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Biology 189 > L12: Cellular Respiration & Fermentation Processes > Flashcards

L12: Cellular Respiration & Fermentation Processes Flashcards

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1
Q

What is the overall role of cellular respiration? What do cells do with all of the ATP they make via cellular respiration?

A

“recharge” ATP - exergonic
ATP powers most cellular work

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2
Q

Which cellular organelle plays a prominent role in cellular respiration?

A

mitochondria

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3
Q

From an ecological perspective, how is cellular respiration coupled with photosynthesis?

A

it’s reactants and products are opposite of each other

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4
Q

Which biota possess mitochondria? Which biota posses chloroplasts?

A

animals - mitochondria
plants - mitochondria & chloroplasts

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5
Q

Which two factors determines how most biota recharge their ATP batteries?

A

electron transfer system/chain (ETC) & final electron acceptor (FEA)

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6
Q

Which types of cells possess mitochondria? Mitochondrial-bearing cells respire. What does that mean?

A

eukaryotic cells with mitochondria respire (take in oxygen and release CO2)

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7
Q

What is a final electron acceptor (FEA)(you will have to finish the lesson to answer this one)?

A

last on the etc that takes the leftover electrons to combine protons with oxygen to form H2O

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8
Q

Which four biochemical pathways do humans and other mitochondria-bearing biota use to meet their energetic demands? Why are some of these pathways referred to as cellular respiration?

A

Cytosolic processes: (1) glycolysis (not technically respiration).

Mitochondrial processes (considered cellular respiration bc requires oxygen): (2) transition rxn,(3) Kreb’s cycle
and (4) oxidative phosphorylation (ETC and chemiosmosis).

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9
Q

Which pathways occur in the cytosol and which occur in mitochondria? Can you list these pathways in the sequence in which they occur within cells?

A

Cytosolic processes: (1) glycolysis (not technically respiration).

Mitochondrial processes (considered cellular respiration bc requires oxygen): (2) transition rxn,(3) Kreb’s cycle
and (4) oxidative phosphorylation (ETC and chemiosmosis).

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10
Q

I made several modifications to figure summarizing aerobic cellular respiration. You should be able to recognize these modifications because questions will be derived on the modifications (e.g., transition rxn, Kreb’s cycle, additional reduced coenzymes, and oxidized coenzymes).

A

ok

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11
Q

What is a redox reaction?

A

Metabolism strips electrons (e– ) from substrates and transfer them via H atoms during oxidation-reduction or redox rxns.

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12
Q

What does it mean when we say that a molecule has been oxidized? What does it mean when we say that a molecule has been reduced?

A

oxidized - lost 2e-
reduced - gained 2e- (have more energy than before)

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13
Q

Which two coenzymes (aka energy carriers) are routinely reduced by electrons stripped from metabolic substrates via oxidation? How do we symbolize the oxidized and reduced versions of the two coenzymes associated with metabolism?

A

One e– per H atom is transferred to coenzymes NAD+
and FAD. These energy carriers take 2 e– each to the ETC.

NAD+ to NADH + H+

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14
Q

I prepared a table classifying many biochemical pathways that you will need to learn. What is a NAD+ regenerating pathway?

A

ATP generating pathways (ETC)
Aerobic: O2 is the final electron acceptor, human
Anaerobic - O2 is NOT FEA; ions or others are, prokaryote

Pthaways that DONT generate ATP (no RTC)
Alcoholic Fermentation- makes CO2 and ethanol, yeast (in low O2)
Homolactic Fermentation - makes lactic/lactate, humans (in low CO2)

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15
Q

What is the sequence of biochemical pathways that your cells go through when O2 is available?

A
  • glycolysis (with or without)
  • transition
  • krebs cycle
  • oxidative phosphorylation
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16
Q

Which of these pathways produce substrate-level ATP? How much substrate-level ATP do they produce?

A

glycolysis - 2 atp
krebs cycle - 2 atp
oxidative phosphorylation - 26-28 atp

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17
Q

Which of these pathways reduce coenzymes? How many coenzymes are reduced during each pathway?

A

glycolysis - 2 NAD+
transition rxn - 2 NAD+
Krebs cycle - 6 NAD+ & 2 FAD

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18
Q

Where do coenzymes take the electrons they received when they were reduced?

A

ETC

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19
Q

Where are the reduced coenzymes oxidized? Where must the oxidized coenzymes go after they have been stripped of electrons?

