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Biology 260 > Unit 4 > Flashcards

Unit 4 Flashcards

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1
Q

Where does glycolysis occur in a eukaryotic cell?

A

Cytoplasm

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2
Q

Where does the TCA (or Kreb cycle) occur in a eukaryotic cell?

A

Mitochondrial matrix

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3
Q

Where does the electron transport chain occur in the eukaryotic cell?

A

Mitochondrial inner membrane

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4
Q

Glycolysis:

A

Breaks down glucose (oxidation) into pyruvate to make energy (ATP)

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5
Q

TCA (or Krebs):

A

Releases energy from acetyl-CoA through a series of reactions that yields energy as NADH, FADH2, and ATP

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6
Q

Substrate-level phosphorylation:

A

Generates ATP, by direct transfer of phosphate from a metabolic compound to ADP

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6
Q

Photophosphorylation:

A

The light-dependent reaction of photosynthesis

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7
Q

Oxidative phosphorylation:

A

The ETC transfers electrons from an organic compound to oxygen

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8
Q

Fermentation:

A

Lactic acid and ethanol are the end-products of this pathway when pyruvate accepts electrons

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9
Q

What processes does photosynthesis involve?

A

Light-dependent photophosphorylation

&

Calvin-Benson cycle

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10
Q

What is the Calvin-Benson cycle?

A

aka Calvin cycle or the light-independent reactions is the part of photosynthesis where plants synthesize glucose from CO₂ using ATP and NADPH produced during the light-dependent reactions

Takes place in the stroma of chloroplasts and doesn’t require light to proceed

This cycle involves three main stages:

  1. Carbon fixation: CO₂ is attached to a 5-carbon molecule (RuBP).
  2. Reduction phase: The resulting molecules are converted into G3P (glyceraldehyde-3-phosphate), a sugar precursor.
  3. Regeneration of RuBP: Some G3P molecules are used to regenerate RuBP, allowing the cycle to continue
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11
Q

Glycolysis yields energy in which form?

A

NADH and ATP

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12
Q

What are the steps in the Energy Investment phase in glycolysis (1-5)

A

Energy Investment Phase:
1. Glucose Phosphorylation
- Glucose → G6P
- Enzyme: Hexokinase
- 1 ATP is used.

  1. Isomerization
    - G6P → Fructose6P
    - Enzyme: Phosphoglucose isomerase
  2. Second Phosphorylation
    - F6P → Fructose-1,6-bisphosphate (F1,6BP)
    - Enzyme: Phosphofructokinase-1 (PFK-1)
    • 1 ATP is used.
  3. Cleavage (Step for which glycolysis is named)
    - F1, 6BP → G3P and Dihydroxyacetone phosphate (DHAP)
    - Enzyme: Aldolase
  4. Isomerization of DHAP
    - DHAP → Glyceraldehyde-3-phosphate (G3P) Enzyme: Triose phosphate isomerase
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13
Q

What are the steps in the Energy Payoff phase in glycolysis (6-10)

A

Energy Payoff Phase:

  1. Oxidation and Phosphorylation
    • Glyceraldehyde-3-phosphate (G3P) → 1,3-bisphosphoglycerate (1,3-BPG)
    • Enzyme: Glyceraldehyde-3-phosphate dehydrogenase
    • NAD+ is reduced to NADH.
  2. First ATP Generation
    • 1,3-bisphosphoglycerate → 3-phosphoglycerate
    • Enzyme: Phosphoglycerate kinase
    • 1 ATP is produced per molecule of G3P.
  3. Phosphate Shift
    • 3-phosphoglycerate → 2-phosphoglycerate
    • Enzyme: Phosphoglycerate mutase
  4. Dehydration
    • 2-phosphoglycerate → Phosphoenolpyruvate (PEP)
    • Enzyme: Enolase
    • Water is removed.
  5. Second ATP Generation
    - Phosphoenolpyruvate (PEP) → Pyruvate
    - Enzyme: Pyruvate kinase
    - 1 ATP is produced per molecule of PEP.
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14
Q

Which step is the step for which glycolysis is named?

