Terminology

2,3-bisphosphoglycerate (BPG) - An allosteric effector of hemoglobin in mammals. It binds between the chains and reduces affinity of hemoglobin for oxygen. It is implicated both in adaptation to high altitudes and in the stronger affinity of fetal hemoglobin for oxygen than adult hemoglobin (Figure 7.18).
Aerobic Metabolism - Metabolism involving oxygen.
Aflatoxin A - Mutagen in moldy nuts or grains that alkylates compounds. It modifies guanine and causes missense mutations (Table 7.1).
AIDS - Disease ultimately resulting from infection with HIV virus (Figure 7.37b).
Allosteric Effectors - Molecules which promote allosteric transitions in a protein.
Allostery - With respect to proteins, a phenomenon that the activity of one part of an enzyme (such as an active site) is influenced by the binding of an effector to a different part of the enzyme.
-Thalassemia - A condition in which globin genes of hemoglobin are lost. The condition is serious only if three or more of the four globin genes are missing.
Antigen - A substance that can elicit a specific immune response (Figure 7.29).
Antigenic Determinant - A specific part of an antigen that elicits antibody production.
Association constant/Affinity constant - Given by 'K', in the oxygen binding reaction of myoglobin, K is calculated as the concentration of myoglobin bound to oxygen divided by the product of the free oxygen concentration and the free myoglobin concentration.
B cells - Lymphatic cells produced by B lymphocytes in the humoral immune response (Figure 7.31).

Benzo[a]pyrene - A mutagen found in smoke that intercalates in DNA and causes frameshift mutations (Table 7.1).
-Thalassemia - A condition in which the beta globin gene is lost or cannot be expressed. Individuals homozygous for this defect must rely on production of the fetal globin and consequently die before reaching maturity.
Bicarbonate Reaction - A reaction occurring in erythrocytes as a result of accumulation of carbon dioxide: CO 2 + H 2 O <=> HCO 3- + H+
Bohr Effect - An effect in which the oxygen affinity of hemoglobin is reduced as a consequence of a pH drop (Figure 7.16).
Carbon monoxide - A molecule about the same shape as oxygen, which is bound more tightly than oxygen to myoglobin and hemoglobin. Is a toxic gas that block respiration.
Cellular Immune Response - One facet of the immune response that is brought about by lymphatic cells called T lymphocytes, which bear immunoglobulin-like molecules on their surfaces, recognize and kill foreign or aberrant cells.
Concerted Model of Allosterism - A model of allosterism consistent with the theory of Monod, Wyman, and Changeux in which the hemoglobin tetramer exists in an equilibrium between two forms, a deoxy (T) state, in which all subunits are in the weak-binding conformation, and the oxy (R) state, in which they are all in the strong-binding form. Partial oxygenation shifts the equilibrium between the two states toward the R state. The shift is a concerted one (Figure 7.10).
Conservative Amino Acid Changes - Mutations in coding sequences for proteins which convert a codon for one amino acid to a codon for another amino acid with very similar chemical properties.
Constant Domain - A part of an immunoglobulin identical in all antibodies of a given class (Figure 7.32).
Cooperative Binding - A phenomenon in which a protein with multiple binding sites for a compound exhibits increased affinity for binding of the compound as more of it is bound (Figure 7.10).
Cooperative Transition - A transition in a multipart structure such that the occurrence of the transition in one part of the structure makes the transition likelier to happen in other parts (Figure 7.15).
Dimer - A complex of two units.
Dimethyl Nitrosamine - A mutagen in some prepared foods that methylates compounds, modifies bases, and yields missense mutations (Table 7.1).
Diploid - For a cell or an organism, the possession of two homologous sets of chromosomes per nucleus (with the possible exception of sex chromosomes, which may be present in only one copy).
Exons - A region in the coding sequence of a gene that is translated into protein (as opposed to introns, which are not). The name comes from the fact that exons are the only parts of an RNA transcript that are seen outside the nucleus of eukaryotic cells (Figure 7.20).
Fab Fragments - An antibody fragment produced by proteolysis in which the hinge region is cleaved to produce molecules with only one binding site each (Figure 7.32).
Frameshift Mutations (Gibberish Mutations) - A type of mutation in the coding sequence for a protein in which an insertion or deletion is made that changes the reading frame of the sequence for the protein (Figure 7.21).
Genetic Recombination - A process in which genes or DNA sequences are cut and recombined together.
Haploid - For a cell or an organism, the possession of only one copy of each chromosome per nucleus.
Heme - Prosthetic oxygen binding site of globin (and other) proteins. Is a complex of protoporphyrin IX and Fe (II). Carries oxygen in globin proteins (Figure 7.4, Figure 7.5).
Hemerythrin - An oxygen binding protein containing iron used by some invertebrates. It is not related to the globins.
Hemocyanin - An oxygen binding protein, which contains copper, found in mollusks and some arthropods.
Hemoglobin - Four-subunit oxygen carrying protein in higher animals (Figure 7.3).
Hemoglobin Hammersmith - A condition involving a mutated hemoglobin which has a destabilized tertiary structure and is frequently unable to hold the heme effectively (Table 7.2).
Hemoglobin St. Lukes - A condition involving a mutated hemoglobin which has a destabilized hemoglobin tetramer (Table 7.2).
Hemoglobins M - A condition involving a mutated hemoglobin which tends to be readily oxidized to methemoglobin (Table 7.2).
Heterodimer - A complex of two units in which the two units are not identical.
Heterozygous - In a diploid organism, the possession of two different alleles for a given gene (as opposed to two copies of the same allele) (Figure 7.26).
