Amino Acid Biosynthesis

Question 1

What cannot be synthesized by animals

Answer 1

Methionine
Threonine
Isoleucine
Lysine

Question 2

Biosynthesis of methionine

Answer 2

Only produced in plants and bacteria
When ingested, will react with ATP to form SAM
-methyl group carrier

Question 3

Pyruvate family

Answer 3

Valine and leucine cannot be synthesized by primates

Question 4

Glycine biosynthesis

Answer 4

Serine + tetrahydrofolate ->glycine+N-methylenetetrahydrofolate

Question 5

Cysteine biosynthesis

Answer 5

In plants and bacteria
Serine acetylated to O-acetylserine
Sulfur donor comes from PAPS

Question 6

Essential amino acid examples

Answer 6

Histidine - required in diet of infants (biosynthesis not sufficient)
~semi-essential
Arginine synthesized in urea cycle but is used there too, resulting in requirement in diet
Tyrosine and cysteine can alleviate requirement of phenylalanine and methionine

Question 7

Why can tyrosine and methionine alleviate requirements for phenylalanine and cysteine (respectively)

Answer 7

Phenylalanine can be converted to tyrosine

Methionine can be converted to cysteine