Protien Structure And Function

Question 1

What is the positively charged region of an amino acid?

Answer 1

Amino group, NH3+

Question 2

What is the negatively charged part of an amino acid?

Answer 2

Carboxyl group, COO-

Question 3

At physiological pH, amino acids are _____. The carboxylic acid ionizes above pH 2. The amino group ionizes below pH9.

Answer 3

Zwitterions

Question 4

The ____ is the pH at which half the functional groups (R groups) are protonated and half are un-protonated

Answer 4

pK

Question 5

When the pH = pK, a _____ region is formed.

Answer 5

Buffering region

Question 6

The _____ ____ is the pH at which the molecule has a neutral charge.

Answer 6

Isoelectric point (pI)

Question 7

Some amino acids have side chains with dissociable protons, the pK of their R groups are near physiological pH. These amino acids often participate in _____.

Answer 7

Catalysis

Question 8

When and amine group of one amino acid bonds with the carboxylic acid of another amino acid, a ____ _____ is formed. This is a _____ reaction.

Answer 8

Peptide bond
Dehydration

Question 9

What type of bond is shown in the picture

Answer 9

Peptide bond

Question 10

The 6 Aliphatic (nonpolar) amino acids are _________.

Answer 10

Glycine, alanine, proline, valine, leucine, and isoleucine

Question 11

The 3 aromatic amino acids are ______.

Answer 11

Phenylalanine, tyrosine, and tryptophan

Question 12

The 4 polar, uncharged amino acids include:

Answer 12

Asparagine, glutamine, serine, and threonine

Question 13

Polar amino acids are often found on the _____ of proteins. They all have _____ hydropathy indices.

Answer 13

Surface
Negative

Question 14

The 2 sulfur containing amino acids are:

Answer 14

Methionine, cysteine

Question 15

The 5 charged amino acids are _______ . They have a charge at near physiological pH and promote protein folding.

Answer 15

Aspartate, glutamate (negative)
Arginine, lysine, histidine (positive)

Question 16

_____ structure refers to the linear sequence of amino acids that make up a protein.

Answer 16

Primary

Question 17

In proteins amino acids are _____ attached to one another through peptide bonds.

Answer 17

Covalently

Question 18

The alpha helix is a common ____ structure.

Answer 18

Secondary

Question 19

Beta sheets are a type of ____ structure.

Answer 19

Secondary

Question 20

The ____ ____ is a tertiary structure domain that forms a valley that binds and hydrolyzes ATP

Answer 20

Actin cleft

Question 21

Amino acids in the interior are hydrophobic such as ____, _____ , ____. Amino acids at the surface are polar such as ____, ____ , ____.

Answer 21

Isoleucine, valine, phenylalanine
Serine, threonine, and tyrosine

Question 22

One or more addition of ______ protects amino acids from degradation. This is common on extra cellular domains of trans membrane proteins.

Answer 22

Carbohydrates (sugars)

Question 23

The covalent attachment of _____ to amino acids helps to anchor them to membranes

Answer 23

Lipids

Question 24

Serine, threonine, and tyrosine side chains can be _______. Enzymes called _____ hydrolyze ATP and transfer a phosphate to the hydroxyl group of the amino acid.

Answer 24

Phosphorylated
Kinases

Question 25

Cysteine can form a covalent ______ bond that maintains the folded shape. This is a type of ____ modification.

Answer 25

Disulfide Post-translational

Question 26

The interactive surfaces of proteins often have _____ amino acids in the quaternary structure

Answer 26

Hydrophobic 

Question 27

Transient changes in quaternary structure of the ____ ____ _____ mediates, beta adrenergic receptor signaling.

Answer 27

G Protein complex

Question 28

Which of the amino acids below would most likely be located at the solvent exposed surface of an enzyme? Isoleucine, threonine, valine, phenylalanine or alanine

Answer 28

Threonine

Question 29

At physiological pH what is glycine’s net charge?

Answer 29

Zero

Question 30

The pH at which 50% of molecules with an ionizable group are protonated and 50% are on protonated is the:

Answer 30

pKa

Question 31

Which of the amino acids below form covalent bonds through their side chains that stabilize proteins folded structures? Histidine, glutamine, glutamate, tyrosine, or cysteine?

Answer 31

Cysteine

Question 32

In and amphipathic, alpha helix, which amino acids side chain would project out towards a nonpolar solvent, such as a lipid membrane? Glutamate, arginine, proline, isoleucine, or serine?

Answer 32

Isoleucine

Question 33

In a amphipathic alpha helix, which amino acid side chains would project out towards a polar solvent? Valine, proline isoleucine, methionine, or serine

Answer 33

Serine

Question 34

Which of the amino acids can be modified by phosphorylation after a protein is translated?

Answer 34

Serine, tyrosine, and threonine

Question 35

Which post translational modification is most likely to anchor a protein in a membrane?

Answer 35

Palmitoylation of a cysteine

Question 36

Which of the phrases below best describes the quaternary structure of adult hemoglobin?

Answer 36

Heterotetramer