Metabolism

Question 1

Two pathways pyruvate can take

Answer 1

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.

Question 2

Net products of glycolysis

Which part of glycolysis in NADH made?

Answer 2

2 NADH and 2 ATP

NADH from the energy output portion

Question 3

How fructose and galactose enter glycolysis

Answer 3

As an intermediate of the 6-C phase

Question 4

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

Answer 4

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.

Question 5

Products created from PPP in oxidative and non-oxidative branches

Answer 5

oxidative - oxidize to reduce NAD+ to NADH

non-oxidative - ribose sugar like for nucleotides

Question 6

Function of NADPH

Answer 6

cholesterol, FA

antioxidant formation (glutathione)

Bleach in WBC

Question 7

In what types of tissues does PPP occur most frequently?

Give two examples

Answer 7

tissues that make lipids like liver and adipocytes

Question 8

How PPP is regulated?

Answer 8

NADPH inhibiting the first step (negative feedback)

Irreversible

Question 9

Glycogen linkage and branching linkage

Cost of glycogen synthesis

Cost of glycogenolysis

Answer 9

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

Question 10

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

Answer 10

irreversible steps and accompanied by ATP or NADH

Question 11

Requirement to be a substrate for gluconeogensis

Can lactic acid be a substrate for gluconeogensis

Can fatty acids work? Why or why not?

Answer 11

3-C

YUP

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

Question 12

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

Answer 12

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

Question 13

Where do all the glucose pathways intersect at?

Answer 13

glucose-6-phosphate

Question 14

Relationship between G6P and PPP

Answer 14

one way to PPP

Question 15

beta-oxidation:

Main product
Number of carbons oxidized per oxidation and the byproducts

Answer 15

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

Question 16

Products of ketogenesis

Where it occurs

When it occurs

Purpose of ketogenesis

Answer 16

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

Question 17

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

Answer 17

False - RBC cannot use ketone bodies for energy

Question 18

can ketone bodies be substrates for gluconeogensis

Answer 18

no - not 3C

Question 19

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

what happens when there is insulin?

Answer 19

Ketone body production

insulin - converts excess Acetyl coA into fatty acids

Question 20

Metabolic pathways that happen few hours after you eat

Answer 20

to increase blood glucose

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

Question 21

special type of lipoprotein produced by the intestinal cells

pick up to destination; what liver does upon arrival

Answer 21

chylomicrons

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

Question 22

VLDL vs HDL

Answer 22

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

Question 23

hormonal vs. intestinal lipase

Answer 23

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

Question 24

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

Answer 24

glycolysis, glcogenesis, and lipid storage

Question 25

protein catabolism is associated with what metabolic pathways?

Answer 25

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

Question 26

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

Answer 26

fed as a substrate for various stages of the CAC

Question 27

glucose supply immediately after a meal

Answer 27

from intestines use glucose and store excess glucose as glycogen and triglycerides

Question 28

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?

Answer 28

liver - glycogenolysis, gluconeogenesis nowhere near as abundant

Question 29

can glucose cross blood-brain-barrier?

Answer 29

yes

Question 30

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

Answer 30

depends entirely and only on glucose has no mitochondria so it relies on fermentation in the cytosol

Question 31

insulin effect on liver, muscle, adipocytes, and tissues

Answer 31

promotion of glycolysis in all tissues glycogenesis in liver and muscle fatty acid synthesis in the liver and fatt acid storage in the adipocytes

Question 32

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

Answer 32

liver: gluconeogensis, glycogenolysis beta-oxidation in almost all tissues fatty acid release in adipocytes muscle: glycogenolysis

Question 33

effect of epinephrine and cortisol Types of stress How they differ in increasing blood glucose

Answer 33

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

Question 34

what is the polarity of insulin, epinephrine, and glucagon Thus, where is the receptor? what about cortisol?

Answer 34

polar, hydrophilic have receptors on the outside of the cell cortisol is hydrophobic so it has receptors in the nucleus

Question 35

hydrolysis of phosphoanhydride bonds (in ATP) Enthalpy? Spontaneous?

Answer 35

spontaneous and exothermic; negative gibbs free energy can provide the energy required for less energetically favorable reactions

Question 36

products of CAC one turn

Answer 36

3 NADH, 1 ATP, 1 FADH2

Question 37

one glucose produces how many turns of CAC

Answer 37

2

Question 38

What regulates CAC? What happens when NADH builds up?

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

acetyl coA

Question 41

ATP produced per NADH

Answer 41

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

Question 42

ATP produced per FADH2

Answer 42

2 ATP

Question 43

Another function of cytochrome C

Answer 43

apoptosis in the event of cellular damage

Question 44

What happens if there is an excess NADH

Answer 44

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

Question 45

What are products of fermentation?

Answer 45

lactic acid or ethanoic acid

Question 46

net ATP of aerobic respiration

Answer 46

36 ATP

Question 47

#NADH produced in acetyl-coA synthesis just before CAC Where does this happen?

Answer 47

2 inside the mitochondria

Question 48

ATP, NADH, and FADH2 produced in CAC

Answer 48

1 ATP, 3 NADH, 1 FADH2 per cycle

Question 49

Where can acetyl coA go? What can it become?

Answer 49

enter CAC to become citrate or enter glycolysis as an intermediate. or become glycerol --> gluconeogensis possible

Question 50

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?

Answer 50

Brain yes Liver no Acetyl-coA

Question 51

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

Answer 51

chemical breakdown of fatty acids mitochondria of liver cells

Question 52

How does NADH store energy?

Answer 52

in the high energy electrons of its hydrides

Question 53

What is the Gibbs free energy of hydrolysis of ATP?

Answer 53

negative Gibbs energy, spontaneous

Question 54

Permeability of mitochondrial membrane

Answer 54

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.

Question 55

What happens when there is no oxygen?

Answer 55

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

Question 56

Acetyl coA - how many C's

Answer 56

2