Lec 13 and 14: Cellular Respiration I and II

Question 1

explain the diffference between metabolism, catabolism and anabolism

Answer 1

metabolism: all the chemical reactions in the body
catabolism: beaking down complex molecules

Anabolism: (endergonic) building of complex molecules

metabolism is the balance between the energy inputs and outputs of anabolism and catabolism

Question 2

in what type of reactions is ATP used and made?

Answer 2

ATP is used in anabolic reactions

can be made in catabolic reactions

Question 3

how is catabolism and anabolism coupled by ATP?

Answer 3

• catabolic reactions transfer energy from moleciles to ATP (releasing heat)
• these are simple molecules such as glucose, amino acids, glycerol and fatty acids.
• anabolic reactions transfer energy from ATP to complex molecules (releasing heat)
• these are molecules such as starch, proteins and lipids

cycle starts again

Question 4

In starvation catabolism drops, explain what happens to the rate of anabolic processes

Answer 4

drop in catabolism means a drop in the break down of complex molecules

that provide energy for the production of ATP

therefore resulting in less amount of energy from ATP being provided

for the building of complex molecules (anabolic reactions)

rate of anabolic processes lowers

Question 5

In liver cells (metabolises poisons) does anabolism or catabolism predominate?

Answer 5

catabolism

Question 6

In a pancreatic cell producing digestive enzymes does anabolism or catabolism predominate

Answer 6

anabolism

Question 7

What are the bodies main ways of storing energy

Answer 7

stores energy in nutrients

molecules such as glycogen (in liver) and triglycerides (in adipose tissue) store energy

Question 8

why is ATP a good energy source for cells?

Answer 8

• contains high energy phospahte bond
• which can be released easily and quickly

Question 9

what is oxidation

Answer 9

removal of electrons or hydrogen

/

addition of oxygen

decreasing potential energy

Question 10

does oxidation or reduction take place in dehydrogenation reactions?

Answer 10

oxidation

Question 11

what is NAD?

give the eqaution for the reduction of NAD

Answer 11

nicotinamide adenine dinucleotide

a derivative of the B vitamin niacin

Question 12

what is FAD?

give the eqaution for the reduction of FAD

Answer 12

flavin adenine dinucleotide

derivative of the B vitamin riboflavin

Question 13

how does phosphorylation (addition of P group) affect potential energy?

Answer 13

increases a molecules potential energy

Question 14

what is subtrate level phosphorylation?

where does it occur

Answer 14

Transferring high-energy phosphate group from an intermediate directly to ADP

(occurs in the cytosol)

Question 15

what is oxidative phosphorlyation?

where does it occur?

Answer 15

Remove electrons and pass them through electron transport chain to oxygen

occurs in the inner mitochondrial membrane

Question 16

where is the only place Photophosphorylation takes place?

Answer 16

Only in chlorophyll-containing plant cells

Question 17

what type of cell converts fructose to glucose

Answer 17

intestinal epithelial cells

Question 18

what type of cells convert fructose and galactose to glucose?

Answer 18

hepatocytes

Question 19

how does glucose move into the cells of the Gi tract?

Answer 19

by co transport

Question 20

what is insulin and what is its function?

Answer 20

Insulin is a hormone

made by the pancreas

that allows your body to use glucose from carbohydrates in the food

for energy or to store glucose for future use.

Insulin helps keeps your blood sugar level from getting too high (hyperglycemia) or too low (hypoglycemia).

Question 21

what happens in glycolysis?

steps 1-5

Answer 21

• Splits 6-carbon glucose into two 3-carbon molecules of pyruvic acid
• Consumes 2 ATP but generates 4

1. Glucose –> Glucose 6-phosphate

(hexokinase, uses ATP and produces ADP + H+)

2. Gluocse 6-phosphate –> Fructose 6-phosphate

(isomerase)

3. Fructose 6-phosphate –> Fructose 1,6-biphosphate

(phosphofructase, uses ATP ad produces ADP + H+)

4a. Fructose 1,6-biphosphate –> Glyceraldehyde 3-phosphate

(aldolase)

4b. Fructose 1,6-biphosphate –> dihydroxyacetone phosphate

(aldolase)

5. Glyceraldehyde 3-phosphate –> dihydroxy acetone phosphate

(triosephosphate isomerase)

Question 22

what is the key regulator of glycolysis?

