Metabolism Physiology

Question 1

What enzyme channel produces ATP through oxidative phosphorylation?

Answer 1

ATP Synthetase

Question 2

What flow of ions is required by ATP synthetase for oxidative phosphorylation?

Answer 2

H+

Question 3

Where in the cell does oxidative phosphorylation take place?

Answer 3

Inner mitochondrial membrane

Question 4

Where does the supply of H+ ions for oxidative phosphorylation come from?

Answer 4

Oxidation of NADH or FADH2 - releases H+ and free electrons

Question 5

How is hydrogen pumped out of the mitochondrial matrix in order to create a H+ gradient for flow through the ATP synthetase channel?

Answer 5

Electron transport chain

Question 6

What process creates NADH and FADH2 that are required for producing the H+ ions for oxidative phosphorylation?

Answer 6

Krebs cycle

Question 7

In the krebs cycle, what combines to form citric acid?

Answer 7

Acetyl CoA + Oxaloacetate –> Citric acid

Question 8

What is produced from the Krebs cycle?

Answer 8

2 x Co2
1 x ATP
3 x NADH
1 x FADH2

Question 9

Is the krebs cycle aerobic or anaerobic?

Answer 9

Aerobic - uses O2

Question 10

Where does the krebs cycle take place?

Answer 10

Mitochondrial matrix

Question 11

Which food group substrates can create Acetyl CoA for the Krebs cycle

Answer 11

Carbohydrates –> Glucose
Protein –> Amino acids
Fats –> Glycerol and free fatty acids (FFA)

All except FFA converted to pyruvate then to acetyl coA
FFA converted directly into acetyl coA

Question 12

What is the name for the conversion of glucose to pyruvate?

Answer 12

Glycolysis

Question 13

What is the initial step in glycolysis which requires ATP?

Answer 13

Glucose –> G-6-P

Question 14

During the series of enzymatic reactions of glycolysis, from 1 glucose molecules, how many molecules of pyruvate, ATP and NADH are formed?

Answer 14

2 pyruvate
2 ATP net (4 ATP produced in total but requires 2)
2 NADH

Question 15

How is glycerol (from fat) converted to pyruvate?

Answer 15

Enters glycolysis pathway

Question 16

How do amino acids gain access to the krebs cycle?

Answer 16

1) Conversion to pyruvate then to acetyl Coa
2) Direct access into cycle

Question 17

Where does glycolysis take place?

Answer 17

Cytoplasm

Question 18

What process converts free fatty acids into acetyl coA?

Answer 18

B-oxidation

Question 19

Where does B-oxidation take place?

Answer 19

In the mitochondria

Question 20

Which by-product of B-oxidation can gain access to the krebs cycle directly?

Answer 20

ketoacid

Question 21

How many ATP are released from one molecule of glucose if fully metabolised via glycolysis then krebs cycle?

Answer 21

38 ATP

Question 22

How many ATP are required for glycolysis?

Answer 22

2 x ATP

Question 23

During anaerobic metabolism what happens to pyruvate?

Answer 23

Converted to lactate

Question 24

During anaerobic metabolism, how many ATP are released for one glucose molevule?

Answer 24

4 ATP - net 2

Question 25

What happens to lactate once aerobic conditions are restored? What is the name of this?

Answer 25

Transported to liver and converted to glucose Cori cycle

Question 26

What molecules gain access to the krebs cycle?

Answer 26

Acetyl CoA Lactate Amino acids Ketoacids

Question 27

What are the 3 end products of full aerobic metabolism of glucose?

Answer 27

ATP, H2O and Co2

Question 28

During starvation, how long before glycogen stores are exhausted?

Answer 28

24 hours

Question 29

How are basal blood glucose levels maintained within first 24 hours of starvation?

Answer 29

Glycogenolysis

Question 30

After the first 24 hours of starvation once glycogen levels are exhausted, how does the body try maintain basal blood glucose levels?

Answer 30

Amino acids and glycerol converted to pyruvate and converted back to glucose

Question 31

In the prolonged starvation period, how is the krebs cycle driven?

Answer 31

Via ketoacids (by product of FFA metabolism)

Question 32

Despite starvation, which 3 organs/cells still require glucose as their primary energy source?

Answer 32

1) Erythrocytes 2) Renal medulla 3) CNS (50% requires glucose, 50% concers to ketoacid metabolism)

Question 33

Where does glycogenolysis take place?

Answer 33

Liver and muscles

Question 34

Where does glycogenesis take place?

Answer 34

Liver and muscles

Question 35

Where does gluconeogenesis take place?

Answer 35

Liver and kidneys

Question 36

Which cells secrete insulin?

Answer 36

Pancreatic beta cells - Islets of langerhan

Question 37

What receptor does insulin act via?

Answer 37

tyrosin kinase receptors

Question 38

How does insulin binding to tyrosine kinase receptors cause an increase in glucose uptake?

Answer 38

Translocation of glucose transporters to cell membrane (GLUT 4 transporters)

Question 39

Which cells secrete glucagon?

Answer 39

Pancreatic alpha cells

Question 40

What receptor does glucagon act via? and where are these found?

Answer 40

G-protein linked receptors in the liver

Question 41

Describe the structure of the insulin hormone?

Answer 41

51 amino acids in 2 peptide chains linked by di-sulphide bridges

Question 42

Describe the structure of the glucagon hormone?

Answer 42

29 amino acids in a single chain polypeptide

Question 43

Compare alpha 2 and beta-adrergic stimulation with regards to insulin/glucagon secretion?

Answer 43

Alpha 2 - decreases insulin Beta - increases glucagon secretion Both lead to increased blood sugar

Question 44

What cells release somatostatin?

Answer 44

Pancreatic delta cells - islets of langerhan Hypothalamus

Question 45

What are the actions of somatostatin?

Answer 45

Reduces gut motility/sercretion Inhibits release of insulin and flucagon

Question 46

Is insulin anabolic or catabolic?

Answer 46

Anabolic (build up) Synthesis of glycogen, protein and fat

Question 47

Compare insulin and growth hormone effects on fat metabolism?

Answer 47

insulin - fat synthesis growth hormone - fat breakdown

Question 48

What does hypothermia do to glucose levels?

Answer 48

Increases