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BIOL 351 > Catabolism > Flashcards

Catabolism Flashcards

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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
Why is TCA cycle special?
It can full oxidize all 3 carbons of pyruvate to produce the maximum amount of ATP possible. It is amphibolic.
26
Where is TCA in prokaryotes? In eukaryotes?
In prokaryotes it's in cytosol. In eukaryotes its in mitochondrial matrix.
27
What makes the most ATP in respiration?
The oxidation of NADH and FADH2 in the ETC
28
How many H+ must be transported to make 1 ATP?
4H+
29
How many ATP does 1 NADH make?
1 NADH moves 10H+ so about 2.5 ATP
30
How mang ATP does 1 FADH2 make?
1 FADH2 moves 6H+ so about 1.5 ATP
31
What is the maximum amount of ATP that can be made in aerobic respiration?
32 is the max
32
What is the equation for the TCA cycle for one molecule of glucose?
2 Pyruvate + 2 GDP + 2Pi + 2 FAD + 8 NAD --> 6 CO2 + 2 GTP + 8 NADH + 2 FADH2 + 8 H+
33
Why do we not usually see the max number of ATP produced?
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
What are the terminal electron acceptors for anaerobic respiration?
NO3 (nitrate), SO3 (sulfate), CO2
35
What produces most of the ATP in anaerobic respiration?
Oxidative phosphorylation in ETC
36
What's different about bacterial ETCs for anaerobic respiration?
They are branched with different carrier proteins
37
Why is less ATP produced in anaerobic respiration?
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
Fermentation is found in which organisms?
those that lack ETCs or repress their synthesis under anoxic conditions which makes anaerobic respiration impossible
39
How is ATP made in fermentation?
by substrate-level phosphorylation only
40
What is the final electron acceptor in fermentation?
pyruvate or one of its derivatives
41
What are the 4 important factors of fermentation
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
What is true of the substrate in a fermentation reaction?
substrates in fermentation reactions are only partially oxidized (not energy efficient or conservative)
43
What happens to ATPas during fermentation?
It is used in the reverse direction to pump H+ out to generate a PMD using energy from ATP hydrolysis
44
How does fermentation of carbohydrates other than glucose work?
Polysaccharides are cleaved by BOTH hydrolysis and phosphorolysis (split by phosphate attack) e.g.) starch, glycogen, cellulose
45
How does lipid catabolism work?
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
What does 1 turn of lipid catabolism produce?
1 acetyl-CoA, 1 NADH, 1 FADH2
47
What happens in protein catabolism?
Proteins are hydrolyzed into amino acids by proteases
48
What does deamination do?
It remobes the amino group of an amino acid by a transamination reaction
49
How is excessive nitrogen removed?
it's excreted as ammonium ions
50
Chemolithotrophic fueling
sends electrons to ETC by oxidizing inorganic molecules instead of organic nutrients
51
What are the typical reduced inorganic moleucles used in chemolithotrophy?
H2, NO2-, NH4+, S, H2S, Fe2+
52
Why is less energy released in chemolithotrophy?
because electron donors have a much more positibe reduction potential compared to glucose (which is more negative and thus better)
53
What is the final electron acceptor in chemolithotrophy?
it's usually oxygen after the ETC
54
Phototrophic fueling
uses light energy to drive PMF and thus ATP synthesis
55
What are the two types of phototrophic fueling?
Chlorophyll-based and Rhodopsin-based
56
How does chlorophyll contribute to energy production?
Chlorophyll absorbs light and starts its conversion to chemical energy in a process chemiosmosis
57
How does type of chlorophyll indicate ecological niche?
by absorption of different wavelengths
58
What two energy products are produced by photosynthesis
ATP and NADPH
59
How do phototrophs work?
phototrophs use light to create PMF which is used to synthesize ATP by a process called photophosphorylation
60
What happens in chlorophyll-based phototrophs
absorption of light by pigments triggers flow of electrons through a ETC
61
What is rhodopsin?
a transmembrane protein attached to a chromophore similar to what's found in eyes of multicellular organisms
62
How is rhodopsin-based phototrophy different from chlorophyll-based
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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