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NBDE 1 > Metabolic Pathways > Flashcards

Metabolic Pathways Flashcards

1
Q

What is the rate limiting enzyme for glycolysis?

A

Phosphofructokinase

PFK

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2
Q

What is the rate limiting enzyme for gluconeogenesis?

A

fructose bisphosphatase-2

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3
Q

What is the rate limiting enzyme for TCA cycle

A

isocitrate dehydrogenase

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4
Q

What is the rate limiting enzyme for glycogen synthesis

A

glycogen synthase

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5
Q

What is the rate limiting enzyme for glycogenolysis

A

glycogen phosphorylase

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6
Q

What is the rate limiting enzyme for HMP shunt

A

glucose 6 phosphate dehydrogenase (G6PD)

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7
Q

What is the rate limiting enzyme for urea cycle

A

carbamoyl phosphate synthetase

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8
Q

What is the rate limiting enzyme for Fatty acid synthesis

A

Acetyl Co-A carboxylase

ACC

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9
Q

What is the rate limiting enzyme for fatty acid oxidation (Beta oxidation)

A

carnitine acetyltransferase

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10
Q

What is the rate limiting enzyme for ketogenesis

A

HMG Co-A synthase

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11
Q

What is the rate limiting enzyme for cholesterol synthesis

A

HMG CoA reductase

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12
Q

What is the embden meyerhof pathway?

A

glycolysis

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13
Q

Glycolysis

Location

Net ATP

A

cystol

2

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14
Q

TCA cycle

Location

Net ATP

A

mitochondrial matrix

2 GTP

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15
Q

ETC

Location

Net ATP

A

inner mitochondrial membrane

32 (G3P shuttle)

34 (malate aspartae shuttle)

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16
Q

What is the fate of pyruvate during oxidation

Enzyme

Product

Function

A

Enzyme: pyruvate dehydrogenase

Product: acetyl coa

Function: ATP production and FA synthesis

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17
Q

What is the fate of pyruvate during reduction

Enzyme

Product

Function

A

Enzyme: lactate dehydrogenase

Product: lactate

Function: anaerobic glycolysis

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18
Q

What is the fate of pyruvate during carboxylation

Enzyme

Product

Function

A

What is the fate of pyruvate during

Enzyme: pyruvate carboxylase

Product: oxaloacetate

Function: gluconeogenesis; replenishes TCA

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19
Q

What is the fate of pyruvate during transamination

Enzyme

Product

Function

A

What is the fate of pyruvate during

Enzyme: alanine transaminase

Product: alanine

Function: amino acid synthesis

20
Q

What are the four different steps of gulconeogenesis from glycolysis?

A
  1. Pyruvate –> oxaloacetate

E: pyruvate carboxylase; uses 2 ATP –> 2 ADP

  1. Oxaloacetate –> PEP

E: PEP carboxykinase; uses 2 GTP –> ADP

  1. Fructose 1,6 bisphosphate –> Fructose 6 phosphate

E: (FBPase) Fructose Bisphophatase-1; uses H2O –> Pi

  1. G6P –> glucose

E: (G6Pase) Glucose-6-Phosphatase-1; uses H2O –> Pi

21
Q

What are the 2 places for gluconeogenesis?

A

Liver (90%)

Kidney (10%)

22
Q

Why does gluconeogenesis not occur in the muscle?

A

The muscle lacks the glucose 6 phosphotase enzyme, the last step to convert G6P to glucose.

23
Q

When does gluconeogenesis occur?

A

Occurs when there is low blood glucose.

24
Q

What inhibits the PEP carboxykinase enzyme?

A

Insulin

remember that carboxykinase is used in glycogenolysis and the whole point of the cycle is to increase blood glucose levels.

25
What is an allosteric inhibitor of PFK?
High [ATP] High [Citrate] - krebs cycle
26
What is an inhibitor of the enolase enzyme? Signficance in oral bacteria?
Fluoride Fluoride inhibits glycolysis in oral bacteria thus kills bacteria no production of acid --\> no caries!
27
During the glycogenesis reaction, where do the reactions occur?
There are two locations: Mitochondria: conversion of pyruvate to oxaloacetate Cytoplasma: everything else (oxaloacetate --\> glucose)
28
What is the structure of glycogen?
a polysaccharide of glucose; storage form of glucose made alpha 1,4 straight bond and alpha 1.6 branched bonds alpha 1,4 (most common) alpha 1,6 bonds (faster mobilization)
29
Where are most carbs stored in the body? What is the role of glycogen stored in liver? muscle?
Liver and muscle Liver maintains blood glucose levels Muscle provides quick energy, glucose during exerise
30
What is the enzyme of glycogenolysis? Function? What intermediates activate the enzyme?
Glycogen phsophorylase Phosphorylation to cut off end of glycogen branch to turn into active form Intermediates: cAMP, epinephrine, glucagon
31
Does glucagon activate the glycogen phosphrylase enzyme in both the liver and muscle?
No, glucagon cannot act on the muscle because it doesnt have a role in blood glucose regulation.
32
Glucagon acts on the liver to start glycogenolysis, what other system does it work on?
It activates the adenyly cyclase in adipocyte plasma membrane to raise cAMP which turns other enzymes on to breakdown triglycerols to FAs to be used as fuel.
33
What are the differnet numbers of carbons involved in CAC?
Oxaloacetate (4 C) Citrate (6C) isocitrate (6C) alpha ketoglutarate (5C) Succinyl CoA (4C) --\> Oxaloacetate (4C)
34
what is the most immediate available source of oxaloacetate?
aspartic acid note: OOA is interconvertable with aspartic acid
35
What is the only enzyme that is in both CAC and ETC?
succinate dehydrogenase
36
What inhibits the TCA and ETC cycle?
malonate the competitve inhibitor of succinate dehydrogenase.
37
During ETC, NADH is fed to which enzyme? FADH2?
NADH- Cytochrome Complex 1- NADH dehydrogenase complex FADH2- Cytochrome Complex 2 - succinate dehydrogenase complex
38
What is another name for the pentose phosphate pathway?
hexose monophosphate shunt (HM-shunt)
39
what is the stoichiochemistry of the pentose phosphate pathway?
glucose 6 phosphate + 2 NADP + H2O --\> Ribose 5 phosphate + 2 NADPH + 2H + CO2
40
What is the ultimate goal of PPP? Is ATP produced?
To produce ribose for nucleotide synthesis and NADPH for fatty acid and steroid synthesis. NO
41
NADPH produced from PPP can also help with what?
Helps rid of free radicals of erythrocytes and H2O2 (hydrogen peroxide).
42
What is the rate limiting step of PPP? What does this enzyme catalyze?
Glucose 6 phosphate dehydrogenase
43
What occurs when there's a deficiency of glucose 6 phosphate dehydrogenase?
hemolytic anemia due to a decrease in NADPH production thus increase in oxidizing agents in RBCs
44
What is the pathway of glycogenolysis? What is the pathway of glycogenolysis?
Gylocgenolysis Glycogen ---(glycogen phosphorylase)----\> glucose 1 phosphate --(phosphoglucomutase)---\> glucose 6 phosphate --(glucose 6 phosphatase)-----\> glucose
45
What is the pathway of glycogenesis? What is the pathway of glycogenesis?
Glucose --(hexokinase)----\> glucose 6 phosphate ----(phosphoglucomutase)----\> glucose 1 phosphate --(glycogen synthase)---\> glycogen

NBDE 1 (9 decks)

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