Proteins

Question 1

What are proteins used for?

Answer 1

They are the major structural materials of animal tissue

They are involved in the maintenance and regulation of life processes

Question 2

What are proteins made of?

Answer 2

Many amino acid molecules linked together by condensation reactions

Question 3

What do amino acids contain?

Answer 3

The amino (-NH2) and carboxyl (-COOH) functional groups

R is a side chain

H R O
I I II
N—C—C
I I I
H H OH

Question 4

How many common amino acids are used in the human body?

Answer 4

20

Question 5

Condensation of 2 amino acids

Answer 5

H R O H R O
I I II I I II
N—C—C + N—C—C
I I I I I I
H H OH H H OH

H R O H R O
I I II I I II
N—C—C—N—C—C
I I I I
H H H OH

Peptide/amid link

Question 6

What do the long-chain molecules form within proteins and how are they held together?

Answer 6

Spirals, sheets, or other complex shapes

They are held in these forms by intermolecular bonding between side chains of the the constituent amino acids

Question 7

What happens when proteins are heated?

Answer 7

The intermolecular bonds are broken, allowing the proteins to change shape (denature)

The denaturing of proteins in foods causes the texture to change when it is cooled

Question 8

What happens during digestion?

Answer 8

enzyme hydrolysis of protein produces amino acids

Question 9

What are essential amino acids?

Answer 9

Amino acids that the body cannot make that must be acquired from the diet for protein synthesis

Question 10

Are proteins polar or non-polar?

Answer 10

non-polar (not soluble in water)