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Chem 221 - Biochemistry for Science Majors » Fall 2021 » L5 3D Structure of Proteins Part 1 of 2

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Question #1

Gobular proteins

A. are water soluble

B. have their hydrophilic side chains are on the outside, exposed to the solvent, water.

C. are roughly spherical in shape

D. have their hydrophobic amino acid side chains are in the interior of the molecule

E. All of these are correct

Question #2

The linear arrangement of amino acids in a protein is called primary structure

A. TRUE

B. FALSE

Question #3

The sequence of amino acids in a protein is listed from the C-terminus to the N-terminus.

A. TRUE

B. FALSE

Question #4

Proteins channels within membranes, have hydrophobic amino acid side chains oriented outward.

A. FALSE

B. TRUE

Question #5

Membrane proteins characteristically have a larger number of hydrophilic amino acids than cytosolic proteins.

A. TRUE

B. FALSE

Question #6

Sickle cell anemia is an important example of conservative mutation.

A. FALSE

B. TRUE

Question #7

At physiological pH, the N-terminal and C-terminal residues can form salt bridges.

A. TRUE

B. FALSE

Question #8

During the formation of the peptide bond which of the following takes place?

A. Hydrogen atom is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid

B. Hydroxyl group is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid

C. Hydroxyl group is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid

D. Hydrogen atom is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid

Question #9

Peptide bond is a _________

A. Metallic bond

B. Hydrogen bond

C. ionic bond

D. Covalent bond

Question #10

A tripeptide has _________

A. 3 amino acids and 1 peptide bond

B. 3 amino acids and 2 peptide bonds

C. 3 amino acids and 4 peptide bonds

D. 3 amino acids and 3 peptide bonds

Question #11

The peptide bond in proteins is

A. nonpolar, and fixed in a trans conformation

B. planar, and usually found in a trans configuration.

C. planar, but rotates to three preferred dihedral angles.

D. nonpolar, but rotates to three preferred dihedral angles.

E. not cleavable by hydrolysis.

Question #12

The resonance structures that can be drawn for the peptide bond indicate that the peptide bond

A. is weaker than an ordinary single bond.

B. has partial double bond character.

C. still isn't completely understood by chemists.

Question #13

How many water molecules are lost from the condensation of 100 amino acids into a polypeptide?

A. 102

B. 101

C. 99

D. 98

E. 100

Question #14

Amino acids are connected via __________ bonds, which occur between the carboxyl group of one amino acid and the amino group of another.

A. hydrogen

B. ionic

C. peptide

D. double

E. amino

Question #15

Condensation of 3 amino acids

A. releases 3 molecules of water

B. releases 2 molecules of water

C. requires 2 molecules of water

Question #16

In how many different ways can the amino acids leucine, glutamate, and glycine be arranged?

A. 5

B. 6

C. 2

D. 4

E. 3

Question #17

What accounts for peptide bond planarity within a polypeptide?

A. Partial double bond character of the peptide bond

B. The peptide bond is not planar, it can actually rotate relatively freely

C. Hydrogen bonding between amino acid side chains and water

D. The fully double bonded peptide bond

E. Electronegativity differences between nitrogen and carbon

Question #18

What does N-terminus refer to?

A. A protein chain

B. The end of a protein with a free amine group

C. The first amino acid with the abbreviation 'N' in the protein

D. The end of a protein with a free carboxylic acid group

Question #19

Which of the following statements is true about protein structure?

A. Disulfide bridges primarily maintain secondary structures, as opposed to tertiary

B. All proteins have a quaternary structure

C. pH does not change the protein conformation

D. A protein’s function depends on its spatial conformation

Question #20

The six atoms of the peptide group lie in a single plane and the configuration around the peptide bond is cis.

A. FALSE

B. TRUE

Question #21

Sickle cell anemia is an example of a genetic disease due to a problem with

A. the primary structure of the hemoglobin protein

B. the secondary structure of a protein

C. the primary structure of the myoglobin protein

D. the function of all proteins in an organism

Question #22

In the peptide Ser-Cys-Glu-Ala, the C-terminal end is ________.

A. cysteine

B. glutamic acid

C. glycine

D. alanine

Question #23

Uncharged side chains may experience ionic interactions in a protein structure.

A. FALSE

B. TRUE

Question #24

N-terminal and C-terminals may experience the formation of salt bridges

A. TRUE

B. FALSE

Question #25

In a soluble protein that resides in the cytoplasm, where is the majority of the nonpolar amino acids found in its three-dimensional structure?

A. Buried in the center of the protein

B. Localized to the C-terminus of the protein

C. On the surface of the protein

D. Randomly interspersed throughout to protein

E. Localized to the N-terminus of the protein

Question #26

The formation of a tetrapeptide.

A. Releases 4 water molecules

B. Releases 3 water molecules

C. Requires 3 water molecules

D. Requires 4 water molecules

Question #27

The ability of a particular protein to carry out its function is determined by its overall three-dimensional shape, or conformation.

A. TRUE

B. FALSE

Question #28

In the peptide Ala-Try-Gly-Phe, the N-terminal amino acid is ________.

A. glycine

B. tryptophan

C. aspartic acid

D. phenylalanine

E. alanine

Question #29

If, in a protein there is a change of an amino acid for another one, for instance a leucine is changed for lysine, the function of the protein most likely

A. will be affected

B. won't be affected

Question #30

A peptide bond is formed by hydrolysis reaction between the carboxyl group of one amino acid and the amino group of another.

A. FALSE

B. TRUE

Question #31

Where in a globular protein is the amino acid valine likely to be located?

A. The hydrophilic interior

B. The hydrophilic exterior

C. The hydrophobic exterior

D. The hydrophobic interior

Question #32

Which proteins are generally water-soluble?

A. Fibrous proteins

B. Globular proteins

C. Both globular fibrous proteins

D. Neither globular nor fibrous proteins

Question #33

To hydrolyze a pentapeptide you need

A. 4 molecules of water

B. 2 molecules of water

C. 5 molecules of water

D. 3 molecules of water

Question #34

A peptide bond is

A. an ether bond

B. a covalent bond

C. an amide bond

D. a covalent ether bond

E. a covalent amide bond

Question #35

The peptide bond of proteins resembles the bond found in

A. alkenes

B. hydrocarbons

C. alkynes

D. alkanes

Question #36

What type of interaction would occur between glutamic acid and lysine?

A. Hydrophobic

B. Ionic

C. hydrogen bonding

D. disulfide

Question #37

What type of interaction would you expect between the R groups of glutamine and serine in the quaternary structure of a protein?

A. peptide bonds

B. Hydrophobic

C. hydrogen bonding

D. Ionic

Question #38

Which of the following best describes the quaternary structure of a protein?

A. The sequence of nucleic acids

B. A polypeptide chain 3-D structure

C. How the polypeptide chains arrange in space

D. The layout of alpha-helices and beta-sheets

E. The four parts of a protein's amino acid sequence

Question #39

A protein's primary structure is determined by which of the following?

A. Alpha-helices

B. Beta-pleated sheets

C. R-group interactions

D. The hydrophobic effect

E. The linear sequence of specific amino acids

Question #40

Where, in a globular protein, is the amino acid glutamine likely to be located?

A. The hydrophobic interior

B. The hydrophobic exterior

C. The hydrophilic interior

D. The hydrophilic exterior

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