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

(48 cards)

1
Q

exhibits a hyperbolic O2-binding curve.

A

Myoglobin

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2
Q

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

A

Hemoglobin

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3
Q

triggers conformational changes in hemoglobin

A

oxygen binding

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4
Q

why does oxygen binding trigger conformational changes in hemoglobin

A

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

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5
Q

alter hemoglobin’s O2-binding affinity.

A

Bohr effect and BPG

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6
Q

has low affinity for oxygen

A

hemoglobin

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7
Q

has high affinity for oxygen

A

myoglobin

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8
Q

what has better oxygen delivery hemoglobin or myoglobin

A

hemoglobin

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9
Q

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

A

The protein portion of myoglobin and hemoglobin

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10
Q

CO has what affinity for hemoglobin than does O2.

A

200-fold greater

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11
Q

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

A

myoglobin

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12
Q

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

A

low solubility in aqueous solution

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13
Q

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

A

neuroglobin

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14
Q

which occurs in most tissues.

A

cytoglobin

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15
Q

occurs when ligands interact independently with their binding sites.

A

hyperbolic binding curve

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16
Q

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

A

hemoglobin

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17
Q

what makes hemoglobin a better O2 carrier

A

high concentration of BPG
High P50

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18
Q

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

A

increases

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19
Q

O2 binding to hemoglobin is described by a

A

sigmoidal (S-shaped) curve

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20
Q

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

A

sigmoidal (S-shaped) curve

21
Q

increases with the degree of cooperativity of a reaction

A

quantity n, the Hill constant

21
Q

For normal human hemoglobin, the Hill constant is between

22
Q

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

23
Q

are conformations of deoxyhemoglobin & oxyhemoglobin respectively

24
has low O2 affinity
T state of hemoglobin
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.
T ---> R transition
26
Increasing the pH stimulates hemoglobin to bind more O2 at lower O2 pressures.
The Bohr Effect Enhances Oxygen Transport
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.
The Bohr effect
28
CO2 also modulates O2 binding to hemoglobin by combining reversibly with the N-terminal amino groups of blood proteins to form
carbamates
29
binds more CO2 and transport it to lung.
The T (deoxy) form of hemoglobin
30
decreases hemoglobin's oxygen affinity by keeping it in the deoxy conformation.
BPG
31
can be adjusted more rapidly than hemoglobin can be synthesized for example increases as a result of high-altitude adaptation.
BPG concentration
32
Fetal hemoglobin has low what?
BPG Affinity
33
a molecule that binds to hemoglobin in red blood cells, affecting its oxygen affinity
BPG
34
is an oligomer of symmetrically related subunits.
allosteric protein
35
Each oligomer can exist in two conformational states called what
designated R and T
36
Only the what alters the affinity for the ligand.
conformational change
37
The molecular symmetry of the protein is what during the conformational change
conserved
38
The subunits must therefore change conformation in a what manner
concerted
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.
sequential model
40
deoxyhemoglobin S forms insoluble filaments that deform erythrocytes.
sickle-cell hemoglobin (hemoglobin S)
41
The immune response is triggered by the presence of a foreign macromolecule, often a protein or carbohydrate, known as an
antigen
42
B cells display what on their surfaces.
immunoglobulins (antibodies)
43
the most common immunoglobulin
IgG
44
The ability for the basic immunoglobulin structure to recognize a variety of antigens resides in three loops in the variable domain called
hypervariable
45
divalent molecules meaning they can bind two identical antigens simultaneously
immunoglobulins
46
allows antibodies to cross-link antigens to form an extended lattice, which hastens the removal of the antigen and triggers B cell proliferation.
Divalent binding
47
Loses Its Tolerance in Autoimmune Diseases.
Immune System