Amino Acids

Question 1

Hydrophobic AA side groups

Answer 1

aliphatic: gly, ala, leu, ile, val
aromatic: phe, tyr, trp, his

Question 2

Hydrophilic AA side chains

Answer 2

polar: asn, gln
hydroxyl: ser, thr, tyr
charged: arg, lys, asp, glu, his

Question 3

Sulfur containing AA side chains

Answer 3

met and cys

Question 4

smallest AA side chain

Answer 4

gly

Question 5

imino AA side chain

Answer 5

pro

Question 6

glycine

Answer 6

gly [G]

aliphatic

https://commons.wikimedia.org/wiki/File:Glycine-2D-flat.png

Question 7

alanine

Answer 7

ala [A]

aliphatic

https://commons.wikimedia.org/wiki/File:Alanin_-_Alanine.svg

Question 8

valine

Answer 8

val [V]

aliphatic

http://www.nutriology.com/valine.html

Question 9

leucine

Answer 9

leu [L]

aliphatic

http://www.nutriology.com/leucine.html

Question 10

isoleucine

Answer 10

ile [I]

aliphatic

http://www.suggestkeyword.com/SXNvbGV1Y2luZQ/

Question 11

serine

Answer 11

ser [S]

hydroxylic

http://study.com/academy/lesson/serine-definition-structure-quiz.html

Question 12

threonine

Answer 12

thr [T]

hydroxylic

https://commons.wikimedia.org/wiki/File:Threonine_simple.png

Question 13

cysteine

Answer 13

cys [C]

hydroxylic

http://www.suggestkeyword.com/Q3lzdGVpbmU/

Question 14

methionine

Answer 14

met [M]

hydroxylic

http://www.nutriology.com/methionine.html

Question 15

tyrosine

Answer 15

tyr [Y]

aromatic and hydroxylic

https://www.healthtap.com/topics/l-tyrosine-side-effects-thyroid

Question 16

aspartic acid

Answer 16

asn [D]

acidic

http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-A/Aspartic_acid.html

Question 17

glutamic acid

Answer 17

glu [E]

acidic

http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-G/Glutamic_acid.html

Question 18

asparagine

Answer 18

asn [N]

amide

http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-A/Asparagine.html

Question 19

glutamine

Answer 19

gln [Q]

amide

http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-G/Glutamine.html

Question 20

arginine

Answer 20

arg [R]

basic

http://www.nutriology.com/arginine.html

Question 21

lysine

Answer 21

lys [K]

basic

http://www.nutriology.com/lysine.html

Question 22

histidine

Answer 22

his [H]

basic

http://glossary.periodni.com/glossary.php?en=histidine

Question 23

phenylalanine

Answer 23

phe [F]

aromatic

http://chemistry.about.com/od/imagesclipartstructures/ig/Amino-Acid-Structures/Phenylalanine.htm

Question 24

tyrosine

Answer 24

tyr [Y]

aromatic

http://resscientiae.wikia.com/wiki/File:Tyrosine.jpg

Question 25

tryptophan

Answer 25

trp [W]

aromatic

http://www.sigmaaldrich.com/catalog/product/sial/t0254

Question 26

proline

Answer 26

pro [P]

imino

https://commons.wikimedia.org/wiki/File:(S)-Proline.png

Question 27

isoelectric point

Answer 27

pH at which the compound has no net charge

pI = 1/2 (pK1 = pK2)

pK1=loss of 1st H+ (carboxy @ pK=2)
[zwitterion]=pK1-[cation]

pK2=loss of 2nd H+ (amino @ pK+10)
[anion]=pK2-[zwitterion]

Question 28

isoelectric point when there’s 2 ionizable groups

Answer 28

pI = 1/2 (sum of the pK’s on either side of the isoionic species)

if aa is acidic: pI = 1/2 (sum of 2 acid pK’s)
if aa is basic: pI = 1/2 (sum of 2 basic pK’s)

Question 29

Amino Acid configurations

Answer 29

all aa, except gly, are chiral

all aa in human physiological proteins are in L configuration (rotate light to the left)
bacteria can have D configuration-useful in medication

Question 30

peptide bonds

Answer 30

how two aa join at the amino end of one to the carboxyl end of the other

dehydration rxn

bond has no charge

http://www.mun.ca/biology/scarr/iGen3_06-03.html

bond between H3N-C and between C-COO- is 120 degrees

Question 31

Amino Acid Structure

Answer 31

+H3N-CHR-COO-

zwitterion-both positive and negative

overall neutral at physiological pH

amphoteric-both an acid and a base

amino pKa=10
carboxyl pKa=2