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BIOL 351 > Catabolism > Flashcards

Catabolism Flashcards

1
Q

Chemoorganotrophs

A

oxidize organic (naturally reduced) energy sources resulting in those sources being oxidized

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2
Q

Fueling Reactions make what 3 main products?

A
  1. ATP
  2. Reducing Power
  3. Precursor Metabolites
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3
Q

Two Types of Fueling Reactions

A
  1. Respiration

2. Fermentation

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4
Q

Respiration has two types

A

Aerobic - uses exogenous O2 as final electron acceptor.

Anaerobic - uses alt exogenous acceptor like nitrate, sulfate, carbon dioxide and iron

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5
Q

Respiration is defined by the use of

A

an exogenous final electron acceptor

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6
Q

Oxidative Phosphorylation

A

process in respiration that uses the ETC to make PMF that is used for ATP synthesis and biosynthesis. Occurs in both aerobic AND anaerobic respiration.

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7
Q

What type of phosphorylation does Fermentation use?

A

substrate level only

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8
Q

Where is ETC not used?

A

Fermentation

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9
Q

What are the three stages of aerobic respiration?

A
  1. Large nutrient molecules are broken down into constituent parts.
  2. Constituent Parts are further oxidized into metabolites (e.g. acetyl CoA, Pyruvate, etc.)
  3. Partially oxidized products are fully oxidized to produce NADS, FADH2, and ATP
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10
Q

Glycolytic Pathways…

A

degrade sugars into pyruvate and related intermediates

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11
Q

What are the 3 major glycolytic pathways?

A
  1. Embden-Meyerhof (EMP) - very common; hexose to pyruvate.
  2. Entner-Doudoroff (EDP) - rare; hexose to pyruvate
  3. Pentose-Phosphate (PPP) - common; biosynthesis
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12
Q

Glycolysis location, oxygen need, organism specificity

A

takes place in the cytoplasm, can occur with or without oxygen, occurs in all organisms

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13
Q

What do catabolic pathways do? What does it lead to?

A

Degrade many nutrients into a few metabolic intermediates. This leads to increased efficiency and flexibility

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14
Q

Amphibolic Pathways

A

those that are reversible that is, they can be used catabolically and anabolically (macromolecule synthesis)

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15
Q

Is EMP amphibolic? How does its enzymes work? How does this achieve efficiency

A
  1. most enzymes are used in glycolysis and gluconeogenesis.
  2. some enzymes are unidirectional
  3. increases energy conservation by resulting in fewer enzymes for metabolism and regulation of catabolic/anabolic activity
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16
Q

What type of phosphorylation occurs in EMB?

A

Substrate level only

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17
Q

What is the equation for EMB?

A

Glucose + 2ADP + 2Pi + 2NAD –> 2 Pyruvate + 2 ATP + 2NADH + 2 H+

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18
Q

What is the equation for EDP?

A

Glucose + ADP + Pi + NADP + NAD –> 2 Pyruvate + ATP + NADPH + NADH + 2 H+

NADPH used for anabolic reductions

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19
Q

What uses the EDP?

A

Soil and other gram (-) bacteria
NOT used by eukaryotes
only uses substrate-level phosphorylation

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20
Q

What is the equation for the PPP?

A

G6P + 12 NADP + 7 H2O –> 6 CO2 + 12 NADPH + Pi + 12 H+

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21
Q

Does PPP need oxygen?

A

No, it can function aerobically or anaerobically

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22
Q

What is the PPP important for?

A

It’s important for both anabolic and catabolic reactions

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23
Q

What are three important precursor metabolites from PPP and their uses?

A
  1. Erythrose-4-Phosphate: used in aromatic amino acid and Vitamin B6 ss\ynthesis
  2. Ribose-5-Phosphate: Used in nucleotide synthesis for DNA/RNA
  3. Intermediates: can be used for ATP production if oxidized or anabolic reactions elsewhere
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24
Q

How many NADPH are made from one glucose in PPP?

A

2 NADPH per glucose

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25
Q

Why is TCA cycle special?

A

It can full oxidize all 3 carbons of pyruvate to produce the maximum amount of ATP possible.
It is amphibolic.

26
Q

Where is TCA in prokaryotes? In eukaryotes?

A

In prokaryotes it’s in cytosol. In eukaryotes its in mitochondrial matrix.

27
Q

What makes the most ATP in respiration?

A

The oxidation of NADH and FADH2 in the ETC

28
Q

How many H+ must be transported to make 1 ATP?

A

4H+

29
Q

How many ATP does 1 NADH make?

A

1 NADH moves 10H+ so about 2.5 ATP

30
Q

How mang ATP does 1 FADH2 make?

A

1 FADH2 moves 6H+ so about 1.5 ATP

31
Q

What is the maximum amount of ATP that can be made in aerobic respiration?

