Structures and pathways

Question 1

Draw glycolysis completely, all products, substrates, enzymes, GAPDH reaction (only this one) and the additional things in the reaction.

Answer 1

Refer to notes.

Question 2

Draw all the CAC, with inputs of water, NADH, FADH2, etc.

Answer 2

Refer to notes.

Question 3

Draw the PDC mechanism.

Answer 3

Refer to notes

Question 4

Draw B-oxidation.

Answer 4

Refer to notes.

Question 5

Draw the Aspartate-malate shuttle.

Answer 5

Refer to notes.

Question 6

Draw the generation of ketone bodies.

Answer 6

Refer to notes.

Question 7

Draw the urea cycle.

Answer 7

Refer to notes.

Question 8

Draw the pathway, from b-hydroxybutyrate for how the body uses ketone bodies.

Answer 8

Refer to notes.

Question 9

Draw the glucose alanine cycle.

Answer 9

Refer to notes

Question 10

Draw the urea cycle.

Answer 10

Refer to notes

Question 11

Draw alanine catabolism.

Answer 11

Refer to notes.

Question 12

Draw Aspargine catabolism

Answer 12

Refer to notes

Question 13

Draw glutamine catabolism

Answer 13

Refer to notes

Question 14

Draw Branched chain a-keto acid DH complex pathway.

Answer 14

Refer to notes (same as PDC tbh)

Question 15

Draw the PPP

Answer 15

Refer to notes

Question 16

Describe ammonia toxicity.

Answer 16

Two reasons this can happen:
1 - Can get this if the urea cycle is not working properly or
2 - inhale/ingest some form of ammonia.

Ammonia is soluble in the blood and can reach the brain.
Brain tries to get rid of ammonia.
A-keto (common scavenger), takes ammonia and is converted to glutamate by glutamate DH.
Glutamate functions as a NT so it needs to get rid of it and, it cant go in the blood, converted to glutamine using glutamine synthase.

Glutamine is placed in the blood and sent to the liver.

However, this is where the toxicity occurs:
- take lots of a-keto from CAC, gets blocked, not lots of ATP generation in brain

Also, since glutmate is a NT, can create havock, too much is a problem and too little is a problem
- without glutamate, can faint

Question 17

What are therapies for defects in the urea cycle?

Answer 17

1 - Defined diet with only essential amount of amino acids

2 - Benzoate or phenylacetate - react with glycine and glutamine (respectively) and get excreted in the urine - causes these to be low in body so ammonia levels go down due to synthesis

Question 18

Which amino acids are branched chain?

Draw R.

Answer 18

Valine (1-3 bis), leucine (2,1,3), isoleucine (1,2,3)

Question 19

What is a glucogenic amino acid?

Answer 19

Glucogenic aa - catabolized to produce something like pyruvate, oxaloacetate, succinyl-CoA, which can be converted to glucose by neoglucogenesis.

Question 20

What is a ketogenic amino acids?

Answer 20

Amino acids that make acetyl-CoA when catabolized, converted to ketone bodies.

Question 21

Describe alkaptonuria.
What process is defective?
What enzyme is defective?
What are the symptoms?

Answer 21

Process: Tyrosine degradation
Enzyme: homogentisate-1,2-dioxygenase
Symptoms: excrete homogentisate

Question 22

Describe phenylketouria.
What process is defective?
What enzyme is defective?
What are the symptoms?

Answer 22

Process: Conversion of phenylalanine to tyrosine
Enzyme: phenylalanine hydroxylase
Symptom: Excrete Phenylalanine

Question 23

Describe maple syrup urine disease.
What process is defective?
What enzyme is defective?
What are the symptoms?
Treatment?

Answer 23

Process/enzyme: Branched chain keto-acid DHC is defective

Symptoms: brain issues, muscle fatigue, urine smells like maple syrup, branched-chain keto acids accumulate in urine

Treatment: carbs and fats as major dietary source, only small amount of protein for growth
- remove branched chain amino acids from diet

Question 24

Describe MMA.
What process is defective?
What enzyme is defective?
What are the symptoms?
Treatment?

Answer 24

Process: Odd-chain fatty acid catabolism (convert propionyl-A- succinyl-CoA)

Enzyme: Methyl-malonyl-Coa mutase

Symptoms: accumulation of methyl-malonyl-CoA
- fatal, vomiting convulsions, etc.

Treatment: reduce protein intake, remove isoleucine and leucine (branched chain aa) and odd chain fatty acids.

Question 25

Draw odd-chain fatty acid catabolism

Answer 25

Refer to notes.

Question 26

Draw the cori cycle.

Answer 26

Refer to notes.

Question 27

Why does insulin increase glycolysis?

Answer 27

Indicates there is lots of glucose circulating in the body, makes glycogen first but the rest is converted to acetyl-CoA to be stored as fat.

Question 28

Describe alcohol toxicity.

Answer 28

When drinking, two enzymes used to catabolized alcohol:
Alcohol DH
Aldehyde DH
Get acetate production.
Both produce NADH, this blocks PDC, CAC and the GAPDH reaction and B-oxidation.
Thus, get accumulation of fat in liver –> hyperlipidemia.

CAC blocked leads to decrease in oxaloacetate and thus inhibition of gluconeogenesis –> hypoglycemia

Excess NADH accelerates lactate DH to produce lactic acid leading to hyperlactiacidemia.
Accumulation of lactic acid and acetic acid from circulating ketone bodies causes liver acidosis.

Question 29

Describe the effect of leptin on food intake and energy expenditure.

Answer 29

Fat cells produce leptin after fat deposition

Leptin goes into blood to hypothalamus and:
1 - Leads to blocking of synthesis of neuropeptide Y.
2 - Through NT signal via sympathetic neurons, communicates from pituitary to fat tissues

• sends norepinephrine, binds to B3-adrenergic receptor, leads to PKA activation. PKA phosphorylates TF, transcribes UCP - thermogenin
• UCP goes to mt when FA catabolized and leads to generation of heat