(LE2) Carbohydrate Catabolism Flashcards

1
Q

Describe carbohydrate catabolism

A

Glucose is oxidized into 6CO2
- e- are transferred from glucose to electron carriers (NAD+ or FADH). Taken to electron transport chain

Oxygen is reduced into H2O

Energy is released

NADH/FADH2 is oxidized back into its original form NAD+/FADH

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2
Q

What are the three types of carbohydrate catabolism?

A
  1. Aerobic respiration
  2. Anaerobic respiration
  3. Fermentation
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3
Q

Describe aerobic respiration

A
  • Utilizes ETC
  • Fastest
  • the final e- acceptor is an inorganic molecule (O2)
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4
Q

Describe anaerobic respiration

A
  • Utilizes ETC
  • final e- acceptor is a different inorganic molecule (NO3-, SO4^2-, CO3^2-)
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5
Q

Describe fermentation

A
  • slowest
  • final e- acceptor is an organic molecule (e.g. pyruvate) (incomplete glucose oxidation)
  • no O2 is used
  • glycolysis only
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6
Q

What is the ATP yield during aerobic respiration for prokaryotes? Where does it occur?

A
  • 38 ATP/glucose
  • occurs in cytoplasm and across the plasma membrane
    phospholipid bilayer needed for ETC
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7
Q

What is the ATP yield for aerobic respiration for eukaryotes? Where does it occur?

A
  • 36 ATP/glucose
  • occurs in cytoplasm and mitochondria
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8
Q

What are the steps of aerobic respiration?

A
  1. Glycolysis
  2. Kreb’s (citric) cycle
  3. Electron transport chain
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9
Q

What is the main purpose of Glycolysis and the Kreb’s cycle?

A

to make electron carriers to power the ETC

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10
Q

What organisms can perform glycolysis?

A

All organisms (aerobic and anaerobic)
Does not need O2 to occur
Occurs in respiration and fermentation

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11
Q

What is your net yield in glycolysis?

A

2 ATP
2 NADH
2 Pyruvate (3C)

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12
Q

What 10 steps are occurring in glycolysis? What are there yields?

A

Preparatory steps: Glucose (6C) -> 2 (3C) molecules
- requires 2 ATP
Energy yielding steps: 2 (3C) molecules -> 2 Pyruvate
- generates 2 NADH
- generates 4 ATP

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13
Q

What is happening in this image?

A

Glyceraldehyde-3-phosphate is oxidized and phosphorylated into1,3-Diphosphoglyceric acid

NAD is reduced into NADH

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14
Q

What is happening in this image?

A

1,3-Diphosphoglyceric acid is dephosphorylated into 3-phosphoglyceric acid
ADP is phosphorylated into ATP
ATP via SLP

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15
Q

What is happening in this image?

A

Phosphoenolpyruvic acid is dephosphorylated into Pyruvic acid
ADP is phosphorylated into ATP
ATP via SLP

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16
Q

Do fermenters perform the Kreb’s cycle?

A

No

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17
Q

Where does Kreb’s cycle occur for prokaryotes? Eukaryotes?

A

P: cytoplasm
E: mitochondrial matrix

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18
Q

What main steps occur during the second step of aerobic respiration?

A
  1. Pyruvate -> Acetyl CoA
  2. Kreb’s cycle
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19
Q

What is the formula for pyruvate to Acetyl CoA?

A

Pyuravte + NAD + CoA -> Acetyl CoA + CO2 + NADH

  • Pyruvate is oxidized & decarboxylated to Acetyl-CoA
  • NAD reduced to NADH
20
Q

What is the yield per glucose in Pyruvate oxidation to Acetyl CoA?

A

2 CO2
2 Acetyl CoA
2NADH

21
Q

What is happening in step one and two of the image?

A
  1. Pyruvate is decarboxylated
  2. Pyruvate is oxidized. NAD+ reduced to NADH
22
Q

What step does complete oxidation of glucose occur?

