Ch 5

Question 1

Myoglobin

Answer 1

(Monomer) facilitates oxygen diffusion in muscle tissue

Question 2

Hemoglobin

Answer 2

(Tetramer) responsible for oxygen transport in the bloodstream

Question 3

Prosthetic group

Answer 3

A non amino acid component that is part of the structure of a protein

Question 4

Apoprotein

Answer 4

A protein without its prosthetic group

Question 5

Holoprotein

Answer 5

Protein combined with its prosthetic group

Question 6

Heme

Answer 6

The prosthetic group found in myoglobin and hemoglobin
Consists of a complex organism ring structure, protoporphyrin with its bound iron in its ferrous state

Question 7

Perpendicular coordination bonds of iron

Answer 7

Proximal his residue
Binding site for molecular oxygen

Question 8

Globins

Answer 8

Widespread protein family
Tertiary structure with eight alpha helical segments connected by bends

Question 9

Neuroglobin

Answer 9

Monomeric, expressed largely in neurons to protect the brain from low O2 or restricted blood supply

Question 10

Cytoglobin

Answer 10

Monomeric, regulates levels of nitric oxide, a localized signal for muscle relaxation

Question 11

Ligand

Answer 11

Molecule that binds to another (usually larger) molecule

Question 12

Association constant

Answer 12

Type of equilibrium constant that provides a measure of the affinity of the ligand for the portein

Question 13

What does a high value of Ka mean?

Answer 13

Higher affinity of the ligand for the protein

Question 14

Kd

Answer 14

A reaction in which the uncomplexed or dissociated species are the product
Lower kd means higher affinity for the protein

Question 15

Greater affinity for ligand

Answer 15

Lower kd values and higher ka values

Question 16

What affects binding?

Answer 16

Protein structure and conformational changes

Question 17

R state

Answer 17

O2 has higher affinity for hemoglobin

Question 18

T state

Answer 18

More stable when O2 is absent, predominant conformation of deozyhemoglobin

Question 19

Sigmoid binding curve

Answer 19

Describes a transition from a low affinity state (t-state) to a high affinity state (r state) as more O2 molecules aer bound

Question 20

Allosteric

Answer 20

The binding of a ligand to one site affects the binding properties of another site in the same proyein

Question 21

Modulator

Answer 21

Ligands that bind to a protein and reveal a new shape/induce conformational change, they may be inhibitors or activators

Question 22

Homotrophic

Answer 22

Ligand and modulator are the same molecule and bind to allosteric state

Question 23

Allosteric binding

Answer 23

The binding of one ligand affect the affinities of any remaining unfilled bonding sites

Question 24

Cooperative binding

Answer 24

In a multi subunit protein, a conformational change in one subunit often affects the conformation of other subunits

Question 25

Conformational Changes in hemoglobin

Answer 25

- Alpha beta subunit pairs past each other and rotate - the pocket between the beta subunits narrow - some ion pairs that stabilize the t state break and some new ones form - other stabilizing factors: hydrophobic effect and hydrogen bonds

Question 26

Hill coefficient

Answer 26

Measures the degree of cooperactivity NH > 1 indicates positive cooperactivity NH < 1 indicated negative cooperactivity

Question 27

Positive cooperactivity

Answer 27

The ligand causes other ligands to bind more readily

Question 28

Negative cooperactivity

Answer 28

The ligand impedes the binding of others

Question 29

MWC model = concerted model

Answer 29

- all subunits in the same conformation - ligand binds more tightly to the R state

Question 30

Sequential model

Answer 30

- each subunit can be in either conformation - equilibrium is altered as additional ligands are bound, progressively favoring the R state

Question 31

Systems that deal with H+ and CO2

Answer 31

Bicarbonate buffer system Hemoglobin

Question 32

Bicarbonate Buffer System

Answer 32

- carbonic anhydrase catalyzes the bidirectional conversion of carbon dioxide and water into bicarbonate and protons - exchange of CO2 in the blood with atmospheric CO2 in the air spaces - excretion of HCO3 or retention of HCO3

Question 33

Bohr effect

Answer 33

Binding and release of oxygen is profoundly influenced by pH and CO2 concentration Oxygen bind better when less H+ are present

Question 34

2,3 BPG

Answer 34

Reduces the affinity of hemoglobin for oxygen (inverse relationship)

Question 35

Where does BPG bind?

Answer 35

BPG binds to the cavity between the beta subunits and the T state. The cavity is lined with positively charged residues.

Question 36

Sickle cell anemia

Answer 36

Single amino acid substitution of glu to val where beta chains produce a hydrophobic patch that causes molecules to aggregate into strands that align into insoluble fibers

Question 37

Hemoglobin

Answer 37

Releases the oxygen to permit aerobic respiration in tissues to provide energy to power functions of an organism (metabolism(

Question 38

What is the immune response?

Answer 38

- a coordinated set of interactions among many classes of proteins, molecules, and cell types - distinguishes molecular self from nonself and destroys nonself - eliminates viruses, bacteria, and other pathogens and molecules

Question 39

Leukocytes

Answer 39

White blood cells, including macrophages and lymphocytes

Question 40

Innate immune system

Answer 40

Directed at bacterial infections and extracellular viruses

Question 41

Adaptive cellular immune system

Answer 41

Destroys infected host cells, parasites, and foreign tissues

Question 42

Antibodies

Answer 42

Bind bacteria, viruses, or large molecules identified as foreign and target them for destruction Produced by B lymphocytes or B cell

Question 43

Immunoglobulin G

Answer 43

Major class of antibodies, 2 heavy chains and 2 light chains

Question 44

Antigen

Answer 44

The foreign particle capable of eliciting an immune response - can be a virus, bacterial cell wall, or an individual protein or other macromolecule

Question 45

Induced fit

Answer 45

Conformational changes in the antibody and/or antigen allow the complementary groups to interact fully

Question 46

Happens

Answer 46

Small molecules that can elicit and immune response when covalently attached to large proteins

Question 47

Antigenic determinant or epitope

Answer 47

An antigen determinant; the particular chemical group or groups in a molecule (antigen) to which a given antibody binds

Question 48

Epitope tag

Answer 48

A highly antigenic amino acid sequence added to the protein coding sequence of cloned genes that is recognized by commercially available antibodies

Question 49

Polyclonal antibodies

Answer 49

- produced by injecting a protein into an animal - contain a mixture of antibodies that recognize different parts of the protein (different epitopes)

Question 50

Monoclonal antibodies

Answer 50

- synthesized by a population of identical B cells (a clone) - homogeneous, all recognizing the same epitope

Question 51

Western blot

Answer 51

Uses antibodies to detect a protien