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MCAT > Biochemistry: C5 - Pathways > Flashcards

Biochemistry: C5 - Pathways Flashcards

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MCAT flashcards
1
Q

Gluconeogenesis is when the ___ is depleted of _____ and the body is deprived sources of ___.

A

liver, glycogen and glucose, glucose

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2
Q

What are 3 main simple sugars?

A

glucose, fructose, and galactose

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3
Q

How do you make sucrose?

A

fructose + glucose

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4
Q

How do you make maltose?

A

glucose + glucose

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5
Q

How do you make lactose?

A

galactose + glucose

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6
Q

Write the order from the smallest to largest structure.

A

monosac -> disach ->oligosac -> polysac

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7
Q

Another name for polysac

A

polymer

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8
Q

Linkage btwn sugars and the type of linkage

A

covalent, glycosidic linkage

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9
Q

name the sugars found in animals and their function

A

Glycogen: storage
chitin: structural

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10
Q

name the sugars found in plants and their function

A

starch: storage
cellulose: structural

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11
Q

what are the structures that make up cellulose?

A

cellobiose

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12
Q

the hydrolysis of polysac/glycosidic linkage is…

A

thermodynamically favorable

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13
Q

enzyme to break different bonds are…

A

specific

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14
Q

What linkage cannot be digested by mammals? What is the exception?

A

Beta linkage. Babies –> ability to digest beta linked lactose
Cows have bacteria in their rumen that helps them digest the Beta links

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15
Q

What are the 4 steps of cellular respiration?

A
  1. Glycolysis
  2. pyruvate dehydrogenase
  3. Krebs Cycle
  4. Electron Transport and Oxidative Phosphorylation
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16
Q

List the location, start and end product, net products off…Glycolysis

A
  • cytoplasm
  • glucose –> 2 pyruvate molecules
  • 2 ATP and 2 NADH
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17
Q

List the location, start and end product, net products off…pyruvate dehydrogenase

A
  • matrix
  • pyruvate –> acetyl CoA
  • 1 NADH (per pyruvate)
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18
Q

List the location, start and end product, net products off…Krebs cycle

A
  • matrix
  • acetyl CoA –> OOA
  • 3 NADH, 1 FADHs, 1 GTP (1 pyruvate)
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19
Q

List the location, start and end product, net products off…ETC and oxidative phosphorylation

A
  • inner and inter membrane

- NAD+, FADH and ATP

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20
Q

For every NADH oxidized to NAD+, how many protons are produce and how many ATP does that translate to?

A

NAD+ release 10 protons, and that produces 2.5 ATP is produced.

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21
Q

For every FADH2 oxidized to NADH, how many protons are produce and how many ATP does that translate to?

A

6 protons and 1.5 ATP is produced.

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22
Q

What transports the electron carriers from glycolysis to ubiquinone?

A

Glycerol phosphate shuttle

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23
Q

Glycolysis

A

Glyc- sugar
Lysis- splitting

splitting of sugar

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24
Q

pyruvate dehydrogenase

A

dehydrogenase -> means removal of hydrogen –> or gain of oxygen –> oxidation –> oxidative decarboxylation
This means the pyruvate (3C) decarboxylated to form Acetyl –> acetyl CoA (2C)

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25
Q

How many carbons are there in each structure?

A 
Glucose: 6
OAA: 4
Pyruvate 3
Acetyl CoA: 2: 
citrate: 6
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26
Q

When and how is citrate made?

A
  • krebs cycle

- OAA + Acetyla CoA

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27
Q

Net products of Krebs w/ 1 pyruvate molecule

A

3 NADH, 1 GTP, 2 CO2, 1 FADH

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28
Q

What happens to glucose when it enter glycolysis and why? options: oxidization or reduction?

A

glucose is oxidized because when we break the molecule, we release 4 hydrogen molecules to NAD+ to produce NADH

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29
Q

Krebs Cycyle

A

also known as citric acid or tricarboxylic acid

Basically combining OAA to acetyl CoA to make OAA again. Why is this done? oxidative decarboxylation is a favorable rxn.

