Processing Of Protein Week 5

Question 0

What is tyrosine used for?

Answer 0

Tyrosine is in dopamine, noradrenalin and adrenaline.

Question 1

What amino acid is in haem?

Answer 1

Glycine is in haem.

Question 2

What amino acid is found in serotonin?

Answer 2

Tryptophan is found in serotonin.

Question 3

What amino acid is found in histamine?

Answer 3

Histidine

Question 4

What amino acids are used in creatine ?

Answer 4

Glycine and arginine are used in creatine.

Question 5

What is nitrogen used for in the body?

Answer 5

Nitrogen is used for energy or energy storage compounds if not synthesis. However the amino acid groups must be removed and nitrogen secreted safely from the protein

Question 6

There are 3 steps to ammonia disposal, what are they?

Answer 6

The 3 steps are transamination, deamination and urea synthesis.

Question 7

What is transamination?

Answer 7

Transamination is the transfer of a into group to alpha-keto glutamate forming glutamate. This require pyridoxal phosphate and transaminase.

Question 8

What is deamination?

Answer 8

Deamination is the release of ammonia from glutamate (mainly in liver). This reaction requires glutamate dehydrogenase. Uses NADP produces NADPH.

Question 9

What is pyridoxal phosphate?

Answer 9

Pyridoxal phosphate is the active form of vitamin B6. It is required for the transamination and non essential synthesis of amino acids –> to make neurotransmitters, haem and for energy and lipid synthesis.

Question 10

A lack of pyridoxine phosphate leads to what?

Answer 10

Lack of vitamin b6 leads to anaemia (no haem), neurological symptoms, and poor growth and immune response.

Question 11

Where does the urea cycle take place?

Answer 11

The urea cycle takes place partially in mitochondria and partially in the cytosol.

Question 12

What is the controlling step in the urea cycle?

Answer 12

Carbomoyl phosphate synthetase is the key controlling step. Carbomoyl phosphate is formed from ammonia and bicarbonate. Requires ATP.

Question 13

How is carbomoyl phosphate synthase 1 activated?

Answer 13

Carbomoyl phosphate synthase 1 is activated by N-acetyl glutamate which is formed when glutamate levels are high. (Signalling high levels of protein catabolism).

Question 14

How is the urea cycle activated?

Answer 14

By high amino acid levels.

Question 15

What happens in the cytosol of the liver in the urea cycle?

Answer 15

In the cytosol a second amino acid is added from aspartate.

This forms arginine allowing for urea to be released.

Question 16

What is Uric acid?

Answer 16

Uric acid is derived from purine nucleotides rather than protein. Excess Uric acid in the blood (hyperuricaemia) can lead to deposition of sodium urate crystals in the kidneys and in the joints (gout).

Question 17

Why does hyperuricaemia occur?

Answer 17

Hyperuricaemia is due to over production of urate or poor excretion via the kidneys.

High purine foods (red meat, yeast) should be avoided

Question 18

What happens to the carbon skeletons left after nitrogen disposal?

Answer 18

The carbon skeletons are fed into Krebs cycle (ATP synthesis), glucose synthesis through gluconeogenesis

Question 19

Which amino acids can’t be made into glucose?

Answer 19

Lysine and Leucine are solely ketogenic so can only be made into acetyl CoA or ketone bodies.

Question 20

What is gluconeogenesis?

Answer 20

Gluconeogensis is glucose synthesis from non carbon intermediates during fasting or exercise.

Question 21

Where does gluconeogenesis mainly take place?

Answer 21

Gluconeogenesis mainly takes place in thy cytosol of liver and kidney.

Question 22

How long do glycogen stores last?

Answer 22

Glycogen stores last about 18 hours

Question 23

What are the 3 main sources used for gluconeogenesis?

Answer 23

1. Keto acids from amino acids
2. Lactate from anaerobic glycolysis
3. Glycerol from triacylglycerol breakdown.

Question 24

There are 3 steps to the the reversal of glycolysis. What are they?

Answer 24

1. Pyruvate to phosphoenolpyruvate. (Requires several stages)
2. Fructose 1,6 biphosphage to fructose 6 phosphate (via fructose 1,6 bisphosphatase)
3. Glucose 6 phosphate to glucose. (Via glucose 6 phosphatase). Requires 6ATO.

Question 25

How are gluconeogensis and glycolysis regulated?

Answer 25

Gluconeogenesis and glycolysis are reciprocally regulated.

Question 26

How is the conversion of fructose 1,6 phosphate to glucose 6 phosphate controlled?

Answer 26

There is allosteric inhibition by AMP, activated by citrate, activated by glucagon and inhibited by insulin.

The reverse applies for glycolysis.

Question 27

How is the conversion of pyruvate to phosphoenolpyruvate controlled?

Answer 27

Pyruvate to PEP is activated by acetyl CoA and inhibited by ADP.

the reverse applies for glycolysis.

Question 28

What is the Cori cycle?

Answer 28

The cori cycle is where the liver converts the lactate from respiring muscle back to glucose.

Question 29

What is the glucose alanine cycle?

Answer 29

The glucose alanine cycle maintains transamination in peripheral tissue
Alanine in the liver is a used to produce glucose to be used in peripheral tissue which produces alanine to restart the process

Question 30

What does alcohol do to make you hungry?

Answer 30

Ethanol metabolism produces large amounts of NADH. This cause conversion of pyruvate and alanine to lactate. This stops the conversion of glycerol to glycerolaldehyde 3 phosphate. Stops gluconeogensis, less glucose so hunger.