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MCAT Biology by me > Metabolism > Flashcards

Metabolism Flashcards

1
Q

Two pathways pyruvate can take

A

Acetyl CoA –> CAC

Gluconeogensis to G6P, but must cross into mitochondria first, to get converted into OAA –> malate –> shuttle to PEP b/c you can’t convert Pyruvate to PEP directly.

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2
Q

Net products of glycolysis

Which part of glycolysis in NADH made?

A

2 NADH and 2 ATP

NADH from the energy output portion

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3
Q

How fructose and galactose enter glycolysis

A

As an intermediate of the 6-C phase

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4
Q

When PPP meets glycolysis - intersection and how they’re related

A

G3P, Pyruvate doesn’t feed to PPP.

Intermediates from glycolysis like G3P, and F6P can become 4,5,7 C sugars, then become Ribose-5-P by transaldolase and transketolases.

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5
Q

Products created from PPP in oxidative and non-oxidative branches

A

oxidative - oxidize to reduce NAD+ to NADH

non-oxidative - ribose sugar like for nucleotides

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6
Q

Function of NADPH

A

cholesterol, FA

antioxidant formation (glutathione)

Bleach in WBC

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7
Q

In what types of tissues does PPP occur most frequently?

Give two examples

A

tissues that make lipids like liver and adipocytes

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8
Q

How PPP is regulated?

A

NADPH inhibiting the first step (negative feedback)

Irreversible

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9
Q

Glycogen linkage and branching linkage

Cost of glycogen synthesis

Cost of glycogenolysis

A

1,4-alpha linkage with branches at 1,6

Glycogen synthesis: one UTP, about one ATP

Glycogenolysis: ATP but instead Pi is enzymatically added to each alpha-1,4 bound glucose

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10
Q

Are the steps with large Gibbs energy difference in glycolysis and glycogenesis reversible? What are the usually accompanied by?

A

irreversible steps and accompanied by ATP or NADH

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11
Q

Requirement to be a substrate for gluconeogensis

Can lactic acid be a substrate for gluconeogensis

Can fatty acids work? Why or why not?

A

3-C

YUP

not fatty acids - cleaved 2C at a time
but glycerol can - 3C

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12
Q

how insulin and glucagon control the synthesis, storage, and release of glucose

A

insulin: decrease blood glucose level in the blood; anything that doesn’t create glucose as the final product like glycolysis and glycogenesis
glucagon: increase blood glucose level in the blood; any metabolic pathway that makes glucose as final product like gluconeogensis and glycogenolysis

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13
Q

Where do all the glucose pathways intersect at?

A

glucose-6-phosphate

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14
Q

Relationship between G6P and PPP

A

one way to PPP

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15
Q

beta-oxidation:

Main product
Number of carbons oxidized per oxidation and the byproducts

A

how fatty acids are broken down into acetly-coA to be released into the mitochondria

2 carbons are oxidized at a time, producing FADH2 and NADH

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16
Q

Products of ketogenesis

Where it occurs

When it occurs

Purpose of ketogenesis

A

To produce ketone bodies in the mitochondria

Occurs during extreme starvation - when there is an excess Acetyl-coA from too much beta-oxidation of fatty acids that cannot all go into CAC while there is low insulin to convert them back to fatty acids

To route the glucose to brain and blood and supply another form of energy to other organs

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17
Q

T/F all cells in the body can use ketone bodies for energy

A

False - RBC cannot use ketone bodies for energy

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18
Q

can ketone bodies be substrates for gluconeogensis

A

no - not 3C

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19
Q

What happens when there is excess acetyl-coA and absence of insulin

what happens when there is insulin?

A

Ketone body production

insulin - converts excess Acetyl coA into fatty acids

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20
Q

Metabolic pathways that happen few hours after you eat

A

to increase blood glucose

beta-oxidation, gluconeogensis, glycogenolysis, and ketongenesis in case of extreme starvation

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21
Q

special type of lipoprotein produced by the intestinal cells

pick up to destination; what liver does upon arrival

A

chylomicrons

intestine to liver; chylomicrons are repackaged in the liver to VLDL or HDL

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22
Q

VLDL vs HDL

A

VLDL - transport lipids from the liver to other parts of the body

HDL - picks up stray fatty acids and triglycerides from the periphery and brings them to the liver

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23
Q

hormonal vs. intestinal lipase

A

intestinal lipase: get fatty acids into the cell

hormonal lipase: get fatty acids out of the cell, hydrolyze triglycerides and release free fatty acids into the bloodstream which then undergo beta-oxidation

24
Q

protein anabolism (protein formation) is associated with what metabolic pathways?

A

glycolysis, glcogenesis, and lipid storage

25
Q

protein catabolism is associated with what metabolic pathways?

