Ch. 9: Metabolism Flashcards

1
Q

What is the most common source of fuel in cells?

A

Glucose

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2
Q

What are the 5 principles of metabolic pathways?

A
  1. Complex transformations occur in a series of separate reactions
  2. Each reaction is catalyzed by a specific enzyme
  3. Many metabolic pathways are similar in all organisms
  4. In eukaryotes, metabolic pathways are compartmentalized in specific organelles
  5. Key enzymes in each pathway can be inhibited or activated to alter the rate of the pathway
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3
Q

3 catabolic processes that harvest energy from glucose

A
  1. Glycolysis
  2. Cellular respiration
  3. Fermentation
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4
Q

In glycolysis, 1 glucose produces:

A

2 ATP & 2 pyruvate

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5
Q

After glycolysis and the Krebs Cycle (Citric Acid Cycle), how much ATP, NADH, CO2, ans FADH2 do we have?

A

6 CO2
8 NADH
2 FADH2
4 ATP

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6
Q

Where does the Krebs (citric acid) cycle take place?

A

The mitochondrial matrix (inner core of the mitochondria)

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7
Q

What is oxidative phosphorylation?

A

The electron transport chain and chemiosmosis

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8
Q

Where does oxidative phosphorylation take place?

A

In/on the inner membrane of the mitochondria

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9
Q

How does oxidative phosphorylation form ATP?

A

It separates protons from FADH2 and NADH, using the energy of the proton gradient to attach P to ADP, thus producing ATP.

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10
Q

How much total ATP can you get from one glucose using aerobic respiration?

A

30-32 ATP

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11
Q

When no oxygen is present, what process do cells follow?

A

Fermentation (lactic acid or alcohol)

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12
Q

In lactic acid fermentation, what does pyruvate do?

A

Pyruvate is the electron acceptor, and lactate is the product.

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13
Q

What is the lactate threshold?

A

Point at which production exceeds removal in blood

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14
Q

In alcoholic fermentation, what does pyruvate do?

A

Pyruvate gets converted to ethanol, releasing CO2 along the way.

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15
Q

As far as catabolic interconversions go, what do polysaccharides break down into and what stage of metabolism do they enter?

A

Glucose, entering glycolysis

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16
Q

As far as catabolic interconversions go, what do lipids break down into and what stage of metabolism do they enter?

A

Glycerol for glycolysis and fatty acids (which turn into acetyl coA) for the citric acid cycle

17
Q

As far as catabolic interconversions go, what do proteins break down into and what stage of metabolism do they enter?

A

Amino acids, entering either glycolysis or the citric acid cycle (but not the best use of proteins, as we know)

18
Q

What is gluconeogenesis?

A

Glucose formed from citric acid cycle and glycolysis intermediates
(Anabolic reactions are just reverse catabolic reactions)
(i.e. acetyl coA can be used to make fatty acids)

19
Q

Are catabolic reactions reversible?

A

Yes, most of them are

20
Q

If 100 molecules of glucose are fermented, what is the approximate net yield of ATP molecules?

A

200 ATP molecules

21
Q

Is glycolysis aerobic or anaerobic?

A

Anaerobic

22
Q

Is cellular respiration aerobic or anaerobic?

A

Aerobic (though some microorganisms have developed anaerobic respiration, which uses small molecules or ions as electron acceptors instead of O2)

23
Q

Is fermentation aerobic or anaerobic?

A

Anaerobic

24
Q

In the redox equation below, which is reduced and which is oxidized? Identify the oxidizing and reducing agents.

Na + Cl —> Na+ + Cl- (or NaCl)

A

Na is oxidized, making it the reducing agent, because it gives away its electron.
Cl is reduced (see the reduction in the charge), making it the oxidizing agent, because it gained an electron.

25
Q

True or false: the more oxidized a molecule is, the more energy it stores.

A

False. The more reduced a molecule is, the more energy it stores.

26
Q

In a prokaryote, what are the locations of these metabolic processes: glycolysis, pyruvate oxidation, citric acid cycle, respiratory chain, and fermentation?

A

Glycolysis, fermentation, and the citric acid cycle take place in the cytoplasm.
Pyruvate oxidation and the respiratory chain take place on the cell membrane.

27
Q

In a eukaryote, what are the locations of these metabolic processes: glycolysis, pyruvate oxidation, citric acid cycle, respiratory chain, and fermentation?

A

Glycolysis and fermentation take place in the cytoplasm.
The citric acid cycle and pyruvate oxidation are in the mitochondrial matrix.
The respiratory chain takes place on the inner mitochondrial membrane.

28
Q

What are the 2 steps in oxidative phosphorylation?

A

(1) Electron transport chain and (2) Chemiosmosis

29
Q

Why is oxidative phosphorylation so complicated with so many steps?

A

Because a one-step process would release too much energy to be harvested. It would be like setting off dynamite in the cell.

30
Q

Of the 4 integral proteins in the electron transport chain, how many are transmembrane?

A

3 (I, III, & IV)

31
Q

What is the order that electrons go through in the electron transport chain?

A

I, II, Q, III, Cytochrome C, IV

32
Q

What is the proton-motive force?

A

A force generated by the difference in charge and concentration gradients of protons and electrons across the membrane.

33
Q

What are gradients good for?

A

Potential energy

34
Q

True or false: cytochrome c harnesses energy for ATP as the H+ diffuses back across the membrane (through ATP synthase).

A

False. Chemiosmosis does this, not cytochrome c.

35
Q

What mechanisms regulate the rate of each step in a biochemical pathway?

A
  • Changing the amount of active enzyme
  • Changing enzyme activity by covalent modifications
  • Feedback inhibition
  • Substrate availability