Amino Acids Quiz

Question 1

Glycine (Gly)

Answer 1

Side chain: H
Non-polar, hydrophobic, optically inactive
Only achiral amino acid

Question 2

Alanine (Ala)

Answer 2

Side chain: -CH3
Non-polar, hydrophobic
The simplest optically active AA. All other AAs build off alanine, A like the beginning of the alphabet.

Question 3

Valine (Val)

Answer 3

Side chain: -CH(CH3)2
Non-polar, hydrophobic, branched chain is a V shape

Question 4

Leucine (Leu)

Answer 4

Side chain: -CH2[CH(CH3)2]
Non-polar, hydrophobic, branched chain in shape of Y

Question 5

Isoleucine (Ile)

Answer 5

Side chain: -CH(CH3)(C2H5)
Non-polar, hydrophobic, branched chain
An isomer of leucine
One branch is longer than the other

Question 6

Proline (Pro)

Answer 6

Side chain: -CH2CH2CH2 (cyclic)
The only cyclic aliphatic
Non-polar, hydrophobic, locked geometry introduces kinks in structures

Question 7

Cysteine (Cys)

Answer 7

Side chain: -CH2-SH
Cysteine has a sulfhydryl (SH) group
Polar, forms disulfide bonds

Question 8

Methionine (Met)

Answer 8

Side chain: -(CH2)-S-(CH3)
Non-polar, hydrophobic, sulfur-containing
Start codon for protein synthesis
A methylated sulfur

Question 9

Phenylalanine (Phe)

Answer 9

Side chain: -CH2(C6H5)
Non-polar, aromatic, hydrophobic
A benzene (or phenyl) ring attached to an alanine
F letter code like its name

Question 10

Tryptophan (Trp)

Answer 10

Side chain: -indole ring
Non-polar, aromatic, hydrophobic
Largest side chain, two fused rings (double).

Question 11

Tyrosine (Tyr)

Answer 11

Side chain: -CH2(C6H4OH)
Polar, aromatic, hydrophilic
A hydroxylated (OH) phenylalanine

Question 12

Serine (Ser)

Answer 12

Side chain: -CH2OH
Polar, hydrophilic
A hydroxylated alanine

Question 13

Threonine (Thr)

Answer 13

Side chain: -CH(OH)(CH3)
Polar, hydrophilic
Three parts (HAM): hydroxyl, alanine, methyl

Question 14

Arginine (Arg)

Answer 14

Side chain: -(CH2)3-urea
Basic, hydrophilic, positively charged
Side chain has a urea (NH2-C (NH2+)(NH)) group (A pirates favorite AA, arginine).

Question 15

Lysine (Lys)

Answer 15

Side chain: -(CH2)4-NH3+
Basic, hydrophilic, positively charged

Question 16

Histidine (His)

Answer 16

Side chain: -CH2-(C3N2H4)+

Basic, hydrophilic, positively charged at low pH

Has an imidazole, an aromatic ring with two N atoms that can be protonated.

This allows His to act as a buffer that can accept or donate hydrogens when needed. Many active sites employ His to mediate reactions. His can also be used structurally in a salt bridge.

Question 17

Aspartate (Asp)

Answer 17

Side chain: -CH2COOH
Acidic, hydrophilic, negatively charged
An acidic alanine

Question 18

Glutamate (Glu)

Answer 18

Side chain: -CH2CH2COOH
Acidic, hydrophilic, negatively charged
A longer version of Aspartate

Question 19

Asparagine (Asn)

Answer 19

Side chain: -CH2CONH2
Polar, hydrophilic
Amidated Aspartate

Question 20

Glutamine (Gln)

Answer 20

Side chain: -CH2CH2CONH2
Polar, hydrophilic

Question 21

All amino acids are composed of…

Answer 21

SAAC:
Side group (R)
Amino group (-NH2)
A-carbon
Carboxyl group (-COOH)

Question 22

hydrophobic-amino acids are

Answer 22

non-polar

Question 23

aromatic amino acids

Answer 23

tryptophan
phenylalanine
tyrosine

Question 24

The neutral amino acids are

Answer 24

Qglutamine
Threonine
Serine
Ytyrosine
Nasparagine
Cysteine tyrosine

Question 25

The basic amino acids (have basic side chains )are

Answer 25

His Lies Are: basic histidine, lysine, arginine

Question 26

Proline and glycine work together to....

Answer 26

Disrupt the secondary structure of proteins Are known as a-helix breakers

Question 27

Tyrosine and tryptophan

Answer 27

Eexhibit strong UV-light absorption at 280 nm Phenylalanine absorbs at a much lower frequency Proteins and peptides that contain either Tyr or Trp can be quantified by UV-Vis spectroscopy because they absorb light in the UV light spectrum

Question 28

The acids–aspartate and glutamate–and bases—arginine, lysine and sometimes histidine

Answer 28

Form salt bridges Interactions are stronger than hydrogen bonds, but weaker than disulfide bonds Salt bridges are also found in the binding sites of proteins, often holding ligands for transport or substrates for enzymatic reactions.

Question 29

Tyr and Cys

Answer 29

Behave like alcohols, but unlike Ser and Thr, can be deprotonated easily

Question 30

PTM: Acetylation

Answer 30

Can occur on the side chain of lysine The addition of ubiquitin, a protein, is done by acetylation. Ubiquitination is important for ubiquitin-mediated protein degradation, a method for flagging proteins for recycling. Other types of acetylation are lipidations and prenylations on cysteine and N-terminal glycines.

Question 31

PTM: Phosphorylation

Answer 31

Adds a -OPO3-2 to serine, threonine, tyrosine, histidine, arginine, or lysine. This changes the electrostatics of the residue; neutral or basic AAs gain a -2 charge Cells use phosphorylation as a method of signal transduction to activate or deactivate metabolic pathways.

Question 32

PTM: Glycosylation

Answer 32

Adds a carbohydrate to an AA. Reported as Asn-X-Ser or Asn-X-Thr, where X is any residue This sequence means that glycosylation will occur at a serine or threonine that is two residues away from an asparagine

Question 33

All amino acids but ______ are chiral

Answer 33

glycine

Question 34

19/20 are L amino acids that synthesize proteins except for

Answer 34

cysteine

Question 35

The amino acid sequence of a protein is always presented in the __ to __ direction

Answer 35

N-terminus to C-terminus

Question 36

Why is arginine's side chain basic?

Answer 36

its positive charge is stabilized by resonance

Question 37

Why is histidine's side chain basic?

Answer 37

The N's have a weak affinity for an H+ and are only partly positive at neutral pH

Question 38

Acidic side chains

Answer 38

Aspartic acid Glutamic acid

Question 39

TSY in QTSYNC

Answer 39

can be phosphorylated (have -OH) group