvate carboxykinase) in cytosol; limiting stage

Question 32

third stage of gluconeogenesis

Answer 32

phosphoenolpyruvate → G3P → fructose-1,6-bisphosphate

Question 33

fourth stage of gluconeogenesis

Answer 33

fructose-1,6-bisphosphate → fructose-6-phosphate (fructose-1,6-bisphosphatase) in cytosol

Question 34

fifth stage of gluconeogenesis

Answer 34

fructose-6-phosphate → glucose-6-phosphate

Question 35

sixth stage of gluconeogenesis

Answer 35

glucose-6-phosphate → glucose (glucose-6-phosphatase) in cytosol

Question 36

sources of pyruvate

Answer 36

lactate (via LDH) and amino acids

Question 37

source of oxaloacetate

Answer 37

ketogenic amino acids

Question 38

sources of G3P

Answer 38

phosphoenolpyruvate, glycerol → DHAP

Question 39

what happens to ATP and glucose demand in aerobic respiration

Answer 39

increase

Question 40

pathways of aerobic metabolism

Answer 40

glucose secreted by liver into blood; muscle glycolysis increases (ATP production increases), gluconeogenesis increases (when ATP demand greater than supply), fatty acids increase (more available for B-oxidation)

Question 41

what protein channels are required for cation balance in aerobic metabolism

Answer 41

Ca2+ATPase and Na+K+ATPase

Question 42

aerobic pathways diagram

Answer 42

diagram from metabolism 9

Question 43

when is anaerobic respiration required

Answer 43

when ATP demand is greater than oxidative phosphorylation supply and transport cannot keep up with glucose demand

Question 44

pathways of anaerobic metabolism

Answer 44

muscle glycogen breakdown increases; glycolysis rate increases fo pyruvate accumulates and is stored as lactate in muscles; liver uses lactate to form pyruvate via LDH (gluconeogenesis) to be converted to glucose, preventing acidosis

Question 45

anaerobic pathway diagram

Answer 45

diagram from metabolism 9

Question 46

3 fates of pyruvate

Answer 46

alcoholic fermentation, lactate, generation of acetyl CoA

Question 47

alcoholic fermentation

Answer 47

ethanal → ethanol by decarboxylases; produces NAD+ so glycolysis can continue

Question 48

lactate production

Answer 48

pyruvate ⇌ lactate via lactate dehydrogenase (LDH), produces NAD+ so glycolysis can continue

Question 49

creatine phosphate metabolism

Answer 49

creatine phosphate ⇌ creatine + ATP by creatine kinase

Question 50

high levels of LDH or creatine kinase in plasma

Answer 50

tissue and muscle trauma, myocardial infarction