A

shuttled into the mitochondria to participate in an ETC

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20
Q

What is the substrate of glycolysis? What are the products of glycolysis? (glycolysis)

A

substrate (inputs):
- C6H12O6 (glucose)

products (outputs):
- 2 (pyruvate + protons)
2 (C3H3O3 + H+)
- 2 atp
- 2 NAD+ reduced

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21
Q

During glycolysis, how many ATP are invested, how many total ATP are produced, and what is the net number of ATP produced? (glycolysis)

A

invested - 2
produced - 4
net # - 2

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22
Q

Which coenzyme is reduced during glycolysis? How many of this coenzyme is reduced? Where did the electrons come from to reduce the coenzymes? (glycolysis)

A

2 NAD+ reduced into 2 NAD2e-

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23
Q

Where do the products and reduced coenzymes go when O2 is plentiful? (glycolysis)

A

products go into the mitochondria for transition rxn and reduced coenzymes go into th mitochondria to participate in the ETC

24
Q

Where does glycolysis occur within a cell? (glycolysis)

A

cytosol

25
Q

How many enzyme-catalyzed chemical reactions are involved in glycolysis? (glycolysis)

A

10

26
Q

Is O2 used during glycolysis? (glycolysis)

A

it can occur with or without oxygen present

27
Q

What will happen to glycolysis if a cell runs out of NAD+? How does a cell get more NAD+ when [O2] is plentiful? (glycolysis)

A

homolactic fermentation

28
Q

Which pathway must a cell carry out to regenerate when [O2] is deficient? (glycolysis)

A

homolactic fermentation to oxidize coenzyme

29
Q

What is the substrate of the transition rxn? What are the products of transition rxn? (transition)

A

substrate:
- 2 pyruvate (3-Carbon)

products:
- 2 acetyl-coA (2-Carbon)
- 2 CO2 (exhaled, some forms carbonic acid (H2CO3) in the blood, and some imbibes with NH3 to form urea)
- 2 NAD+ reduced

30
Q

How many ATP are produced? (transition)

A

0

31
Q

Which coenzyme is reduced during transition rxn? How many of this coenzyme is reduced? Where did the electrons come from to reduce the coenzymes? (transition)

A

2 NAD+ into 2 NAD2e- H+

came from the 2 pyruvate

32
Q

Where do the products and reduced coenzymes go when O2 is plentiful? How does this change when the cell is O2 is deficient? (transition)

A

products continue on to krebs cycle and coenzymes go to participate in ETC

33
Q

Where does transition rxn occur within a cell? Is O2 used during the transition rxn? How many CO2 are given off during the transition rxn? (transition)

A

mitochondria

yes it requires oxygen and releases 2 CO2

34
Q

What is the substrate of Kreb’s cycle? How many ATP are produced during Kreb’s cycle? (kreb’s cycle)

A

substrate:
- 2 acetyl-coA

2 ATP produced

35
Q

Which coenzymes are reduced during Kreb’s cycle? How many of these coenzymes are reduced? Where did the electrons come from to reduce these coenzymes? (kreb’s cycle)

A

6 NAD+ reduced to 6 (NADH + H+) & 2 FAD reduced to 2 FADH2

electrons came from 2 pyruvate

36
Q

Where do reduced coenzymes go when O2 is plentiful? How does this change when the cell is O2 is deficient? (kreb’s cycle)

A

They participate in oxidative phosphorylation.

if no O2 is present the mitochondria power down and relies on glycolysis for atp

37
Q

Where does Kreb’s cycle occur within a cell? Is O2 used during the Kreb’s cycle? How many CO2 are given off during Kreb’s cycle? (kreb’s cycle)

A

mitochondria matrix

yes it uses oxygen and 4 CO2 are given off

38
Q

What is the electron transport chain? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

a series of protein pumps that couple redox reactions to energize the enzymes to pump protons across inner membrane (electrochemical gradient)

39
Q

What happens to the free energy (G) of electrons as they move through the chain? Is this change in free energy positive or negative? Is the ETC endergonic or exergonic? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

the chain goes from higher to lower free energy (-ΔG) meaning it is exergonic (releasing energy)

40
Q

Which substrates/reactants do the electrons bond together (assuming they are available) and what is the resulting product? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

The e– redox via successive ETC proteins / cytochromes ultimately combining with 2 H+ and ½ O2 (FEA) in the mitochondrial matrix to form H2O

41
Q

What is a final electron acceptor (FEA)? Which FEA is used by humans and most mitochondrial-bearing biota? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

It is used as a way to clear the mitochondrial chain of low-energy spent electrons.