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30
Q

oxidative decarboxylation

and example

A

is a favorable reaction that drives less favorable rxns

- fatty acid synthesis, gluconeogenesis

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31
Q

What two process use oxygen indirectly?

A

Pyruvate dehydrogenase and Kreb cycle bc they use the by product of the electron transport chain, which requires O2

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32
Q

What is the important of O2?

A

O2 is the final electron acceptor in the ETC. It gets rid of low energy electrons and gets rid of Hydrogen atoms.

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33
Q

what oxidizes NADH and FADH2?

A

ETC

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34
Q

2 goals of ETC and oxidative phos?

A
  1. oxidize NADH and FADH2 from glycolysis, PDC and Krebs

2. store energy in the form of ATP

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35
Q

Where is there high and low concent of H+ and what si the pH?

A

Intermembrane: High [H+] -> low pH -> acidic
Matrix: Low [H+] -> high pH -> basic

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36
Q

How many complexes are there in the ETC?

A

5 and 1 ATP synthase

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37
Q

which layer of the mitochondria bilipid layer is impermeable?

A

inner mitochondrial matrix

38
Q

which layer of the mitochondria bilipid layer has the complexes?

A

inner

39
Q

what produces energy to for ATP?

A

H+ pumping from inner mm to matrix provides energy to phosphorylate ADP

40
Q

what produces energy to pump H+ to intermembrane space?

A

the energy from NADH and FADH2 getting oxidized as they travel through the ETC

41
Q

what is the committed step and why is it called that?

A

The time when phosphofructosekinase adds a phospphate group to F6P, producing F1,6bP.
While F6P can be used else where in the body, F1,6bP can only serve in glycolysis and so it committed to this step.

42
Q

What does PFK stand for and do?

A

Phosphofructosekinase is part of glycolysis. It is responsible for adding a P group to F6P.

43
Q

fermentation definition

A

the process that takes place when there is no oxygen present. No oxygen means no means of oxidizing NADH to NAD+ to start glycolysis. Fermentation (formation of ethanol or alcohol) modifies pyruvate to become electron carriers.

44
Q

yeast uses what fermentation process?

A

reduction of pyruvate to form ethanol (yeast)

45
Q

muscle uses what fermentation process?

A

reduction of pyruvate to form lactate (humans)

46
Q

Can yeast and humans carry on anaerobically?

A

no because high concentrations of ethanol or lactate are poisonous.

47
Q

what are cofactors?

A

non-protein compounds that help enzymes in their biological activity

48
Q

Prosthetic group?

A

a cofactor that is tightly bound to the enzyme

49
Q

Why do prokaryotes produce more ATP than euk?

A

prokaryotes do not have membrane bound organelles, so their mitochondria is open. This allows them to save energy when having to transport electron carriers.

50
Q

How is oxidative phosphorylation possible in prokaryotes?

A

they use their cell membrane to create proton gradient

51
Q

Name the order of complexes

A

NADH dehydrogenase (coenzyme Q reductase), ubiquinone (coenzyme Q), Cytochrome C reductase, Cytochrome C, Cytochrome C oxidase, ATP synthase

52
Q

What are 2 small mobile electron carriers?

A

coenzyme Q and cytochrome C

53
Q

Name the 3 cytochromes

A

NADH dehydrogenase (coenzyme Q reductase), Cytochrome C reductase, and Cytochrome C oxidase

54
Q

what do the large cytochrome proteins do?

A

pump protons across matrix and into the intermembrane space

55
Q

Enzymes involved in glycolysis

A

Hexokinase/glucokinase, Phosphofructokinase-1 (PFK-1), and Pyruvate kinase

56
Q

enzymes in fermentation

A

lactate dehydrogenase

57
Q

enzymes in pryuvate –> acetyl-CoA

A

Pyruvate dehydrogenase

58
Q

enzymes in Krebs

A

citrate synthase, isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase

59
Q

enzymes of ETC/Oxidative phosphorylation

A

Glycerol phosphate shuttle

60
Q

Function of Glycerol phosphate shuttle

A

transports NADH electrons from glycolysis to ubiquinone

61
Q

citrate synthase

A

krebs

combines OAA with Acetyl CoA

62
Q

isocitrate dehydrogenase

A

krebs

removal of CO2; isocitrate → alpha-ketoglutarate

63
Q

alpha-ketoglutarate dehydrogenase

A

krebs

removal of CO2; alpha-ketoglutarate → succinyl-CoA

64
Q

Pyruvate dehydrogenase

A

aka oxidative decarboxylation. 3C pyruvate molecule → 2C + CO2 + NADH

65
Q

lactate dehydrogenase

A

fermentation

reduces pyruvate to lactic acid, and there by converting NADH → NAD+.

