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Biology 228: Microbiology > Chapter 8 > Flashcards

Chapter 8 Flashcards

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1
Q

What is metabolism?

A

Chemical reactions that break down or build complex molecules.

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2
Q

What is catabolism?

A

Breaking down complex molecules.

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3
Q

What is anabolism?

A

Building complex molecules.

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4
Q

What are autotrophs?

A

Convert inorganic carbon dioxide into organic carbon.

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5
Q

What are heterotrophs?

A

Use fixed organic carbon compounds.

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6
Q

How do phototrophs get their energy?

A

From light.

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7
Q

How do chemotrophs get their energy? What are the two types of chemotrophs?

A

From chemical compounds.
- Organotrophs
- Lithotrophs

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8
Q

How do organotrophs get energy?

A

Through organic molecules.

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9
Q

How do lithotrophs get energy?

A

Through inorganic molecules.

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10
Q

What does O.I.L. R.I.G. stand for?

A

O.I.L. - Oxidation is Loss of electrons
R.I.G. - Reduction is Gain of electrons

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11
Q

What do cellular electron carriers do?

A

Accept high-energy electrons from food and later serve as electron donors in subsequent redox reactions.

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12
Q

What are the types of electron carriers?

A

FAD/FADH2
NAD+/NADH
NADP+/NADPH

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13
Q

Which electron carriers are important for extraction of sugars during catabolism?

A

NAD+/NADH
FAD/FADH2

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14
Q

Which electron carriers are important for anabolic reactions?

A

NADP+/NADPH

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15
Q

What is an endergonic reaction?

A

Reaction that requires an input of energy to proceed (unfavorable).

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16
Q

What is an exergonic reaction?

A

Reaction that releases energy into its surroundings (favorable).

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17
Q

What is the currency of the cell?

A

Adenosine triphosphate (ATP).

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18
Q

What does ATP do?

A

Safely stores chemical energy in its two high-energy phosphate bonds for later use to drive processes requiring energy.

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19
Q

What is dephosphorylation?

A

Energy is released to drive endergonic reactions.

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20
Q

What are enzymes?

A

Enzymes (proteins) are biological catalysts that increase the rate of chemical reactions inside cells by lowering the activation energy required for the reaction to proceed.
They are pH and temperature dependent.

21
Q

What is an induced fit?

A

Substrates bind to the enzyme’s active site. This process typically alters the structures of both the active site and the substrate, favoring transition-state formation.

22
Q

What are cofactors?

A

Inorganic ions that stabilize enzyme conformation and function.

23
Q

What are coenzymes?

A

Organic molecules required for proper enzyme function and are often derived from vitamins.

24
Q

What is an enzyme without a cofactor or coenzyme called?

A

An apoenzyme

25
Q

What is an enzyme that has a cofactor or coenzyme attached called?

A

A holoenzyme

26
Q

What do competitive inhibitors do?

A

Regulate enzymes by binding to an enzyme’s active site, preventing substrate binding.

27
Q

What do noncompetitive (allosteric) inhibitors do?

A

Bind to allosteric sites (not active site), inducing a conformational change in the enzyme that prevents it from functioning.

28
Q

What do feedback inhibitions do?

A

They will use products of the reaction to inhibit enzymes.

29
Q

What is glycolysis?

A

It is the first step in the breakdown of glucose –> formation of ATP, NADH and two pyruvate molecules.

30
Q

Is glycolysis aerobic or anerobic?

A

Glycolysis does not use oxygen and is not oxygen dependent. Therefore anerobic.

31
Q

What is the transition reaction?

A

Takes place after glycolysis –> a three-carbon pyruvate is decarboxylated to form a two-carbon acetyl group, coupled with the formation of NADH.
- The acetyl group is attached to a large carrier compound called coenzyme A

32
Q

What is the Krebs Cycle?

A

After the transition step, coenzyme A transports the two-carbon acetyl to the Krebs cycle, where the two carbons enter the cycle.
Each time through the cycle, one acetyl group derived from glycolysis is further oxidized = 3 NADH molecules, 1 FADH2, and 1 ATP by substrate-level phosphorylation, and releasing 2 CO2 molecules.

33
Q

How is most ATP generated during cellular respiration?

A

By oxidative phosphorylation.

34
Q

What are the steps of cellular respiration?

A
  1. Electrons transferred from NADH and FADH2 (made on glycolysis, the transition reaction, and the Krebs cycle)
  2. They go through a series of chemical reactions
  3. Arrives at final inorganic electron acceptor
35
Q

Where is the electron transport system (ETS)?

A

The ETS is embedded in the cytoplasmic membrane of prokaryotes and the inner mitochondrial membrane of eukaryotes.

36
Q

What does aerobic respiration require?

A
  • Oxygen as the final electron acceptor –> reduction to H2O
  • A complete Krebs cycle
  • An appropriate cytochrome oxidase
  • Oxygen detoxification enzymes to prevent the harmful effects of oxygen radicals produced during aerobic respiration
37
Q

What could aerobic respiration not be possible?

A
  • The cell lacks genes encoding an appropriate cytochrome oxidase for transferring electrons to oxygen.
  • The cell lacks genes encoding enzymes to minimize the severely damaging effects of dangerous oxygen radicals produced during aerobic respiration, such as hydrogen peroxide (H2O2) or superoxide (O2-)
  • The cell lacks a sufficient amount of oxygen to carry out aerobic respiration
38
Q

What is the difference between aerobic and anaerobic respiration?

A
  • Anaerobic respiration use alternative electron transport system carriers for the ultimate transfer of electrons to the final non-oxygen electron acceptors.
  • Aerobic produces 34 ATP molecules and Anaerobic produces 32 ATP molecules
39
Q

What is fermentation?

A

Fermentation uses an organic molecule (commonly pyruvate) as a final electron acceptor to regenerate NAD+ from NADH so that glycolysis can continue.

40
Q

Is fermentation related to the ETS?

A

Fermentation does not involve an electron transport system, and no ATP is made by the fermentation process directly. Fermenters make very little ATP.

41
Q

What happens during lactic acid fermentation?

A

Pyruvate accepts electrons from NADH and is reduced to lactic acid.
Lactic acid production by the normal microbiota prevents growth of pathogens in certain body regions and is important for the health of the gastrointestinal tract.

42
Q

Homolactic versus heterolactic?

A

Microbes performing homolactic fermentation produce only lactic acid as the fermentation product; microbes performing heterolactic fermentation produce a mixture of lactic acid, ethanol and/or acetic acid, and CO2.

43
Q

What are the three types of lipids that can be degraded?

A

Triglycerides, phospholipids, and fatty acids

44
Q

How does triglyceride catabolism work?

A

Degraded by extracellular lipases, releasing fatty acids from the glycerol backbone.

45
Q

How does phospholipid catabolism work?

A

Degraded by phospholipases, releasing fatty acids and the phosphorylated head group from the glycerol backbone.
Lipases and phospholipases act as virulence factors for certain pathogenic microbes.

46
Q

How does fatty acid catabolism work?

A

They can be further degraded inside the cell through β-oxidation, which sequentially removes two-carbon acetyl groups from the ends of fatty acid chains –> NADH and FADH2 production –> oxidative phosphorylation = ATP

47
Q

What does protein catabolism involve?

A

Involves extracellular proteases that degrade large proteins into smaller peptides.

48
Q

How can we differentiate clinically relevant bacteria in protein catabolism?

A

Detection of the extracellular proteases gelatinase and caseinase.

49
Q

Autostudy Photosynthesis

A

Biology 228: Microbiology (20 decks)

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