Amino Acids

Question 1

are the most abundant and functionally diverse molecules in living systems

Answer 1

Proteins

Question 2

What proteins permit muscle movement?

Answer 2

contractile proteins

Question 3

Proteins that direct and regulate metabolism in the body

Answer 3

enzymes and polypeptide hormones

Question 4

forms a framework for the deposition of calcium phosphate crystals, acting like the steel cables in reinforced concrete

Answer 4

protein collagen

Question 5

In the bloodstream, proteins, such as _________ and _________ shuttle molecules essential to life,

Answer 5

hemoglobin and plasma albumin

Question 6

fight infectious bacteria and viruses

Answer 6

immunoglobulins

Question 7

Parts of amino acid

Answer 7

carboxyl group, primary amino group, primary carbon, side chain

Question 8

Explain what happens to amino acids at physiologic pH (7.4)

Answer 8

the carboxyl group is dissociated, forming the negatively charged carboxylate ion (–COO–) and the amino group is protonated (–NH3+).

Question 9

In proteins, almost all of these carboxyl and amino groups are combined through

Answer 9

peptide linkage

Question 10

Explain what trait of proteins are due to them having only peptide bonds?

Answer 10

In general, they are not available for chemical reaction except for hydrogen bond formation

Question 11

We classify amino acids by their?

Answer 11

Side chain

Question 12

Explain the properties of a nonpolar side chains

Answer 12

does not gain or lose protons or participate in hydrogen or ionic bonds thought of as “oily” or lipid-like, a property that promotes hydrophobic inter-actions

Question 13

What happens to nonpolar amino acids in aqueous solutions?

Answer 13

the side chains of the nonpolar amino acids tend to cluster together in the interior of the protein

Question 14

When are nonpolar R groups found at the surface of the protein?

Answer 14

When they are located in a hydrophobic environment such ass a membrane (lipid environments)

Question 15

Sickle cell anemia is caused by which amino acid replacement?

Answer 15

polar glutamate with nonpolar valine at the sixth position in the β subunit of hemoglobin

Question 16

which amino acid has rigid 5 membered ring structure since the R group is also connected to the amino group

Answer 16

Proline

Question 17

Proline is frequently reffered to as an?

Answer 17

“imino acid”

Question 18

The unique geometry of proline contributes to what aspects in the body

Answer 18

the formation of the fibrous structure of collagen and often interrupts the α-helices found in globular proteins

Question 19

These amino acids have zero net charge at physiologic pH,

Answer 19

Amino acids with uncharged polar side chains

Question 20

Amino acids with uncharged polar side chains that can lose a proton at an alkaline pH

Answer 20

cysteine and tyrosine

Question 21

Amino acids with uncharged polar side chains that contain a polar hydroxyl group that can participate in hydrogen bond formation

Answer 21

Serine, threonine, and tyrosine

Question 22

The side chain of these amino acids with uncharged polar side chains each contain a carbonyl group and an amide group, both of which can also participate in hydrogen bonds.

Answer 22

asparagine and glutamine

Question 23

The side chain of cysteine contains

Answer 23

sulfhydryl (thiol) group (–SH)

Question 24

Explain disulfide bonds

Answer 24

The side chain of cysteine contains a sulfhydryl (thiol) group (–SH), which is an important component of the active site of many enzymes. In proteins, the –SH groups of two cysteines can be oxidized to form a covalent crosslink called a disulfide bond (–S–S–). Two disulfide-linked cysteines are referred to as “cystine.”

Question 25

The polar hydroxyl group of ______,________, and _____ can serve as a site of attachment for structures such as a ____________

Answer 25

serine; threonine; and, rarely, tyrosine phosphate group.

Question 26

They can serve as a site of attachment for oligosaccharide chains in glycoproteins

Answer 26

the amide group of asparagine, as well as the hydroxyl group of serine or threonine

Question 27

The amino acids ______ and ______ are proton donors. At physiologic pH, the side chains of these amino acids are fully ionized, containing a negatively charged carboxylate group (–COO–).

Answer 27

aspartic glutamic acid

Question 28

Amino acids that are negatively charged at physiologic pH

Answer 28

Amino acids with acidic side chain

Question 29

The side chains of these amino acids accept protons

Answer 29

basic amino acids

Question 30

At physiologic pH, the R groups of _______ and ______ are fully ionized and positively charged.

Answer 30

lysine and arginine

Question 31

Basic amino acid that is weakly basic, and the free amino acid is largely uncharged at physiologic pH.

Answer 31

Histidine

Question 32

This is an important property of histidine that contributes to the buffering role it plays in the functioning of proteins such as hemoglobin

Answer 32

when histidine is incorporated into a protein, its R group can be either positively charged (protonated) or neutral, depending on the ionic environment provided by the protein. Histidine is the only amino acid with a side chain that can ionize within the physiologic pH range.

Question 33

explain amino acid naming rule | Unique first letter:

Answer 33

If only one amino acid begins with a given letter, then that letter is used as its symbol. For example, V = valine.

Question 34

explain amino acid naming rule | Most commonly occurring amino acids have priority

Answer 34

If more than one amino acid begins with a particular letter, the most common of these amino acids receives this letter as its symbol. For example, glycine is more common than glutamate, so G = glycine.

Question 35

explain amino acid naming rule | Similar sounding names

Answer 35

Some one-letter symbols sound like the amino acid they represent. For example, F = phenylalanine, or W = tryptophan (“twyptophan” as Elmer Fudd would say).

Question 36

explain amino acid rule | Letter close to initial letter

Answer 36

For the remaining amino acids, a one-letter symbol is assigned that is as close in the alphabet as possible to the initial letter of the amino acid, for example, K = lysine. Furthermore, B is assigned to Asx, signifying either aspartic acid or asparagine, Z is assigned to Glx, signifying either glutamic acid or glutamine, and X is assigned to an unidentified amino acid.

Question 37

What are the four rules regarding naming common amino acids

Answer 37

Unique first letter Most commonly occurring amino acids have priority Similar sounding names Letter close to initial letter

Question 38

The α-carbon of an amino acid is attached to four different chemical groups (asymmetric) and is, therefore, a?

Answer 38

chiral or optically active carbon atom

Question 39

An example of an amino acid that is not a chiral or optically active carbon atom

Answer 39

glycine

Question 40

Amino acids that are not optically active or chiral

Answer 40

Stereoisomers, optical isomers, or enantiomers

Question 41

What sturctural configuration can you spot amino acids in proteins?

Answer 41

L-configuration

Question 42

D-configuration amino acids can be found where?

Answer 42

some antibiotics and bacterial cell walls

Question 43

Amino acids in aqueous solution contain?

Answer 43

weakly acidic α-carboxyl groups and weakly basic α-amino groups and ionizable group in its side chain

Question 44

both free amino acids and some amino acids combined in peptide linkages can act as ________ due to them containing a weak acid and base.

Answer 44

buffers