66
Q

Pyruvate kinase

A

irreversible enzyme, removes phosphate from PEP to ADP: pyruvate(P) → pyruvate + ATP (per 1 pyruvate molecule).

67
Q

Phosphofructokinase-1 (PFK-1)

A

rate limiting enzyme, irreversible enzyme. Add phosphate to the other end of the isomerized F6P → F1,6bP

68
Q

Hexokinase/glucokinase (if in liver)

A

irreversible enzyme. First step in glycolysis; adds phosphate from ATP, and adds it to the glucose. Glucose → G6P → isomerized → F6P.

69
Q

Gluconeogenesis

A

is when the liver is depleted of glycogen and glucose and the body is deprived sources of glucose.

  • that converts non-carbohydrates precursor molecules into glucose.
  • reverse glycolysis
70
Q

____ cannot take place in gluconeogenesis.

A

Acetyl-CoA

71
Q

Enzymes involved in gluconeogensis`

A

Pyruvate carboxylase, PEP carboxykinase, Fructose 1,6 bisphosphatase, Glucose 6 phosphatase,

72
Q

Pyruvate carboxylase

A

adds CO2 to pyruvate → OAA

73
Q

PEP carboxykinase

A

oxidative decarboxylation and phosphorylation of OAA → PEP (5C)

74
Q

Fructose 1,6 bisphosphatase

A

removal of phosphate group F1,6bP → F6P

75
Q

Glucose 6 phosphatase

A

removal of phosphate group - G6P → glucose

Glucose 6 phosphatase is charged. In order to cross cell membrane and leave liver, it must be dephosphorylated.

76
Q

Futile cycling

A

when both pathways are running at the same time. To prevent this, both roles need to be highly regulated

77
Q

Reciprocal control

A

when same molecule regulates two enzymes in opposite ways

78
Q

glycolysis is run by what enzyme?

A

Phosphofructokinase (PFK)

79
Q

gluconeogenesis is run by what enzyme?

A

Fructose-1,6-bisphosphatase (F1-6BPase)

80
Q

High AMP?

A

→ activate PFK and inhibits F1-6BPase (low E → high E)

81
Q

presence of Insulin ______ F-2,6-bP

why?

A

activates
When we are eating, we usually ingest carbs (sugars). The presence of sugars activates the pancreas to release insulin. Insulin promotes the cells to take in the sugars (glucose) from the blood and store it as enegry (via glycolysis).

82
Q

presence of Glucagon _______ F-2,6-bP

why?

A

inhibits
When glucose levels are down, it means we lack sources to make energy (ATP). Gluconeogenesis is a process that allows the body to create glucose from non-carb intermediates. To let this process happen, glucagon breaks down F2,6bP. Turns off PFK → no glycolysis. And activates fructose-1,6-bisphosphatase → gluconeogenesis. Now, glucose is made for energy (ATP).

83
Q

what synthesizes F2,6-bP?

A

insulin

84
Q

what breaks down F2,6bP?

A

glucagon (pancreas)

85
Q

Increased concentrations of intermediates in a pathway _____ the activity of the pathway

A

decrease

86
Q

What does insulin do?

A

active the formation of F2, 6-bP

87
Q

What does F2, 6-bP do?

A

turns on PFK –> gylcolysis

turns off fruc-1,6-bisPhase –> turns off gluconeogenesis

88
Q

What do insulin and glucagon do?

A

they control the concentration of fructose-2,6-bisphosphate

89
Q

What does PFK stand for?

A

phosphofructokinase

90
Q

what does F1-1,6-Bpase stand for?

A

fructose-1,6-bisphosphate

MCAT (4 decks)

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