L19: Biological Reactions- amino acids & proteins

Question 1

What is the structure of amino acids?

Answer 1

1) Amino group
2) Carboxyl group
3) Side chain (R-group)

Question 2

Chemical Reactions

What is the result of cysteine oxidation?

Answer 2

2 chains of insulin connected by disulfide bonds

Question 3

Chemical Reactions

What is farnesylation?

Answer 3

Sticking a lipid (farnesyl) tail on to anchor proteins into membranes

Question 4

Chemical Reactions

What is glycosylation?

Answer 4

Decorating proteins with sugar chains

Question 5

Chemical Reactions

What are radical reactions?

Answer 5

Wild radicals react with other molecules to steal/share electrons

Question 6

Chemical Reactions

What is phosphorylation?

Answer 6

Adding a phosphate group from ATP using enzyme called kinase, that switches protein functions on/off

Question 7

Does pH go up or down when:
1) More base is added
2) More acid is added

Answer 7

1) Goes up
2) Goes down

Question 8

Describe the 4 stages of protein synthesis

1) Aminoacyl-tRNA binding
2) Peptide bond formation
3) Translocation
4) tRNA dissociation

Answer 8

1) tRNA carrying new amino acid enters ribosome at A site
2) New amino acid at A site attacks last amino acid on chain
3) Bond forms, ribosome shifts, old tRNA moves to E site
4) Old, empty tRNA leaves ribosome through E site

Question 9

What is the Maillard Reaction?

Answer 9

Chemical reaction between amino acids & sugars that gives out smells, flavours and colours in cooked food

Question 10

What are the negative side effects of the Maillard Reaction?

Answer 10

Makes AGEs (Advanced Glycation End-Products) which damages proteins & leads to cataracts

Question 11

What does it mean when Maillard Reaction is non-enzymatic?

Answer 11

Happens by heat, no enzyme help

Question 12

Describe the Maillard reaction in amino acids & sugars

Answer 12

1) Sugar (with carbonyl group) & amino group react = creating a N-substituted glycosylamine

2) Glycosylamine is unstable, rearranging itself into a ketosamine through Amadori rearrangement

3) Ketosamines break down into tiny compounds

Question 13

What is glycosylamine?

Answer 13

Molecule that happens when amino group & sugar react together, getting rid of the water molecule

Question 14

How does glycosylamine form?

Answer 14

Carbonyl group (C=O) of sugar is electrophilic
Amino group (-NH₂) is nucleophilic

SO

Amino group attacks carbonyl group of sugar to form Glycosylamine