Answer 22

Phosphofructokinase

PFK

Question 23

when are phosofructokinase levels high?

Answer 23

when ADP levels are high

Question 24

how do ADP levels affect glycolysis

Answer 24

high ADP levels

indicate high phoshofructokinase acitivity

so high rate of glycolysis

/

low ADP levels

glucose is shunted away from glycolysis

to the glycogen storage pathway

Question 25

what is Tarui disease?

Answer 25

where there is a lack of PFK results in exercise intolerance, with pain, cramps and, occasionally, myoglobinuria (acute muscle breakdown leading to rust-colored urine). A partial deficiency of phosphofructokinase in the red blood cells results in the breakdown of those cells and an increase in blood levels of bilirubin (a chemical found in red blood cells)

Question 26

what happens in glycolysis? steps 6-10

Answer 26

6. Glyceraldehyde 3-phosphate --\> 1,3-biophosphoglycerate (glyceraldehyde phosphate dehydrogenase uses NAD and HPO4^2- to make NADH + H+) 7. 1,3-biphoshpoglycerate --\> 3-phosphoglycerate (phosphoglycerate kinase, uses ADP to make ATP) 8. 3-phosphoglycerate --\> 2-phosphoglycerate (phosphoglycerate muatase) 9. 2-phosphoglycerate --\> phosphoenolpyruvate (enolase) 10. phosphoenlpyruvate --\> pyruvate (pyruvate kinase, uses ADP + H+ to make ATP)

Question 27

In glycolysis; how many NADH + H+ molecules are made how many ATP molecules are used and generated

Answer 27

6 NADH + H+ molecules use 2 ATP molecules and generate 4

Question 28

what are the NADH + H+ molecules used to make? and in which cells?

Answer 28

* Most cells use these to generate 4 ATPs in the electron transport chain * Hepatocytes and cardiac muscle fibres generate 6 ATPs from them

Question 29

where is the location of glycolysis?

Answer 29

cystosol

Question 30

what is the fate of pyruvic acid depending on whether anaerobic or aerobic respiration takes place?

Answer 30

anaerobic: reduced to 2 lactic acid molecules 2 molecules are reduced by 2 H atoms from NADH lactic acid enters the blood and is converted back to pyruvate by hepatocytes aerobic: converted to acetylcoenzyme A

Question 31

why is the reduction of pyruvate in anaerobic respiration important to glycolysis?

Answer 31

when 2 pyruvates are reduced by 2 NADH it regenerates 2NAD+ which are required in step 6: 6. Glyceraldehyde 3-phosphate --\> 1,3-biophosphoglycerate (glyceraldehyde phosphate dehydrogenase uses NAD and HPO42- to make NADH + H+ without the NAD glycolysis can not continue

Question 32

what is the importance of converting pyruvate to acetyl coenzyme A in aeoribic respiration

Answer 32

* molecule links glycolysis (cytoplasm) to Krebs (matrix of mitochondria) * RBC’s lack mitochondria so can only perform glycolysis

Question 33

what enzyme converts pyruvate to acetyl coenzyme A?

Answer 33

pyruvate dehydrogenase

Question 34

what is the net gain of ATP, NADH and Acetyl coenzyme A molecules in glycolysis and krebs cycle?

Answer 34

Net gain from glycolysis and link reaction * 2 ATP molecules * 4 NADH molecules * 2 Acetyl coenzyme A molecules

Question 35

what is Pyruvate dehydrogenase deficiency?

Answer 35

a sex linked disease Pyruvate dehydrogenase deficiency

Question 36

where does the krebs reaction take place?

Answer 36

in the matrix of the mitochondria

Question 37

\*NOTE\* Krebs cycle overview

Answer 37

start of with: 3 NADH 1 FADH2 Contain the energy originally stored in glucose Later each NADH makes 3 ATP molecules FADH2 makes 2 ATP molecules 1 ATP made by substrate level phosphorylation

Question 38

how many ATP molecules are made in total in the krebs cycle?

Answer 38

12 ATP (24 per glucose molecule)

Question 39

what are the steps in the krebs cycle?

