Buffers and peptides

Question 1

in pure water, [h3o+]=[oh-]=

Answer 1

1 times 10^-7

Question 2

kw=[h+][OH-]=

Answer 2

10^-14 M

Question 3

an increase in [H+] is always

Answer 3

accompanied by a decrease in [OH-]

Question 4

lower pka means that group favors

Answer 4

deprotonation at physiological pH

Question 5

hh equation

Answer 5

pH=pKa+log[A-]/[HA]

Question 6

buffering capacity is the greatest at the _____ and most effective within

Answer 6

pKa, within +/- 1 pH units

Question 7

changing the pH by 1 unit changes the ration of acid to conjugate base by a factor of _____

Answer 7

10

Question 8

most common amino acids are r or s

Answer 8

s (except for cysteine)

Question 9

isobaric isomers

Answer 9

leucine and isoleucone

Question 10

b-branched

Answer 10

valine and isoleucine

Question 11

pKr of tyrosine

Answer 11

10

Question 12

nonpolar/hydrophobic

Answer 12

alanine, valine, leucine, isoleucine, methionine, proline, phe

Question 13

arginine group

Answer 13

guanidinium

Question 14

histidine has a ____ ring

Answer 14

imidazole

Question 15

pka =
in terms of ka

Answer 15

-log10ka

Question 16

lower pka means what at physiological ph

Answer 16

deprotonation

Question 17

does a- always have negative charge

Answer 17

no

Question 18

if pH=pKa what does that mean for wa and wb

Answer 18

[a-]=[ha]

Question 19

what happens when ph=pka for sa or sb

Answer 19

a strong acid or strong base completely dissociates and neutralizes a wa or cb

Question 20

smallest of the nonpolar side chains

Answer 20

alanine

Question 21

methionine

Answer 21

nonpolar despite sulfar, long and flexible

Question 22

pkr of tyrosine

Answer 22

10

Question 23

aromatic amino acids absorb UV wavelengths why

Answer 23

conjugated pi systems give e= tranistions of the right energies

Question 24

tryp is also _____ at 300-350 nm

Answer 24

fluorescent

Question 25

___ and ____ hydroxyl groups give h bonding potential

Answer 25

serine and threonine

Question 26

cysteine

Answer 26

can form weak h bonds, and good nucleophile

Question 27

cysteine pkr

Answer 27

8

Question 28

aspartate pkr

Answer 28

3.5

Question 29

glutamate pkr

Answer 29

4

Question 30

lysine pkr

Answer 30

10.5

Question 31

arginine pkr

Answer 31

12.5

Question 32

histidine pkr

Answer 32

6

Question 33

which has indole ring

Answer 33

tryptophan

Question 34

guanidium ring

Answer 34

arginine

Question 35

imidazole ring

Answer 35

histidine

Question 36

fluorescent at 300 nm

Answer 36

tryptophan

Question 37

side chain amide groups provide even more h bonding potential

Answer 37

asparagine and glutamine