A

32 is the max

32
Q

What is the equation for the TCA cycle for one molecule of glucose?

A

2 Pyruvate + 2 GDP + 2Pi + 2 FAD + 8 NAD –> 6 CO2 + 2 GTP + 8 NADH + 2 FADH2 + 8 H+

33
Q

Why do we not usually see the max number of ATP produced?

A
  1. bacterial ETCs transport fewer H+ because their ETCs are shorter
  2. PMF can be diverted to other things than ATP such as active transport
  3. Precursor intermediates may be directed to anabolic reactions instead of being oxidized for energy production.
34
Q

What are the terminal electron acceptors for anaerobic respiration?

A

NO3 (nitrate), SO3 (sulfate), CO2

35
Q

What produces most of the ATP in anaerobic respiration?

A

Oxidative phosphorylation in ETC

36
Q

What’s different about bacterial ETCs for anaerobic respiration?

A

They are branched with different carrier proteins

37
Q

Why is less ATP produced in anaerobic respiration?

A

the alternative final electron acceptors used have LESS positive/MORE negative reduction potential compared to oxygen.
The leads to fewer H+ moved, so lower PMF, and thus less ATP produced.

38
Q

Fermentation is found in which organisms?

A

those that lack ETCs or repress their synthesis under anoxic conditions which makes anaerobic respiration impossible

39
Q

How is ATP made in fermentation?

A

by substrate-level phosphorylation only

40
Q

What is the final electron acceptor in fermentation?

A

pyruvate or one of its derivatives

41
Q

What are the 4 important factors of fermentation

A
  1. NADH must be oxidized to NAD+ for glycolysis to continue
  2. Oxygen is not needed
  3. final electron acceptor is pyruvate or one of its derivatives
  4. ETC cannot operate which results in only a few ATP made
42
Q

What is true of the substrate in a fermentation reaction?

A

substrates in fermentation reactions are only partially oxidized (not energy efficient or conservative)

43
Q

What happens to ATPas during fermentation?

A

It is used in the reverse direction to pump H+ out to generate a PMD using energy from ATP hydrolysis

44
Q

How does fermentation of carbohydrates other than glucose work?

A

Polysaccharides are cleaved by BOTH hydrolysis and phosphorolysis (split by phosphate attack)

e.g.) starch, glycogen, cellulose

45
Q

How does lipid catabolism work?

A

Fatty Acid Beta-Oxidation
Removes 2-Carbon units at a time and releases the as Acetyl-CoA
Uses triacylglycerols (glycerol core with 3 fatty acid chains)

46
Q

What does 1 turn of lipid catabolism produce?

A

1 acetyl-CoA, 1 NADH, 1 FADH2

47
Q

What happens in protein catabolism?

A

Proteins are hydrolyzed into amino acids by proteases

48
Q

What does deamination do?

A

It remobes the amino group of an amino acid by a transamination reaction

49
Q

How is excessive nitrogen removed?

A

it’s excreted as ammonium ions

50
Q

Chemolithotrophic fueling

A

sends electrons to ETC by oxidizing inorganic molecules instead of organic nutrients

51
Q

What are the typical reduced inorganic moleucles used in chemolithotrophy?

A

H2, NO2-, NH4+, S, H2S, Fe2+

52
Q

Why is less energy released in chemolithotrophy?

A

because electron donors have a much more positibe reduction potential compared to glucose (which is more negative and thus better)

53
Q

What is the final electron acceptor in chemolithotrophy?

A

it’s usually oxygen after the ETC

54
Q

Phototrophic fueling

A

uses light energy to drive PMF and thus ATP synthesis

55
Q

What are the two types of phototrophic fueling?

A

Chlorophyll-based and Rhodopsin-based

56
Q

How does chlorophyll contribute to energy production?

A

Chlorophyll absorbs light and starts its conversion to chemical energy in a process chemiosmosis

57
Q

How does type of chlorophyll indicate ecological niche?

A

by absorption of different wavelengths

58
Q

What two energy products are produced by photosynthesis

A

ATP and NADPH

59
Q

How do phototrophs work?

A

phototrophs use light to create PMF which is used to synthesize ATP by a process called photophosphorylation

60
Q

What happens in chlorophyll-based phototrophs

A

absorption of light by pigments triggers flow of electrons through a ETC

61
Q

What is rhodopsin?

A

a transmembrane protein attached to a chromophore

similar to what’s found in eyes of multicellular organisms

62
Q

How is rhodopsin-based phototrophy different from chlorophyll-based

A

there is no ETC in rhodopsin-based phototrophy.

Light reacts with rhodopsin which directly creates a PMF to power chemiosmosis which synthesizes ATP

BIOL 351 (1 decks)

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