Lehninger Ch 5

Question 1

Ligand

Answer 1

A small water-insoluble biomolecule generally containing fatty acids, sterols, or isopreniod compounds (a ligand is a protein)

Question 2

Binding site

Answer 2

The crevice or pocket on a protein in which the ligand binds

Question 3

Induced fit

Answer 3

An enzyme conformation change in response to substrate binding that renders the enzyme catalytically active; also denotes a conformation change in any macromolecule in response to ligand binding, such that the binding site better conforms to the shape of the ligand

Question 4

Hemoglobin

Answer 4

A heme protein in erythrocytes; functions in oxygen transport

Question 5

Heme

Answer 5

The iron-porphyrin prosthetic group of heme proteins

Question 6

Porphyrin

Answer 6

A complex nitrogenous compound containing four substituted pyrroles covalently joined in a ring; often complexed with a central metal atom

Question 7

Globins

Answer 7

Are a widespread family of oxygen-binding proteins. Commonly found in eukaryotes of all classes, as well as in archea and bacteria. All evolved from a common ancestral protein. Their tertiary structure is highly conserved, made up of eight a-helical segments connected by bends

Question 8

Globin fold

Answer 8

Their tertiary structure is highly conserved, made up of eight a-helical segments connected by bends. This folding pattern, illustrated by myoglobin constitutes a structural motif known as the globin fold

Question 9

Equilibrium expression

Answer 9

The reversible binding of a protein (P) to a ligand (L)

Question 10

Association constant, Ka

Answer 10

Describes the equilibrium between the complex and the unbound components of the complex. The association constant provides a measure of affinity of the Ligand

Question 11

Dissociation constant, Kd

Answer 11

The reverse of the association constant, high Ka means low Kd
The reciprocal of Ka and has units of molar concentration (M)

Question 12

Allosteric protein

Answer 12

An allosteric protein is one in which binding of a ligand to one site affects the binding properties of another site on the same protein ex hemoglobin is in T state becomes more R state the more oxygen binds

Question 13

Modulator

Answer 13

Allosteric proteins are those having “other shapes” or conformations, induced by the binding of ligands referred to as modulators. The conformation changes induced by the modulator(s) interconvert more-active and less-active forms of the protein

Question 14

Homotrophic

Answer 14

When the normal ligand and the modulator are identical, the interaction is termed homotrophic

Question 15

Heterotrophic

Answer 15

When the modulator is a molecule other than the normal ligand.

Question 16

Hill Equation

Answer 16

Kd=[L]^n with subscript 0.5
n= binding sites

Question 17

Hill Coefficient

Answer 17

Is the measure of the degree of cooperatively; nH greater than 1 indicates positive cooperative binding

Question 18

Bohr effect

Answer 18

The binding of H+ and CO2 is inversely related to the binding of oxygen. At relatively low pH and high CO2 concentration of peripheral tissues, the affinity of hemoglobin for oxygen decreases as H+ and CO2 are bound, and O2 is released to the tissues. Conversely, in the capillaries of the lung, as CO2 is excreted and the blood pH consequently rises, the affinity of hemoglobin for oxygen increases and the protein binds more O2 for transport to the peripheral tissues. This effect of pH and CO2 concentration on the binding and release of oxygen by hemoglobin is called the Bohr Effect

Question 19

Immune response

Answer 19

On a physiological level, the immune response is an intricate and coordinated set of interactions among many classes of proteins, molecules, and cell types

Question 20

Lymphocytes

Answer 20

Type of white blood cells, all of which develop from undifferentiated stem cells in the blood marrow

Question 21

Antibody

Answer 21

At the heart of the humoral immune response are soluble proteins called antibodies or immunoglobulins; A defense protein synthesized by the immune system of vertebrates and circulated in the blood

Question 22

Immunoglobulin (Ig)

Answer 22

An antibody protein generated against and capable of binding specifically to an antigen

Question 23

B lymphocytes

Answer 23

One of a class of blood cells (lymphocytes), responsible for the production of circulating antibodies

Question 24

T lymphocytes

Answer 24

One of a class of blood cells (lymphocytes) of thymic origin, involved in cell-mediated immune reactions

Question 25

Antigen

Answer 25

A molecule capable of eliciting the synthesis of specific antibody in vertebrates

Question 26

Epitope

Answer 26

An antigenic determinant; the particular chemical group or groups in a macromolecule (antigen) to which a given antibody binds (Where T cells bind)

Question 27

Hapten

Answer 27

A small molecule that, when linked to a larger molecule, elicits an immune response

Question 28

Immunoglobulin fold

Answer 28

The constant domains in Immunoglobulin that have a characteristic structure; a well-conserved structural motif in the all - beta class of proteins

Question 29

Polyclonal antibodies

Answer 29

A heterogeneous pool of antibodies produced in an animal by different B lymphocytes in response to an antigen. Different antibodies in the pool recognize different parts of the antigen

Question 30

Monoclonal antibodies

Answer 30

Antibodies produced by a cloned hybridoma cell, which are therefore identical and directed against the same epitope of the antigen

Question 31

Immunoblotting or Western Blotting

Answer 31

A technique using antibodies to detect the presence of a protein in a biological sample after the proteins have been separated by gel electrophoresis, transferred to a membrane, and immobilized

Question 32

Myosin

Answer 32

A contractile protein; the major component of the thick filaments of muscle and other actin-myosin systems

Question 33

Actin

Answer 33

A protein that makes up the thin filaments of muscle; also important component of the cytoskeleton of many eukaryotic cells

Question 34

Myofibril

Answer 34

A unit of thick(darker A bands stretch thick and where the thin and thick intersect) and thin (I bands-bisecting is a thin structure called the Z band) filaments of muscle fibers

Question 35

Sarcomere

Answer 35

The entire contractile unit, consisting of bundles of thick filaments interleaved at either end with bundles of thin filaments is called the sacromere
A system of flat membranous vesicles called the sarcoplasmic reticulum surrounds each myofibril