Question 1

What name is given to the process seen in this animation?To view the animation, click here. Then click on the image to start the animation.

Accepted Answer

dehydration synthesis The linking of the monomers involves the removal of water

Question 2

Which of the following parts of an amino acid vary among different amino acids?

Accepted Answer

the side chain, or R group While all amino acids contain an amino group, a carboxyl group and a hydrogen bound to the central carbon, the R groups vary among the 20 different amino acids.

Question 3

Which class(es) of amino acids possess side chains that would be unable to form hydrogen bonds with water?

Accepted Answer

amino acids with nonpolar side chains Nonpolar side chains are hydrophobic.

Question 4

Each of the figures above represents a peptide with three amino acids linked together (a tripeptide). In which figure are the N-terminus, C-terminus, Amino Group, and Carboxyl Group correctly labeled?

Accepted Answer

A. This figure correctly identifies the components of a peptide (or polypeptide) chain

Question 5

what type of bond joins the monomers in a protein's primary structure?

Accepted Answer

peptide

Question 6

Proteins are polymers of _____.

Accepted Answer

b) amino acids

Question 7

Which of these illustrates the secondary structure of a protein?

Accepted Answer

Alpha helices and beta pleated sheets are characteristic of a protein's secondary structure.

Question 8

The secondary structure of a protein results from _____.

Accepted Answer

HYDROGEN BONDS-Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges.

Question 9

Tertiary structure is NOT directly dependent on _____.

Accepted Answer

peptide bonds Peptide bonds link together the amino acids of a protein's primary structure.

Question 10

______ structure is achieved when a protein folds into a compact, three dimensional shape stabilized by interactions between side-chain R groups of amino acids

Accepted Answer

tertiary

Question 11

tructure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain

Accepted Answer

secondary

Question 12

___ structure is the sequence of amino acids in a protein

Accepted Answer

primary

Question 13

___ structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex

Accepted Answer

quaternary

Question 14

Sort the images according to the level of structure in the proteins shown.Sort the items into the appropriate bin.

Accepted Answer

The tertiary and quaternary structures of proteins&mdash;how they fold into their overall three-dimensional shapes, and how different protein subunits come together to interact&mdash;both ultimately depend on the primary structure, the sequence of amino acids in the proteins. A different sequence of amino acids will lead to different secondary structures and a different shape of the overall protein.

Question 15

How many different primary sequences can be generated by randomly assembling amino acids into peptides that are five residues long?

Accepted Answer

20^5=3,200,000 Correct. Given 20 major amino acids, there are 20 possibilities at each position resulting in 20&times;20&times;20&times;20&times;20=205 different primary sequences.

Question 16

A major limitation of the ribbon model of a protein is:

Accepted Answer

-it gives a false sense of open space in the protein  Only the space filling model gives a true sense of how tightly packed the space inside the folded protein really is.

Question 17

In Figure 3.2, green R-groups are nonpolar and pink R-groups are polar. Which statement best explains this difference in terms of the relative electronegativities of C, H, O, and N?

Accepted Answer

Green R-groups contain primarily C and H, which have approximately equal electronegativities and lack O; most pink R-groups contain a highly electronegative O atom. Correct. In addition, Met and Cys (nonpolar) contain only C, H, and S. In Met, S is bonded to C, which has an approximately equivalent electronegativity. In Cys, S is bonded to C and to H, which has an approximately equivalent electronegativity.

Question 18

Which of the following is true of protein folding?

Accepted Answer

Some proteins can fold spontaneously. Correct. This was shown in experiments with ribonuclease by Anfinsen in the 1950's.

Question 19

Where is the information that directs different polypeptides to fold into different shapes?

Accepted Answer

in the primary structure

Question 20

What is an active site?

Accepted Answer

the position in an enzyme where substrates bind

Question 21

Why are proteins not considered to be a good candidate for the first living molecule?

Accepted Answer

The cannot serve as a template for replication

Question 22

Which of the following types of amino acids would you predict to be present in the DNA binding sites of these proteins?

Accepted Answer

basic amino acids

Question 23

In a polypeptide, what bonds are responsible for the primary structure?

Accepted Answer

peptide bonds

Question 24

What features of protein folding and function are revealed by calmodulin and prions

Accepted Answer

More than one shape is possible for a protein and different shapes function differently or not at all.

Question 25

Nonpolar amino acid residues are typically found in the interior of globular proteins like trypsin. Which chemical force is most directly responsible?

Accepted Answer

hydrophobic interactions

Question 26

Proteins are polymers of

Accepted Answer

amino acids

CHAPTER 3 PROTEINS

Unlock all answers in this set

Haven't found what you need?