Chapter 7: Protein Function: Myoglobin and Hemoglobin, Muscle Contraction, and Antibodies

Question 1

exhibits a hyperbolic O2-binding curve.

Answer 1

Myoglobin

Question 2

can adopt the deoxy (T) or oxy (R) conformation

Answer 2

Hemoglobin

Question 3

triggers conformational changes in hemoglobin

Answer 3

oxygen binding

Question 4

why does oxygen binding trigger conformational changes in hemoglobin

Answer 4

so that oxygen binds to the protein cooperatively, yielding a sigmoidal binding curve.

Question 5

alter hemoglobin’s O2-binding affinity.

Answer 5

Bohr effect and BPG

Question 6

has low affinity for oxygen

Answer 6

hemoglobin

Question 7

has high affinity for oxygen

Answer 7

myoglobin

Question 8

what has better oxygen delivery hemoglobin or myoglobin

Answer 8

hemoglobin

Question 9

prevents this oxidation and makes it possible for O2 to bind reversibly to the heme group

Answer 9

The protein portion of myoglobin and hemoglobin

Question 10

CO has what affinity for hemoglobin than does O2.

Answer 10

200-fold greater

Question 11

its major physiological role is to facilitate oxygen diffusion in muscle.

Answer 11

myoglobin

Question 12

The rate at which O2 can diffuse from the capillaries to the tissues is limited by its what

Answer 12

low solubility in aqueous solution

Question 13

which is present mainly in brain, retina, and endocrine tissues

Answer 13

neuroglobin

Question 14

which occurs in most tissues.

Answer 14

cytoglobin

Question 15

occurs when ligands interact independently with their binding sites.

Answer 15

hyperbolic binding curve

Question 16

Animals that are too large (>1 mm thick) for simple diffusion to deliver sufficient oxygen to their tissues have circulatory systems containing what

Answer 16

hemoglobin

Question 17

what makes hemoglobin a better O2 carrier

Answer 17

high concentration of BPG
High P50

Question 18

what happens to the BPG concentration in low O2 environments such as in high altitudes

Answer 18

increases

Question 19

O2 binding to hemoglobin is described by a

Answer 19

sigmoidal (S-shaped) curve

Question 20

This permits the blood to deliver much more O2 to the tissues

Answer 20

sigmoidal (S-shaped) curve

Question 21

increases with the degree of cooperativity of a reaction

Answer 21

quantity n, the Hill constant

Question 21

For normal human hemoglobin, the Hill constant is between

Answer 21

2.8 - 3.0

Question 22

Oxygen Binding to Hemoglobin Triggers a Conformational Change from what to what

Answer 22

T to R

Question 23

are conformations of deoxyhemoglobin & oxyhemoglobin respectively

Answer 23

T & R states

Question 24

has low O2 affinity

Answer 24

T state of hemoglobin

Question 25

tears away the ion pairs formed by C-
terminal residues of each subunit in a process that is driven by the energy of formation of the Fe—O2 bonds.

Answer 25

T —> R transition

Question 26

Increasing the pH stimulates hemoglobin to bind more O2 at lower O2 pressures.

Answer 26

The Bohr Effect Enhances Oxygen Transport

Question 27

has important physiological functions in transporting O2 from the lungs to respiring tissue and in transporting the CO2 produced by respiration back to the lungs.

Answer 27

The Bohr effect

Question 28

CO2 also modulates O2 binding to hemoglobin by combining reversibly with the N-terminal amino groups of blood proteins to form

Answer 28

carbamates

Question 29

binds more CO2 and transport it to lung.

Answer 29

The T (deoxy) form of hemoglobin

Question 30

decreases hemoglobin’s oxygen affinity by keeping it in the deoxy conformation.

Answer 30

BPG

Question 31

can be adjusted more rapidly than hemoglobin can be synthesized for example increases as a result of high-altitude adaptation.

Answer 31

BPG concentration

Question 32

Fetal hemoglobin has low what?

Answer 32

BPG Affinity

Question 33

a molecule that binds to hemoglobin in red blood cells, affecting its oxygen affinity

Answer 33

BPG

Question 34

is an oligomer of symmetrically related subunits.

Answer 34

allosteric protein

Question 35

Each oligomer can exist in two conformational states called what

Answer 35

designated R and T

Question 36

Only the what alters the affinity for the ligand.

Answer 36

conformational change

Question 37

The molecular symmetry of the protein is what during the conformational change

Answer 37

conserved

Question 38

The subunits must therefore change conformation in a what manner

Answer 38

concerted

Question 39

ligand binding induces a conformational change in the subunit to which it binds, and cooperative interactions arise through the influence of those conformational changes on neighboring subunits.

Answer 39

sequential model

Question 40

deoxyhemoglobin S forms insoluble filaments that deform erythrocytes.

Answer 40

sickle-cell hemoglobin (hemoglobin S)

Question 41

The immune response is triggered by the presence of a foreign macromolecule, often a protein or carbohydrate, known as an

Answer 41

antigen

Question 42

B cells display what on their surfaces.

Answer 42

immunoglobulins (antibodies)

Question 43

the most common immunoglobulin

Answer 43

IgG

Question 44

The ability for the basic immunoglobulin structure to recognize a variety of antigens resides in three loops in the variable domain called

Answer 44

hypervariable

Question 45

divalent molecules meaning they can bind two identical antigens simultaneously

Answer 45

immunoglobulins

Question 46

allows antibodies to cross-link antigens to form an extended lattice, which hastens the removal of the antigen and triggers B cell proliferation.

Answer 46

Divalent binding

Question 47

Loses Its Tolerance in Autoimmune Diseases.

Answer 47

Immune System