Protein breakdown and urea formation

Question 1

What is growth

Answer 1

Synthesis - breakdown

Question 2

Why must excess proteins be broken down and excreted

Answer 2

Since there are no specific protein stores, and nitrogen is toxic if it accumulates

Question 3

How is nitrogen removed in mammals

Answer 3

its made into urea which is a non-toxic neutral compound, its then excreted in the urine

Question 4

what are the steps of nitrogen being transferred into urine

Answer 4

1. Transamination
2. Formation of ammonia
3. Formation of urea

Question 5

What is the general transaminase reaction

Answer 5

Amino acid A will donate its nitrogen to keto acid B making keto acid A and amino acid B

Question 6

What are some common alpha-keto acids

Answer 6

Alpha-ketogluterate, pyruvate and oxaloacetate

Question 7

What does alanine transaminase (ALT) do

Answer 7

Will cause a reaction between alanine and alpha-ketogluterate to form pyruvate and glutamate, where the forward reaction dominates

Question 8

What does aspartate transaminase (AST) do

Answer 8

Will cause a reaction between aspartate and alpha-ketogluterate to form oxaloacetate and glutamate, where the backwards reaction dominates

Question 9

What can alpha-keto gluterate, pyruvate and oxaloacetate be used for

Answer 9

Can be oxidised or converted to glucose

Question 10

What do high levels or AST and ALT in the blood mean

Answer 10

Its indicative of liver damage e.g. cirrhosis

Question 11

What do AST and ALT reactions require

Answer 11

Vitamin B6, since its active form pyridoxal phosphate