A

Kreb’s cycle

22
Q

Where is pyruvate oxidized into Acetyl CoA in eukaryotes?

A

on membrane

23
Q

What is the net yield for each Acetyl CoA in the Kreb’s cycle?

A

2 CO2
3 NADH
1 FADH2
1 ATP

24
Q

What is the net yield per glucose in the Kreb’s cycle?

A

4 CO2
6 NADH
2 FADH2
2 ATP

25
Q

Explain what is happening in step 3

A

Isocitric acid is oxidized and decarboxylated into alpha-Ketoglutaric acid
NAD+ is reduced to NADH

26
Q

Explain what is happening in step 5

A

ADP is phosphorylated into ATP
ATP via substrate-level phosphorylation

27
Q

What step of aerobic respiration is occurring in this picture? What is the purpose?

A

Electron transport chain
- create ATP via oxidative phosphorylation (series of redox)

28
Q

Where does ETC happen for prokaryotes? Eukaryotes?

A

P: periplasmic space and intracellular membrane
E: across the inner mitochondrial membrane (intramembranous space)

29
Q

What do e- carriers do in the ETC?

A

pass e- to membrane complexes
- pumps H+ across membrane
- creates H+ gradient

final e- carrier is O2 (O2-> H2O)

30
Q

What is the net yield of ATP for e- carriers in the ETC?

A

3 ATP/NADH
2 ATP/FADH2

31
Q

What is chemiosmosis?

A

the use of energy in a H+ gradient to drive cellular work

32
Q

What structure is shown here? How does it operate?

A

ATP synthase
- uses energy released by H+ movement to phosphorylate ADP

33
Q

How many total electron carriers are made during aerobic respiration? What are their net yields? What is the total yield per glucose in prokaryotes? Eukaryotes?

A

10 NADH (3 ATP/NADH) = 30 ATP
2 FADH2 (2 ATP/FADH2) = 4 ATP

P: 38 ATP/Glucose
E: 36 ATP/Glucose

34
Q

Why do eukaryotes only generate 36 ATP compared to prokaryotes?

A

2 ATP are needed to transport the 2 NADH generated from glycolysis into the mitochondria (ETC)

35
Q

Calorie content of each macronutrient?

A

Carb: 4 kcal
Fat: 9 kcal
Protein: 4 kcal

36
Q

How are proteins converted into ATP?

A

Broken down to amino acids
Amino acid catabolism lets it enter Kreb’s cycle and ETC
- Most skip glycolysis

37
Q

How are fats converted into ATP?

A
  • Glycerol goes to glycolysis
  • Fatty acids undergo Beta-oxidation, then Kreb’s cycle and ETC
37
Q

What is fermentation’s net ATP yield?

A

2 ATP/Glucose

38
Q

What type of fermentation is this? Explain the steps after typical glycolysis. What is the final e- carrier?

A

Alcohol fermentation
- pyruvate is decarboxylated into acetaldehyde
- acetaldehyde is reduced into ethanol
- NADH is oxidized into NAD+
Acetaldehyde is the final e- carrier

38
Q

What type of fermentation is this? Explain the steps after typical glycolysis. What is the final e- carrier?

A

Lactic acid fermentation
- pyruvate is reduced into lactate
- NADH is oxidized into NAD+ to restart glycolysis
Pyruvate is the final e- carrier

39
Q

What steps are performed in anaerobic respiration?

A
  1. Glycolysis
  2. modified Kreb’s cycle
  3. ETC
40
Q

What is the energy yield of anaerobic respiration?

A

Variable: 2 < x < 38 ATP

41
Q

Nitrate reduction

A

Nitrate cycle in soils
- members of Bacillus and Pseudomonas
- NO3- (nitrate) -> NO2- (nitrite) usable form for plants

42
Q

Sulfate Reduction

A

(wetlands, swamps)
- SO4^2- (sulfate) -> H2S (hydrogen sulfide gas)

43
Q

Carbonate Reduction

A

Sewage Treatment
- CO3^2- (carbonate) -> (methane)