Answer 39

1. Entry of acetly group to create citrate & regeneration of CoA 2. Isomerisation to isocitric acid 3. Oxidative decarboxylation. Remove CO2 & formation of NADH & alpha ketoglutarate 4. Oxidative decarboxylation and addition of CoA to form succinyl-CoA & NADH 5. Substrate level phosporylation. CoA is displaced for a phosphate group, which is transferred to GDP and donated to ATP. Forms succinate 6. Dehydration. Succiante is oxidised furmarate by FADH2 formation 7. Hydration. Furmarate is converted to malate by addition of water 8. Dehydrogenation to oxaloacetate & formation of NADH

Question 40

how many CO2 molecules does krebs produce from each glucose molecule?

Answer 40

4

Question 41

1Which enzyme in Krebs allows for substrate level phosphorylation?

Answer 41

succinyle co-A synthetase

Question 42

why do you breathe out more CO2 after excersise?

Answer 42

more turns of krebs

Question 43

which three enzymes in krebs reduce NAD?

Answer 43

- isocitrate - ketogluterate - malate dehydrogenase

Question 44

what is the electron transport chain?

Answer 44

a series of electron carries in the inner mitochondrial membrane

Question 45

what is the final electron acceptor?

Answer 45

oxygen

Question 46

what happens in the electron transport chain?

Answer 46

1. Energy from NADH + H+ passes along the electron transport chain (via REDOX) & is used to pump the proton pump 2. A high concentration of H+ accumulates between the membranes 3. ATP synthesis occurs as the H+ ions flow back into the matrix through the H+ channels

Question 47

how many molecules of ATP are produced in the electron transport chain?

Answer 47

32 or 34 per glucose molecule

Question 48

how many molecules of ATP are made from NADH + H+ and FADH₂

Answer 48

10 molecules of NADH + H+ produce 28 or 30 mols of ATP 2 molecules of FADH₂ produce 2 mols of ATP

Question 49

\*NOTE\* for NADH in krebs cycle

Answer 49

* NADH made in glycolysis cannot enter the mitochondria. * They donate electrons to malate or glycerol phosphate shuttle

Question 50

which organs use the malate shuttle and how many ATP molecules are produced as a result?

Answer 50

•Liver, kidneys & the heart= 3ATP molecules result

Question 51

how many ATP molecules are made as a result of the glycerol phosphate shuttle?

Answer 51

2 ATPs

Question 52

how many molecules of ATP are made in substrate level phosphorlyation in glycolysis and krebs cycle?

Answer 52

substrate level phosphorylation in glycolysis = 2 ATP substrate level phosphorylation in the Krebs cycle = 2ATP

Question 53

\*NOTE\* ATP yield per glucose molecule

Answer 53

Question 54

what is the role of NAD dehydrogenase in the krebs cycle?

Answer 54

reduces NAD/FAD by oxidising a substrate

Question 55

what is chemiosmosis?

Answer 55

the use of energy in a chemical gradien to generate ATP by the flow of hydrogen ions through ATP synthase

Question 56

how is a H+ gradient built up in the mitochondria? that is the purpose of this?

Answer 56

H+ ions from the matris are pumped into the intermembrane space the inner mitcohondrial membrane is impermeable to H+ ions so a gradient forms H+ ions move down their concentration gradient, into the matrix using protein channels that are associated with the enzyme ATP synthase ATP synthase phosphorylates 1 ADP for each H+ ion therefore protons are a direct energy source for producing ATP

Question 57

why can a liver cell make more ATP per glucose molecule than a lung cell?

Answer 57

liver cells use the malate shuttle to recieve electrons from NAD this results in the production of 3 ATP molecules where as a lung cell would use the glycerol phosphate shuttle resulting in the production of 2 ATP molecules

Question 58

what stimulates glycogenesis?

Answer 58

insulin in hepatocytes and muscle cells

Question 59

what is the role of phosphoglucomutase?

Answer 59

interconverts Glucose 6-phosphate to Glucose 1-phosphate

Question 60

under what metabolic conditions will glycogensis occur?

Answer 60

in high levels of ATP and glucose

Question 61

what hormone stimulates glycogenesis?

Answer 61

insulin

Question 62

how can the hormone glucagon help keep blood sugars up?

Answer 62

- pancreas releases glucagon when blood glucose levels are too low - glucagon stimulates glycogenolysis which produces glucose from glycogen with the use of phosporylation

Question 63

which two hormones activate glycogen phosphorylase?

Answer 63

glucagon and adrenaline