Proteins

Question 1

Identify at least 4 different roles of proteins.

Answer 1

Catalysis, structure, transport, binding, signaling.

Question 2

What are the different groups of amino acids?

Answer 2

Non-polar, polar, non-ionizable, basic, acidic.

Question 3

Cysteine is a polar, non-ionizable amino acid. T/F

Answer 3

False. It is ionizable and uncharged.

Question 4

Leucine is a basic amino acid. T/F

Answer 4

False. Leucine is neutral.

Question 5

Phenylalanine is a non-polar amino acid. T/F

Answer 5

False. It is negative.

Question 6

Aspartate is an acidic amino acid. T/F

Answer 6

True.

Question 7

Threonine is a polar, non-ionizable amino acid. T/F

Answer 7

True.

Question 8

List at least 2 different types of post translational modification.

Answer 8

Phosphorylation, acetylation, hydroxylation, methylation.

Question 9

The amine on one amino acid can react with the carboxylate on another one.

Answer 9

True. That is how peptides form.

Question 10

One amino acid can react with another to form a peptide bond between them. T/F

Answer 10

True.

Question 11

If the two amino acids are cysteines, they can react to form a disulfide bridge. T/F

Answer 11

True.

Question 12

An amide bond can form due to the reaction of one amino acid with another. T/F

Answer 12

True.

Question 13

Rank from the smallest to the largest the following: protein, peptides, polypeptide.

Answer 13

Protein, peptide, polypeptide.

Question 14

Primary structure is held together by peptide bonds. T/F

Answer 14

True.

Question 15

Secondary structure is held together by hydrophobic interactions. T/F

Answer 15

(False?) hydrogen bonds

Question 16

Tertiary structure is held together by hydrophobic interactions. T/F

Answer 16

True. Depending on the environment.

Question 17

Quaternary structure is held together by hydrogen bonds (and other interactions). T/F

Answer 17

True. Non-covalent bonds, which are hbonds

Question 18

“Glycine-isoluecine-valine-glutamate-glutamine…” begins to spell out which part of the structure. Of the protein insulin? Its _____ structure.

Answer 18

N terminus

Question 19

What are the differences between primary structure, secondary structure, tertiary structure and quaternary structure of a protein?

Answer 19

Primary: peptide chain, peptide bonds
Secondary: Alpha helix, beta sheet, hydrogen bonds.
Tertiary: Increased folding, non-polar core. Hydrogen bonds.
Quaternary structure: Subunit complexes.

Question 20

You can’t rotate around the peptide bond, because of the double bond character. T/F

Answer 20

True

Question 21

All of the rotatable bonds in the backbone can achieve any bond angle. T/F

Answer 21

False. Rotation is limited by the peptide bond.

Question 22

The bonds before and after the alpha carbon are the rotatable bonds in a protein. T/F

Answer 22

True.

Question 23

Some of the bond angles are prohibited due to steric conflict. T/F

Answer 23

True

Question 24

What are the similarities and differences between alpha helices and beta sheets?

Answer 24

Alpha helix: non-adjacent amino acids interact with Hbon.
Beta sheet: hbond between adjacent amino acids. Antiparrallel.

Question 25

There are no regions between the secondary structures within a tertiary structure. T/F

Answer 25

False, turns and loops

Question 26

The regions between secondary structures are usually called random coil regions. T/F

Answer 26

False. Random coils pertain to primary structure.

Question 27

How many tertiary structures come together to form quaternary structure?

Answer 27

2+

Question 28

Fibrous proteins are not very abundant or important in humans. T/F

Answer 28

False. Collagen is one of the most abundant

Question 29

Protein folding is faily well understood now that crystalography is worked out.T/F

Answer 29

True

Question 30

Hydrophobic collapse is involved in some proteins but probably not the majority. T/F

Answer 30

Hydrophobic side chains will connect in a non-aqueous environment.

Question 31

The information that directs the process of the folding of a protein comes from ____.

Answer 31

DNA

Question 32

Proteins all have failry rigid structures. T/F

Answer 32

Depends on the protein.

Question 33

Proteins have greatly varying amounts of flexibility. T/F

Answer 33

True.

Question 34

Some proteins are quite rigid while others “breathe” a lot more. T/F

Answer 34

True

Question 35

A few proteins are so flexible that their entire structure can alter. T/F

Answer 35

True. Lactoferrin, glycine