oxygen is used into biota to create water

42
Q

The ETC is comprised of proton pumps and cytochromes. Where is the ETC located at within a cell? H+ is pumped from _________________ to __________________ via ______________ transport. [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

located in the mitochondrial inner membrane

mitochondria matrix to mitochondria inter-membrane via active transport

43
Q

How is this proton pumping energized? Where do the electrons come from for pumping? What happens to the oxidized coenzymes after they have dropped off their electrons at the ETC? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

the ETC pumps protons across inner mitochondrial membrane and chemiosmosis uses enzyme atp synthase to pump protons back into the mitochondria matrix which will energize atp synthase to catalyze ADP into ATP

44
Q

An electrochemical gradient forms across the inner mitochondrial membrane as a consequence of the actions of the ETC proton pumps. Where H+ is more concentrated? Which direction would H+ diffuse if it could? What is preventing them from moving with their gradient? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

H+ is more concentrated in the mitochondria inter-membrane.

H+ would diffuse into the matrix if it could.

The inner membrane blocks the movement of H+

45
Q

What is chemiosmosis? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

atp synthase enzyme that uses H+ as energy to catalyze ADP into ATP

46
Q

How do H+ diffuse back across the inner mitochondrial membrane? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

through the protein pumps in an ETC (active transport)

47
Q

Which form of transport occurs when the proton current flows through ATP Synthase? The energy from the proton current through ATP Synthase powers which chemical rxn? How many ATP are made during oxidative phosphorylation? [Oxidative Phosphorylation ATP Production (Slides 14-17)]

A

facilitated diffusion

powers phosphorylation which turns ADP into ATP

makes about 26-28 ATP

48
Q

Which three factors can cause oxidative phosphorylation power down according to the animation?

A
  1. remove oxygen
  2. cyanide
  3. add uncoupling protein
49
Q

What happens to the ETC and chemiosmosis when O2 is not available? Why? How many ATP are made within the mitochondrion when O2 is not available?

A

the chain shuts down and is no longer able to pump protons across the inner membrane.

when the proton gradient is removed, atp synthase can no longe produce ATP.

2 through glycolysis

50
Q

Which pathways do our cells use to produce ATP when O2 is unavailable? Can they do so for very long? What is the fate of cells deprived of oxygen if [O2] does not return to normal?

A

glycolysis. No because only 2 atp produced for every glucose molecule. lead to death

51
Q

When/why does a cell employ the homolactic fermentation pathway? Where does the homolactic fermentation pathway occur?

A

When cell lacks oxygen

it occurs in cytoplasm of both eukaryotes and prokaryotes

52
Q

During homolactic fermentation, pyruvate is oxidized/reduced (circle one) to lactate and NADH is oxidized/reduced (circle one) to NAD+. Knowing about the energetic demands of a typical human cell, do you think it can stay living by glycolysis and homolactic fermentation alone? What is the specific role of homolactic fermentation?

A

pyruvate is reduced into lactate and NADH is oxidized to NAD+

No

the specific role of homolactic fermentation is to regenerate NAD+

53
Q

How does alcoholic fermentation in yeast compare to homolactic fermentation in humans?

A

yeast carry out an extra step where they decarboxylate pyruvate into acetaldehyde and then the acetaldehyde will be reduced to form ethanol

54
Q

Which two products are produced by O2-deficient yeast when they carry out alcoholic fermentation? How do humans use these products in their lives?

A

co2 and ethanol

humans use ethanol for gas, drugs, cosmetics

55
Q

Which pathways are carbohydrates metabolized? Which pathway are fatty acids metabolized? Which pathway is glycerol metabolized? Which pathways are amino acids metabolized?

A

carbohydrates (sugars) - glycolysis
fats (fatty acids) - krebs cycle
fats (glycerol) - glycolysis
proteins (amino acids) - glycolysis or krebs cycle

56
Q

Which toxic byproduct is produced during protein metabolism? How might this by-product impact pH of blood/body fluids? How do humans detoxify the byproduct (hint it is combined with another byproduct from an earlier pathway to make urea)?

A

NH3 (ammonia) is combined with CO2 to form urea which is less toxic that is then sent to your bladder and dilute it out with water

57
Q

What is the overall chemical equation for cellular respiration (including the total number of ATP produced)?

A

1 glucose (C6H12O6) + 6 oxygen (O2) —-> 6 CO2 + 6 H2O —-> heat & 30-32 ATP

Biology 189 (17 decks)

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