Amino acids, Peptides, and Proteins

Question 1

Amino acid general structure

Answer 1

• hydrogen
• central alpha carbon
• amino acid group (NH3+)
• carboxyl group (COO-)

Question 2

How do the 20 amino acids differentiate from each other?

Answer 2

• by their side chain (r) groups

Question 3

Stereoisomers

Answer 3

• L and D isomers (proteins are made almost exclusively from L

Question 4

Text groups of amino acids:

Answer 4

• non-polar
• aromatic
• polar, uncharged
• polar, positively charged
• polar, negatively charged

Question 5

The 20 amino acids include:

Answer 5

• Glycine
• Alanine
• Valine
• Leucine
• Isoleucine
• Proline
• Methionine
• Tyrosine
• Phenylalanine
• Tryptophan
• Cysteine
• Asparagine
• Glutamine
• Serine
• Threonine
• Lysine
• Arginine
• Histidine
• Aspartate
• Glutamate

Question 6

Glycine

Answer 6

• Gly
• G
• Only amino acid who doesn’t have a chiral center
• Non polar

Question 7

Alanine

Answer 7

• Ala
• A
• single hydrocarbon side chain
• Non polar

Question 8

Valine

Answer 8

• Val
• V
• 2 hydrocarbon side chains
• non polar

Question 9

Leucine

Answer 9

• Leu
• L
• 5 hydrocarbon side chains (one extended on the third carbon)
• non polar

Question 10

Isoleucine

Answer 10

• Ile
• I
• 5 hydrocarbon side chains
  (one extended on the second carbon)
• non polar

Question 11

Proline

Answer 11

• Pro
• P
• only molecule that has a ring directly off central carbon that is closed
• form tight turns
• non polar

Question 12

Methionine

Answer 12

• Met
• M
• Sulfur in the middle of side chain
• non polar

Question 13

Tyrosine

Answer 13

• Tyr
• Y
• Has ring off side chain with an OH group
• aromatic

Question 14

Phenylalanine

Answer 14

• Phe
• F
• ring off side chain
• aromatic

Question 15

Tryptophan

Answer 15

• Trp
• W
• two rings off side chain
• aromatic

Question 16

Cysteine

Answer 16

• Cys
• C
• Only other amino that has sulfur
• polar uncharged

Question 17

Asparagine

Answer 17

• Asn
• N
• double bonded O off side chain
• polar uncharged

Question 18

Glutamine

Answer 18

• Gln
• Q
• double bonded O off side chain of two carbons
• polar uncharged

Question 19

Serine

Answer 19

• Ser
• S
• OH bonded off side chain
• polar uncharged

Question 20

Threonine

Answer 20

• Thr
• T
• OH bonded off side chain with extra carbon
• polar uncharged

Question 21

Lysine

Answer 21

• Lys
• K
• Ends in positive charge NH3+
• polar, positive

Question 22

Arginine

Answer 22

• Arg
• R
• Ends in positive charge, splits like a Y
• polar positive

Question 23

Histidine

Answer 23

• His
• H
• unique side chain of 5
• polar positive

Question 24

Aspartate

Answer 24

• Asp
• D
• negatively charged, ends in two O’s branched
• polar negative

Question 25

Glutamate

Answer 25

• Glu
• E
• negatively charged, ends in two O’s with 2 carbon chain
• polar negative

Question 26

Non-polar group

Answer 26

• mainly hydrocarbon side chains
• often the molecules that are buried in the center of a protein (don’t want to be exposed to water)
• no charge residues
• absence of hydrogen bonding capabilities

Question 27

Aromatic

Question 28

Phosphorylation

Answer 28

mechanism to regulate protein function