A

4th (Cleavage)

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15
Q

What is meant by substrate-level phosphorylation?

A

Production of ATP by transferring phosphates directly from metabolic products to ADP

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16
Q

What is the driving force of energy production in steps 6 and 7?

A

The oxidation of three-carbon compounds

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17
Q

How much net ATP is produced during glycolysis?

A

2 ATP

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18
Q

Which of the following is needed as a reactant for the first step of the citric acid cycle?

A

Oxaloacetic acid

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19
Q

Where does the energy come from to power the formation of GTP?

A

Succinyl CoA

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20
Q

Which step of the Krebs cycle involves the release of carbon dioxide?

A

The third and fourth steps

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21
Q

What are the steps of the Krebs cycle? (8)

A

Krebs Cycle Steps:

  1. Condensation
    • Reactants: Acetyl CoA + Oxaloacetate
    • Product: Citrate (citric acid)
    • Enzyme: Citrate synthase
    • Note: Acetyl CoA donates a 2-carbon acetyl group, and oxaloacetate is regenerated.
  2. Isomerization
    • Reactant: Citrate
    • Product: Isocitrate
    • Enzyme: Aconitase
    • Note: Citrate is rearranged into its isomer, isocitrate.
  3. First Decarboxylation
    • Reactant: Isocitrate
    • Products: α-Ketoglutarate + CO₂
    • Enzyme: Isocitrate dehydrogenase
    • Note: NAD⁺ is reduced to NADH.
  4. Second Decarboxylation
    • Reactant: α-Ketoglutarate
    • Products: Succinyl CoA + CO₂
    • Enzyme: α-Ketoglutarate dehydrogenase
    • Note: Another NAD⁺ is reduced to NADH.
  5. Substrate-Level Phosphorylation
    • Reactant: Succinyl CoA
    • Product: Succinate + GTP (or ATP)
    • Enzyme: Succinyl-CoA synthetase
    • Note: The high-energy thioester bond in succinyl CoA is used to generate GTP.
  6. Oxidation
    • Reactant: Succinate
    • Product: Fumarate
    • Enzyme: Succinate dehydrogenase
    • Note: FAD is reduced to FADH₂.
  7. Hydration
    • Reactant: Fumarate
    • Product: Malate
    • Enzyme: Fumarase
    • Note: Water is added to fumarate.
  8. Second Oxidation
    • Reactant: Malate
    • Product: Oxaloacetate
    • Enzyme: Malate dehydrogenase
    • Note: NAD⁺ is reduced to NADH, and oxaloacetate is regenerated for the cycle to continue
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22
Q

How many molecules of ATP can be generated from 1 molecule of NADH?

A

3

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23
Q

Which step(s) of the Krebs cycle does (do) not produce any usable energy?

A

2nd (Isomerization)

&

7th (Hydration)

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24
Q

Why does FADH2 yield less ATP than NADH?

A

FADH2 electrons enter the ETC at a lower energy level

25
Q

What can be used as a final electron acceptor for aerobic respiration?

A

Molecular oxygen

26
Q

What is one difference between cytochromes and ubiquinones?

A

Cytochromes are made of protein; Ubiquinones are not

27
Q

How does the proton gradient help ATP synthase to make ATP?

A

Protons move from outside the membrane to inside the membrane.

28
Q

Iron is considered an essential element for many bacteria. Based on the steps of the electron transport chain, how would lack of iron affect energy production of a bacterium?

A

Lack of iron -> lack of heme -> lower amounts of functioning cytochrome proteins -> lower energy yields

29
Q

What is an alternative way to return electron carriers to their oxidized state?

A

Fermentation

30
Q

What is the role of pyruvic acid in fermentation?

A

Oxidizes NADH back into NAD+

31
Q

What is the fate of the NAD+ newly regenerated by fermentation?

