Chapter 1 concepts

Question 1

how many standard amino acids are there?

Answer 1

20

Question 2

what is the pKa for all alpha carboxilic amino acids?

Answer 2

2.1

Question 3

what is the pKa for all the alpha amino groups?

Answer 3

9.5

Question 4

how do you find all amino acids at physiological pH of 7.4?

Answer 4

they are all ionized (NH3; amino group has a positive charge, COO; carboxyl group has a negative charge)

Question 5

what amino acid contains a secondary amino group?

Answer 5

proline

Question 6

how do you find all alpha carboxyl’s at low pH?

Answer 6

protonated (from COO- to COOH)

Question 7

what is the isoelectric point?

Answer 7

pH at which an amino and carboxyl group are ionized.

the charges of the amino acid combined make the amino acid neutral

Question 8

If the amino acids placed in a solution and polarized light is made to pass through the solution, all amino acids will rotate towards what side?

Answer 8

left

Question 9

What is the simplest amino acid?

Answer 9

glycine

Question 10

where can glycine be found?

Answer 10

bends and turns

Question 11

what are the branched amino acid?

Answer 11

valine, isoleucine, leucine

Question 12

what are the sulfur containing amino acids?

Answer 12

cysteine, methionine

Question 13

what sulfur containing amino acid has its sulfur free to make bonds?

Answer 13

cysteine

Question 14

what amino acids is formed by joining of two sulfurs of cysteine?

Answer 14

cystine

Question 15

what happens with proline’s amino group?

Answer 15

it is not really free since is helps with its ring formation

Question 16

What is special about proline?

Answer 16

it is a helix breaker, it changes the alpha helix to other shape.

Question 17

what are the aromatic amino acids?

Answer 17

phenylalanine, tyrosine, tryptophan

Question 18

what are the basic amino acids?

Answer 18

arginine and lysine due to additional NH2 group

Question 19

what is so special about histidine?

Answer 19

it can accept or donate protons so its a good buffer

Question 20

What are the acidic amino acids?

Answer 20

aspartic acid and glutamic acid due to extra COOH group

Question 21

What are the neutral amino acids?

Answer 21

aparagine and glutamine

Question 22

What are the hydroxyl containing amino acids?

Answer 22

serine, threonine, tyrosine

Question 23

what are hydroxyl in amino acids are the site of?

Answer 23

site for post-translational modification like phosphorylation or glycosylation

Question 24

What does it mean the more positive the hydropathic index is?

Answer 24

the more hydrophobic the side chain of the amino acid will be.

Question 25

What are the nonpolar amino acids?

Answer 25

glycine, alanine, branched amino acids, proline

Question 26

where do you find nonpolar amino acids?

Answer 26

in the hydrophobic core of a protein molecule or in the transmembrane portion.

Question 27

What aromatic amino acid is nonpolar?

Answer 27

phenylalanine

Question 28

is tyrosine polar or non polar?

Answer 28

it is polar due to its OH

Question 29

is tryptophan polar or nonpolar?

Answer 29

it is polar

Question 30

what amino acids are polar uncharged?

Answer 30

amino acids that have amide or hydroxyl groups; asparagine, glutamine, serine, threonine, cysteine

Question 31

in proteins where do you find polar uncharged amino acids?

Answer 31

in the surface