Chapter 14:

Question 1

Amino acid sequence helps determine _________ which determines its ______

Answer 1

3-D conformation of a protein
Properties

Question 2

True of False: Mutation changes amino acid sequence that can affect the fucntion of a protein

Answer 2

true

Question 3

Amino acids are linked by ______ to form _______

Answer 3

peptide bonds (amide bonds) which are covalent
Polypeptide chains

Question 4

The amino acids in a polypeptide are linked by amide bonds formed between
the _____ group of one amino acid and the _____ group of the next

Answer 4

carboyxl
amino

Question 5

The linking of two amino acids is accompanied by

Answer 5

the loss of a molecule of water

Question 6

What is taken at the beginning of the polypeptide chain?

Answer 6

Amino terminal end

Question 7

What is taken at the end of the polypeptide chain?

Answer 7

Carboxyl terminal end

Question 8

Polypeptide chain costs of:

Answer 8

a repeating part called main chain/ backbone
a variable part consisting of distinctive amino acid side chains

Question 9

C=0 is important for the polypeptide chain since it is a

Answer 9

good hydrogen bond acceptor

Question 10

N-H is important for the polypeptide chain since it is a

Answer 10

good hydrogen bond donor (except proline)

Question 11

In some proteins, the polypeptide chain can be cross linked by

Answer 11

disulfide bonds (covalent bond)

Question 12

Disulfie bonds form by

Answer 12

the oxidation of two cystenines (S-S

Question 13

Peptide bond of polypeptide chain characteristics:

Answer 13

planar (6 atoms lie in a plane)
partial double bond character because of resonance –> no rotation of the bond
uncharged

Question 14

Many peptide bonds are in ___ configuration and why?

Answer 14

trans configration
minimize steric clashes between neighboring R groups

Question 15

The freedom of rotation about two bonds of each amino acid allows

Answer 15

proteins to fold in many different ways

Question 16

Primary structure of amino acids

Answer 16

Linear sequence of amino acids connected by peptide bonds
Gives identity and characteristics to a protein

Question 17

Secondary structure of amino acids

Answer 17

three dimensional structure formed by hydrogen bonds between peptide NH and CO groups of amino acids
local interactions between one part of polypeptide backbone and another affect protein structure
Ex. alpha helix, beta sheets, turns

Question 18

Alpha Helix

Answer 18

Secondary structure
Tighly coiled rodlike structure with R groups pointing out
C=O of each peptide bond is hydrogen bonded to the N-H of the fourth amino
acid away

Question 19

Several factors that can disrupt alpha helix

Answer 19

1. proline
2. strong electrostatic repulsion
3. steric crowding
4. serine, aspartate, and asparagine, compete for hydrogen bonds

Question 20

Beta sheet

Answer 20

Secondary structure
Formed by adjacent beta strands which are fully extended
R groups alternate above and below the plane
Linked by H bonds
May be parallel, antiparallel, or mixed

Question 21

Supersecondary Structure (motifs)

Answer 21

repeating and combination of secondary structure

Question 22

Alpha helix and Beta pleated Sheet Differences

Answer 22

1. H bonds in alpha helix are formed between peptide groups of same chain while in beta sheet formed between different chains
2. Alpha helix not fully extended and beta sheet is fully extended

Question 23

What two amino acids are found in reverse turns?

Answer 23

Proline (cyclic structure) and Glycine (flexibility)

Question 23

Alpha helix and Beta pleated Sheet Similarities

Answer 23

Both regular repeating structure
Stabilized by H bonds

Question 24

Turns/ Loops

Answer 24

secondary structure
On surface of proteins which help with interactions between other proteins and environment

Question 25

Reverse turns

Answer 25

Parts where polypeptide chain fold back on itself for protein to fold
Give rise to tertiary structure

Question 26

Fibrous proteins

Answer 26

Structural role
Secondary structure
Ex. Keratin and collagen

Question 27

Globular Proteins

Answer 27

Secondary structure and folded into tertiary structure
Ex. myoglobin and hemoglobin

Question 28

In fibrous protein of collagen, ___ appears at every third residue

Answer 28

glycine

Question 29

What is essential for stabilizing collagen ?

Answer 29

Hyp: Hydroxyproline

Question 30

Hydroxyproline

Answer 30

requires vitamin C for its synthesis
Holds collagen helix together

Question 31

Scurvey

Answer 31

disease resulting from a defiency of vitamin are result of fragile collagen

Question 32

protein folding is driven by

Answer 32

hydrophobic effect: strong tendency of hydrophobic residues to avoid contact with water

Question 33

Tertiary structure

Answer 33

3-D arrangmeent of all atoms in a protein (single polypeptide chain)
Ex. Myoglobin

Question 34

Quartenary structure

Answer 34

Arrangement of subunits with respect o one another and is more than one polypepitde chain
Ex. Hemoglobin

Question 35

Forces stabilizing primary structure

Answer 35

peptide bonds

Question 36

Forces stabilizing secondary structure

Answer 36

Hydrogen bonds between NH and CO groups of amino acids

Question 37

Forces stabilizing tertiary structure

Answer 37

interactions between R groups (hydrogen, hydrophobic, disulfide, ionic, electrostatic, van der waals)

Question 38

Forces stabilizing quatenary structure?

Answer 38

Noncovalent forces between subunits

Question 39

Denaturation

Answer 39

Loses 3D structure (2, 3, 4) caused by breaking of noncovalent interactions to result in loss of protein function

Question 40

Folded refers to

Answer 40

more organized, reduced entropy

Question 41

Causes of denaturation

Answer 41

1. heat
2. pH changes
3. detergent
4. urea and guanidine hydrochloride
   beta mercaptoethanol

Question 42

What are two forces that overcome entropy decrease and drive protein folding process forward?

Answer 42

1. Decrease in energy, negative change in entropy
2. hydrophobic effect