Amino Acids

Question 1

What AAs are non-polar and non-aromatic?

Answer 1

Leucine, Isoleucine, Methionine, Proline, Valine, Alanine, Glycine (7)

Question 2

What are the negatively charged AAs?

Answer 2

Glutamic Acid and Aspartic Acid

Question 3

What are the positively charged AAs?

Answer 3

Histidine, Lysine, Arginine

Question 4

What AAs are nonpolar, aromatics?

Answer 4

Tryptophan, Tyrosine, Phenylalanine

Question 5

Why are some AAs considered essential?

Answer 5

Because the human body cannot produce them, they must be obtained via diet

Question 6

What is the fundamental structure of AAs?

Answer 6

Central alpha carbon - glue which hold amino acid together, which is bonded to four groups:

• An amino group
• A carboxyl group
• A hydrogen atom
• A unique side chain

Question 7

What is an R group?

Answer 7

The varying side chain of an amino aced, that give each one its unique properties - size, polarity, charge and how it interacts with other parts of the body

Question 8

What is the n-terminus?

Answer 8

The amino group which is usually a base and pronated in the environment of the cell - giving it a positive charge

Question 9

What is the c-terminus?

Answer 9

Usually a carboxyl group - and acid which is typically depronated in the aqueous environment of the cell, giving it a negative charge

Question 10

What is a zwiitterion?

Answer 10

Because the uncharged amino acids have a plus one and minus one charge under physiological conditions
Ions cancel out producing a net neutral charge

Question 11

Explain the concept of “like attracts like”

Answer 11

Hydrophobic and hydrophilic interactions

Question 12

What are the 5 classifications of AAs?

Answer 12

Non-polar allopathic
Non-polar aromatic
Polar uncharged
Polar basic
Polar acidic

Question 13

What are non-polar alipathic AAs?

Answer 13

R-groups contain non-aromatic hydrocarbon chains

Question 14

What are non-polar aromatic AAs?

Answer 14

R-groups contain aromatic rings (except for histidine which has an aromatic ring but is basic AA)

Question 15

What are polar AAs?

Answer 15

Can be either charged or uncharged, as the opposite to non-polar AAs, the polar side groups are very hydrophilic and want to maximize their interactions with other polar molecules such as water, contain atoms capable of hydrogen bonding, typically make up the outside of proteins, also have a negative or positive charge

Question 16

What is an acidic AA?

Answer 16

Aspartic and glutamic acid

Have a negative charge (aside from one at C terminus) at physiological pH

Question 17

What is a basic AA?

Answer 17

Lysine and arginine

Have an additional positive charge (aside from one at N terminus) at physiological pH

Question 18

What are the special properties of glycine and proline?

Answer 18

When added into a protein, they will destabilize/break down local alpha helical secondarystructure

Question 19

What are the special properties of serine, threonine and tyrosine?

Answer 19

Side groups are most often targets of phosphorylation - addition of negatively charged phosphate to a molecule changing the structure and function
Each one has a hydroxyl functional group

Question 20

What are the special properties of aspartic and glutamic acid?

Answer 20

Can mimic a permanently phosphorylated functional group
When substituted for serine, threonine or tyrosine - able to mimic presence of phosphate group
Phosphomimetic effect

Question 21

What are the special properties of cysteine?

Answer 21

Able to produce covalent disulfide bonds with other cysteine residues, holding together the subunits of a polypeptide

Question 22

What are the special properties of basic and acidic residues?

Answer 22

Can interact to form salt bridges due to their attractive positive and negative charges - they play aw important role in stabilizing proteins

Question 23

What are the two primary methods for synthesizing AAs in the lab?

Answer 23

Strecker synthesis

Gabriel synthesis