Protein Structure and Function

Question 1

Properties of Alanine (Ala)

Answer 1

Aliphatic R group
Hydrophobic R group
Participates in hydrophobic interactions

Question 2

Properties of Valine (Val)

Answer 2

Aliphatic R group
Highly hydrophobic R group
Participates in hydrophobic interactions

Question 3

Properties of Leucine (Leu)

Answer 3

Aliphatic R group
Highly hydrophobic R group
Participates in hydrophobic reactions

Question 4

Properties of Isoleucine (Ile)

Answer 4

Aliphatic R group
Highly hydrophobic R group
Participates in hydrophobic reactions
Similar to leucine but has a different branching point
Has 2 chiral carbons

Question 5

Properties of Phenylalanine (Phe)

Answer 5

Aromatic R group
Abs UV light at 280 nm
Highly hydrophobic R group
Participates in hydrophobic interactions

Question 6

Properties of Tryptophan (Trp)

Answer 6

Aromatic R group
Heterocyclic 
Abs UV light at 280 nm
Hydrophobic, bulky
Participates in hydrophobic interactions
Forms H bonds - donor

Question 7

Properties of Methionine (Met)

Answer 7

Hydrophobic
Participates in hydrophobic interactions
Sulfer containing side group (thioether)
Forms H bonds - acceptor

Question 8

Properties of Proline (Pro)

Answer 8

Aliphatic side chain with a distinctive cyclic structure
Weakly hydrophobic
Participates in hydrophobic interactions

Question 9

Properties of Glycine (Gly)

Answer 9

Achiral
Weakly polar
Very small and flexible

Question 10

Properties of Serine (Ser)

Answer 10

Polar, uncharged
H donor
can be phosphorylated

Question 11

Properties of Threonine (Thr)

Answer 11

Polar, uncharged
H bond donor
can be phosphorylated

Question 12

Properties of Tyrosine (Tyr)

Answer 12

Weakly polar, uncharged
Aromatic R group
Can participate in hydrophobic interactions
H bond donor
can be phosphorylated

Question 13

Properties of Cysteine (Cys)

Answer 13

Polar, uncharged
Sulfer side group (sulfhydryl)
Can form H bonds
Forms disulphide bridges with other cysteines

Question 14

Properties of Asparagine (Asn)

Answer 14

Amide side chain
Polar, uncharged
H bond donor and acceptor

Question 15

Properties of Glutamine (Gln)

Answer 15

Amide side chain
Polar, uncharged
H bond donor and acceptor

Question 16

Properties of Histidine (His)

Answer 16

Can be acidic or basic at neutral pH
Aromatic
Polar, charged/uncharged
Proton donor or acceptor

Question 17

Properties of Aspartate (Asp)

Answer 17

Negatively charged R group at neutral pH
Acidic amino acid
Very polar
H bond acceptor
Called aspartic acid at pH 1

Question 18

Properties of Glutamate (Glu)

Answer 18

Negatively charged R group at neutral pH
Acidic amino acid
Very polar
H bond acceptor
Called glutamic acid at pH 1

Question 19

Properties of Lysine (Lys)

Answer 19

Positively charged R group at neutral pH
Basic amino acid
H bond donor
Very polar

Question 20

Properties of Arginine (Arg)

Answer 20

Positively charged R group at neutral pH
Guano group
Basic amino acid
Never deprotonated under physiological conditions
Very polar
H bond donor

Question 21

Primary level of protein structure

Answer 21

Sequence of amino acids joined by peptide bonds

Question 22

Secondary level of protein structure

Answer 22

Local folding of the polypeptide backbone into sub-structures

Question 23

Tertiary level of protein structure

Answer 23

Arrangement of all atoms and sub-structures of a single, folded polypeptide in space

Question 24

Quaternary level of protein structure

Answer 24

Association of two or more distinct folded polypeptides