A

It returns to glycolysis to pick up more electrons

32
Q

What are two acids produced by fermentation?

A

Lactic acid & acetic acid

propionic acid

33
Q

What is the intermediate product formed by pyruvic acid during alcoholic fermentation?

A

Acetaldehyde

34
Q

Chemiosmosis uses __________ to supply the energy necessary to phosphorylate ADP to ATP

A

a protein gradient

35
Q

What is Chemiosmosis?

A

ATP is generated in cells through the movement of protons (H⁺ ions) across a membrane, driven by an electrochemical gradient;

leading to the phosphorylation of ADP to ATP via ATP synthase

36
Q

Where is the majority of ATP generated in prokaryotic cells?

A

In the cytoplasmic membrane;

because that’s where the ETC is

37
Q

Methanogens are bacteria that ____

A

convert CO2 and hydrogen to methane

38
Q

Green sulfur bacteria oxidize ___ to ___.

A

Green sulfur bacteria oxidize hydrogen sulfide to sulfate

39
Q

Nitrification:

A

Ammonia is converted to nitrite, then nitrate.

40
Q

Denitrification:

A

Nitrate is converted to nitrogen gas

41
Q

Ammonification:

A

Amino acids are converted to NH3 (ammonia)

42
Q

Nitrogen fixation:

A

Nitrogen gas -> ammonia

43
Q

What does Oxidation of sulfur result in?

A

The production of sulfate

44
Q

What are Sulfate and nitrate?

A

The most readily used forms used by plants

45
Q

How does Reduction of sulfur occur?

A

Sulfate is converted by bacteria to Hydrogen sulfide

46
Q

What can leaching of sulfate produced by bacteria cause?

A

It can cause waterways to become acidic

47
Q

What bacteria do Photoheterotrophs contain?

A

Green and purple non-sulfur bacteria

48
Q

What bacteria do Photoautotrophs contain?

A

Use H2O to reduce CO2?

Yes: Cyanobacteria

No: Green and purple sulfur bacteria

49
Q

Which type of organism uses hydrogen sulfide for reducing power?

A

Purple sulfur bacteria;

Purple sulfur bacteria employ anoxygenic photosynthesis with hydrogen gas, sulfur compounds such as hydrogen sulfide, or sulfur as an electron donor (reducing power) in photosynthesis

50
Q

In which organism would you likely find a chlorosome?

A

Green sulfur bacteria;

Chlorosomes, or chlorobium vesicles, house bacteriochlorophylls

51
Q

What is a bacterium that performs oxygenic photosynthesis?

A

Cyanobacteria;

Like plants and algae, cyanobacteria are oxygenic; meaning that their photosynthetic process generates oxygen

52
Q

What is the key difference between photoheterotrophs and photoautotrophs?

A

Photoheterotrophs use organic compounds as their carbon source;

photoautotrophs use CO2 as their carbon source.

53
Q

What is a trait unique to photosynthetic eukaryotes?

A

The presence of chloroplasts;

Chloroplasts are membrane-bound organelles, and thus unique to eukaryotes

54
Q

Lipases break down ____

A

lipids

55
Q

The Pentose Phosphate Pathway ____
(process)

A

is an example of anabolism

56
Q

What is fermentation considered as?
(process)

A

Catabolism

57
Q

What kind of reaction is photosynthesis? (process)

A

Anabolic

58
Q

What process is oxidative phosphorylation?

A

A catabolic process

59
Q

The reactions that occur between glucose and pyruvic acid can be either ____

A

anabolic or catabolic

60
Q

Which location is LEAST likely to contain methanogens?

A

Surface of ice in the Antarctic;

Methanogens are anaerobic microorganisms the surface of ice in the Antarctic is an extreme environment with low temperatures and low organic matter availability

61
Q

Without the light-dependent reactions of photosynthesis, the Calvin-Benson cycle would not be possible because it would lack which molecules?

A

ATP and NADPH

Biology 260 (35 decks)

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