Biochemistry

Front 1

Name of the covalent bonds that link amino acids to each other

Back 1

Peptide bonds

Front 2

How many amino acids are used in synthesizing proteins?

Back 2

There are 20 amino acids

Front 3

Proteins are __________ of amino acids

Back 3

heteropolymers

Front 4

Name the common structural features of an amino acid

Back 4

amino group, side chain (R), carboxyl group, hydrogen

Front 5

Which structural feature influences the way amino acids behave?

Back 5

R groups, since they vary in structure, size and charge

Front 6

What is the predominant form of the amino acid at physiological pH?

Back 6

Both the carboxylic acid and amino group are ionized

Front 7

Using organic nomenclature, which carbon is labeled as 1?

Back 7

C terminus carboxyl group carbon is 1, then assign ascending numbers to carbons down the R group

Front 8

How does biochemical designation label amino acids?

Back 8

start from alpha carbon and assign greek letters to carbons down the R group

Front 9

Through what process is a peptide bond formed?

Back 9

Condensation, H20 is lost

Front 10

How are α-amino acids chiral?

Back 10

α-amino acids are chiral because the α-carbon has always four different substituents and is tetrahedral

Front 11

α-carbon is the ________ center

Back 11

chiral

Front 12

How many possible stereoisomers can amino acids have? Describe them.

Back 12

Amino acids can have 2 possible stereoisomers that are non-superimposable, mirror images of each other (aka enantiomers)

Front 13

The amino acids enantiomers are labeled....

Back 13

D or L

Front 14

In proteins, what is the form of the amino acid enantiomer?

Back 14

L is the form of amino acids used and incorporated into proteins

Front 15

Why is it necessary to have all of the subunits be of the sam L stereoisomer?

Back 15

In order to build a stable, repeating, structure that is a polypeptide chain

Front 16

How do cells specifically synthesize L isomers of amino acids?

Back 16

The active sites of aa synthesis enzymes are asymmetric, causing the reactions they catalyze to be stereospecific

Front 17

Where have D amino acid residues been found?

Back 17

Only in a few proteins, generally very small peptides

Front 18

Why do stereoisomers have different effects in humans?

Back 18

They are perceived by different receptors

Front 19

Name the five general groups that common amino acids can be placed in?

Back 19

(1) Nonpolar, aliphatic
(2) Aromatic
(3) Polar, uncharged
(4) Positively charged
(5) Negatively charged

Front 20

What is the categorization/classification of amino acids based on?

Back 20

Based on R groups polarity (tendency to interact with water) at biological pH (near pH 7)

Front 21

Name the amino acids that are classified as nonpolar, aliphatic (There are 7 total)

Back 21

Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, Methionine

Front 22

What distinguishes the amino acid side chains (R groups) in the nonpolar, aliphatic classification?

Back 22

AA side chains are nonpolar and hydrophobic. Composed of simple carbon chains. Make mostly hydrophobic contacts

Front 23

Name the 4 amino acids whose side chains tend to cluster by means of hydrophobic interactions?

Back 23

Alanine (Ala), Valine (Val), Leucine (Leu), Isoleucine (Ile)

Front 24

Name the amino acid that is one of two sulfer containing aa's that has a nonpolar thioester group

Back 24

Methionine (Met)

Front 25

Name the amino acid that has a side chain with a distinctive cyclic structure

Back 25

Proline (Pro)

Front 26

Name the amino acids classified as aromatic (There are 3 total)

Back 26

Phenylalanine, Tyrosine, Tryptophan

Front 27

What distinguishes the aa side chains (R groups) classified as aromatic?

Back 27

Contain aromatic rings as side chains and generally are generally hydrophobic (nonpolar)

Front 28

Which amino acid R group (that is aromatic) can form H bonds-polar?

Back 28

Tyrosine

Front 29

Name the amino acids classified as polar, uncharged (There are 5 total)

Back 29

Serine, Threonine, Cysteine, Asparagine, Glutamine

Front 30

What distinguishes the aa side chains that are classified as polar, uncharged?

Back 30

They are hydrophilic (more soluble in water) and can form hydrogen bonds with water

Front 31

Which aa in the polar, uncharged group can form disulfide bonds?

Back 31

Cysteine (Cys)

Front 32

Disulfide bonds are important in
___________

Back 32

antibodies

Front 33

Reversible formation of a disulfide bond occurs by _______

Back 33

oxidation of two molecules of Cys

Front 34

Disulfide-linked residues are strongly __________

Back 34

hydrophobic

Front 35

Name the amino acids that are classified as positively charged (there are 3 total)

Back 35

Lysine, Arginine, Histidine