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MCAT > Metabolism > Flashcards

Metabolism Flashcards

1
Q

Regulatory enzymes of Glycolysis

A

Hexokinase (Glucose → G-6P)- ATP in
PFK (F6P → F 1,6-bisphosphate)- ATP in
Pyruvate kinase (PEP → Pyruvate)- ADP in

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2
Q

Rate-limiting step of glycolysis

A

PFK catalyzes F6P → F 1,6-bisphosphate

- F6P is phosphorylated using ATP

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3
Q

Net Yield of Glycolysis

A

2 ATP, 2 NADH, 2 pyruvate

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4
Q

Oxidoreductases

A

catalyze redox reactions that transfer electrons

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5
Q

Transferases

A

move a functional group from one molecule to another

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6
Q

Hydrolase

A

catalyze cleavage with the addition of water

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7
Q

Lyase

A

catalyze cleavage without the addition of water or transfer of electrons
- synthase is the opposite

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8
Q

Isomerase

A

catalyze the interconversion of isomers, including both constitutional isomers and stereoisomers

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9
Q

Ligase

A

join two large biomolecules (often the same type)

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10
Q

NADH vs NADPH

A 
NADPH is used in synthesis pathways (like PPP): 
fatty acid
cholesterol
neurotransmitter
Nucleotide
It is similar to NADH, except:
additional phosphate group
enables binding discrimination
can be reduced more
NADH is used in all other metabolic pathways

Both:
reductive agent

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11
Q

protease

A

protein that hydrolyzes (cleaves) another protein; hydrolyzes peptide bonds

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12
Q

lipase

A

enzyme that hydrolyzes fats

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13
Q

kinase

A

transfers a phosphate group to a molecule from a high energy carrier, such as ATP

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14
Q

polymerase

A

synthesizes long chains of polymers or nucleic acids

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15
Q

phosphatase

A

removes a phosphate group from a molecule (“undoes” a kinase)

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16
Q

phosphorylase

A

transfers a phosphate group to a molecule from inorganic phosphate

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17
Q

ATP synthase

A

large protein complex that synthesizes ATP from ADP +Pi

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18
Q

exonuclease

A

cutting a nucleic acid chain at the end

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19
Q

endonuclease

A

will cut a polynucleotide acid chain in the middle of the chain, at a particular sequence
- ex) repair enzymes and restriction enzymes

20
Q

caspases

A

part of the protease family; responsible for carrying out the events of apoptosis; consist of initiator caspases, which respond to extracellular and intracellular signals, which then activate the effector caspases, which cleave a variety of cellular proteins to trigger apoptosis. upon this, there is an amplification cascade. (usually inactive in zymogen form)

21
Q

Energy input phase of glycolysis

A

2 phosphate groups from 2 ATP are added to glucose, trapping it inside the cell and split it into DHAP and G3P

22
Q

Energy output phase

A

Energy created in the second half of glycolysis

23
Q

Substrate level phosphorylation

A

The direct transfer of a phosphate group from a reactive intermediate onto ADP or GDP by kinase enzyme

24
Q

When glucose is abundant, it comes from the _______________. When it is limited, it comes from the _________________________.

A

Intestines ; liver

25
Q

Ammonia goes into the _____ cycle and the carbon chain acts as a substrate for the ________ cycle

A

Urea cycle—>urine ; citric acid cycle

26
Q

Why can muscles release glucose for other organs to use?

A

They do not have the necessary phosphatase to release glucose from the cell.

27
Q

glycogen synthase

A

creates alpha 1,4 glycosidic links between glucose molecules (makes glycogen)
- activated by insulin in liver and muscle

28
Q

Branching enzyme

A

moves a block of oligoglucose from one chain and adds it to the growing glycogen as a new branch at an alpha 1,6 glycosidic link

29
Q

Glycogen phosphorylase

A

removes a single glucose 1-phosphate molecules by breaking alpha 1,4 glycosidic links

  • activated by glucagon (liver) to prevent low blood sugar
  • activated by epinephrine and AMP (exercising skeletal muscle) to provide glucose for muscle
30
Q

Debranching enzyme

A

moves a block of oligoglucose from one branch and connects it to the chain using an alpha 1,4 glycosidic link. it also removes the branch points (an alpha 1,6 glycosidic link)- releases a free glucose

31
Q

control of pyruvate dehydrogenase

A

pyruvate dehydrogenase converts pyruvate to acetyl-CoA

  • stimulated by insulin
  • inhibited by acetyl-coA
32
Q

When oxygen or mitochondria are absent, NADH from gylcolysis is oxidized by ___.

A

cytoplasmic lactate dehydrogenase

- in RBCs, skeletal muscle during short, intense bursts of exercise, and oxygen deprived cells

33
Q

pentose phosphate pathway

A
  • aka the HMP shunt
  • occurs in cytoplasm of most cells
  • generates NADPH and ribose sugars for biosynthesis
34
Q

rate limiting enzyme of PPP

A

glucose-6-phosphate-dehydrogenase

  • G-6-PD is activated by NADP+ and insulin
  • inhibited by NADPH
35
Q

dehydrogenases

A

which remove one or more hydrogen atoms from their substrates
- cofactors are NAD+ and FAD

36
Q

NAD+ and FAD

A
  • serve as oxidizing agents, accepting a pair of electrons, along with one or more protons, to switch to their reduced forms
  • NAD+ accepts two electrons and one H+ to become NADH
  • FAD accepts two electrons and two H+ to become FADH2
  • NAD+ is the primary electron carrier used during cellular respiration, with FAD participating in just one (or two sometimes two) reactions
37
Q

Water soluble electron carriers

A

NADH, FADH2, NADPH

38
Q

Fat soluble electron carriers

A

membrane proteins in the electron transport chain (FMN, CoQ, iron-sulfur complexes, cytochromes)

39
Q

TOTAL net ATP produced per glucose

A

theoretically 38 (2 from glycolysis, 2 from citric acid cycle, 24 from ETC), actually ~30

40
Q

Glycolysis product

A

2 Pyruvate, 2 NADH, and 2 ATP

41
Q

Regulators of glycolysis

A
  • inhibited by ATP.

Feeder pathways: breakdown of glycogen and starch (in plants) forms glucose units, which feeds into glycolysis

42
Q

Inhibitor of glycolysis

A

ATP.

Feeder pathways: breakdown of glycogen and starch (in plants) forms glucose units, which feeds into glycolysis

43
Q

Steps of aerobic metabolism (needs oxygen)

A

Glycolysis
Oxidative decarboxylation
Krebs cycle
Electron transport chain.

Net: 6 CO2, 6 H2O, and up to 30 ATP from each molecule of glucose

44
Q

germ layers and what they produce

A

ectoderm. Its the most superficial, so think if skin.
Mesoderm, bone and muscles.
Endoderm, gut and reproductive trac

45
Q

Steps of anaerobic metabolism (don’t need oxygen)

A

Glycolysis
Alcohol or lactic acid fermentation

Net: 2 ATP, Lactic Acid (animals) or EtOH (plants)

MCAT (4 decks)

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