A

glconeogenesis, glcogenolsis, beta-oxidation, and ketone body synthesis

26
Q

what happens to the carbon chain once the nitrogen is removed from the protein?

A

fed as a substrate for various stages of the CAC

27
Q

glucose supply immediately after a meal

A

from intestines

use glucose and store excess glucose as glycogen and triglycerides

28
Q

Glucose supply few hours after a meal

How is this type of glucose supply compare as the ones coming directly from the intestines during and immediately after a meal?

A

liver - glycogenolysis, gluconeogenesis

nowhere near as abundant

29
Q

can glucose cross blood-brain-barrier?

A

yes

30
Q

RBC dependence on glucose

Does RBC have mitochondria? What metabolic pathway would it depend on?

A

depends entirely and only on glucose

has no mitochondria so it relies on fermentation in the cytosol

31
Q

insulin effect on liver, muscle, adipocytes, and tissues

A

promotion of glycolysis in all tissues

glycogenesis in liver and muscle

fatty acid synthesis in the liver and fatt acid storage in the adipocytes

32
Q

glucagon effect on liver, muscle, adipocytes, and all tissues

A

liver: gluconeogensis, glycogenolysis

beta-oxidation in almost all tissues

fatty acid release in adipocytes

muscle: glycogenolysis

33
Q

effect of epinephrine and cortisol

Types of stress
How they differ in increasing blood glucose

A

epinephrine: short-term stress response; glycogenolysis
cortisol: long-term stress; gluconeogensis

34
Q

what is the polarity of insulin, epinephrine, and glucagon

Thus, where is the receptor?

what about cortisol?

A

polar, hydrophilic

have receptors on the outside of the cell

cortisol is hydrophobic so it has receptors in the nucleus

35
Q

hydrolysis of phosphoanhydride bonds (in ATP)

Enthalpy?
Spontaneous?

A

spontaneous and exothermic; negative gibbs free energy

can provide the energy required for less energetically favorable reactions

36
Q

products of CAC one turn

A

3 NADH, 1 ATP, 1 FADH2

37
Q

one glucose produces how many turns of CAC

A

2

38
Q

What regulates CAC?

What happens when NADH builds up?

A

the amount of NAD+ available

NAD+ is generated by the oxidation of NADH by the ETC. no regeneration of NAD+ - no CAC; CAC is closely linked to ETC so it is aerobic

if NADH builds up, CAC slows down

39
Q

Once amino acids are deaminated in the liver, to what products can they be converted to and which metabolic pathway can it enter?

A

can be converted to pyruvic acid or acetyl-coA or it may enter the CAC at various stages

40
Q

What do fats must convert to in order to enter CAC?

A

acetyl coA

41
Q

ATP produced per NADH

A

2-3 ATP depending on whether or not ATP was spent to bring the NADH into the mitochondrial matrix

42
Q

ATP produced per FADH2

A

2 ATP

43
Q

Another function of cytochrome C

A

apoptosis in the event of cellular damage

44
Q

What happens if there is an excess NADH

A

CAC slows down

Shift the cell into anaerobic fermentation so that NADH can be converted to NAD+ by the conversion of pyruvate to lactate

45
Q

What are products of fermentation?

A

lactic acid or ethanoic acid

46
Q

net ATP of aerobic respiration

A

36 ATP

47
Q

NADH produced in acetyl-coA synthesis just before CAC

Where does this happen?

A

2

inside the mitochondria

48
Q

ATP, NADH, and FADH2 produced in CAC

A

1 ATP, 3 NADH, 1 FADH2 per cycle

49
Q

Where can acetyl coA go?

What can it become?

A

enter CAC to become citrate or enter glycolysis as an intermediate.

or become glycerol –> gluconeogensis possible

50
Q

Can brain use ketone bodies?
Can liver use ketone bodies?
To what can ketone bodies be converted to in order to be used as energy?

A

Brain yes
Liver no

Acetyl-coA

51
Q

What is beta-oxidation? Where does it take place?

A

chemical breakdown of fatty acids

mitochondria of liver cells

52
Q

How does NADH store energy?

A

in the high energy electrons of its hydrides

53
Q

What is the Gibbs free energy of hydrolysis of ATP?

A

negative Gibbs energy, spontaneous

54
Q

Permeability of mitochondrial membrane

A

Outer membrane, going into the intermemebrane space: permeable;

Inner membrane: everything except NADH can go in via facilitated diffusion. NADH requires 1 ATP to enter the inner membrane.

55
Q

What happens when there is no oxygen?

A

NADH can’t get recycled back to NAD+, CAC shuts down, so the cell has to resort to recycling NADH to NAD+ through fermentation

56
Q

Acetyl coA - how many C’s

A

2

MCAT Biology by me (16 decks)

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