Hill Coefficient - The maximum slope of a Hill plot, n H (Figure 7.9).
Hill Plot - A graph of log[/(1-)] versus log P O 2 where = sites of a binding protein occupied/total available sites (Figure 7.9).
HIV - Virus implicated in causing AIDS (Figure 7.37b).
Homodimer - A complex of two units in which both units are identical.
Homozygous - In a diploid organism, the possession of two identical alleles for a given gene (Figure 7.26).
Humoral Immune Response - One facet of the immune response that is brought about by lymphatic cells called B lymphocytes, which synthesize specific immunoglobulin molecules that are excreted from the cell and bind to the invading substance. This binding either precipitates the foreign substance or marks it for destruction by cells called macrophages.
IgA - An immunoglobulin found in bodily secretions, including saliva, sweat, tears, and along the walls of the intestines. It is the major antibody of colostrum, the initial secretion from a mother's breasts after birth (Table 7.3).
IgD An immunoglobulin found on the surface of B cells (Table 7.3).
IgE An immunoglobulin associated with some of the body's allergic responses (Table 7.3).
IgG An immunoglobulin also known as gamma-globulin. It is the most abundant of circulating antibodies (Table 7.3).
IgM An immunoglobulin produced during the early response to an invading microorganism that is the largest immunoglobulin. It contains 5 Y-shaped units of two light and two heavy chains each (Table 7.3).
Immune System Memory - A phenomenon in which an initial exposure to a given antigen results in rapid and much more massive production of specific antibodies upon second exposure.
Immunoglobulin Fold - Common structural domain of the antibodies of both the humoral response and the cellular response. The structure probably represents the primitive structural element in the evolution of the immune response (Figure 7.36).
Inositol Hexaphosphate - An allosteric effector of hemoglobin in birds It binds between the chains and reduces affinity of hemoglobin for oxygen (Figure 7.17).
Intron(s) - A region in the coding sequence of a gene that is not translated into protein. Introns are common in eukaryotic genes but are rarely found in prokaryotes. They are excised from the RNA transcript before translation (Figure 7.20).
Killer T Cells - Major participants in the cellular immune response - also called cytotoxic T cells .
Major Histocompatibility Complex Proteins (MHC proteins) - A class of immunoglobulin-like molecules on the surface of infected cells targeted by T cells for attachment (Figure 7.35).
Methemoglobin - An oxidized form of hemoglobin containing Fe (III), which cannot bind oxygen. Can be formed by allowing hemoglobin to be exposed to air, outside the cellular environment.
Metmyoglobin - An oxidized form of myoglobin containing Fe (III), which cannot bind oxygen. Can be formed by allowing myoglobin to be exposed to air, outside the cellular environment.
Missense Mutation - A mutation in which a codon for one amino acid in a protein sequence is converted to a codon for another amino acid (Figure 7.21).
Multistate Model of Allosterism - A complex model of oxygen binding with a concerted switch between binding states consistent with the Monod, et al., model, but with more than two states of binding.
Mutagen - Substance that produces mutations in DNA (Table 7.1).
Mutation - A change in the sequence of DNA.
Myoglobin - Single subunit oxygen storage protein (Figure 7.3).
Nitrous Acid - A mutagen in some prepared foods that deaminates C to U, leading to missense mutations (Table 7.1).
Nonsense Mutation - A mutation in which a codon for an amino acid in a protein sequence is converted to a STOP codon (Figure 7.21).
P 50 - The partial pressure of a gas causing half saturation of a binding protein for that gas.
Perforin - Protein released by T cells in response to recognition of proteins of the major histocompatibility complex (MHC). The protein forms pores in the plasma membrane of the cell being attacked, allowing critical ions to diffuse out, thereby killing the cell.
Polyploid - For a cell or an organism, the possession of more than two homologous sets of chromosomes per nucleus.
Porphyrins - A class of compounds found in chlorophyll, the cytochrome proteins, blood, and some natural pigments. They are responsible for the red color of blood and the green color of plants (Figure 7.4).
pre-mRNA - A messenger RNA (mRNA) molecule that has not been processed to remove introns from the sequence (Figure 7.20).
Primary Structure - For a nucleic acid or a protein, the sequence of the bases or amino acids in the polynucleotide or polypeptide.
Protoporphyrin IX - A tetrapyrrole ring in the globin family which chelates Fe(II) and carries oxygen (Figure 7.4).
Quaternary Structure - For a protein, the level of structure that results when separate, folded polypeptide chains (subunits) associate in a specific way to produce a complete protein.
Secondary Structure - Local folding of the backbone of a linear polymer to form a regular, repeating structure. The B- and Z-forms of the DNA helix and the -helix and -sheet structures of polypeptides are examples.
Sequental Model of Allosterism - A model to explain cooperativity (after that of Koshland, Nemethy, and Filmer) in which the presence of a subunit of hemoglobin carrying oxygen favors formation of the strong-binding state of an adjacent subunit whose oxygen binding site is not yet filled. Such models are characterized by the existence of molecules with some subunits in the weak state, some in the strong (Figure 7.10).
Sickle Cell Hemoglobin - A condition involving a mutated hemoglobin in which red blood cells adopt an elongated sickle shape at low oxygen concentrations.
Somatic Mutations - Mutations that occur outside of the germ cells and are thus not inherited.
T cells - Lymphatic cells produced by the thymus participating in the cellular immune response (Figure 7.30).
Tertiary Structure - Large-scale folding structure in a linear polymer that is at a higher order than secondary structure. For proteins and RNA molecules, the tertiary structure is the specific three-dimensional shape into which the entire chain is folded.
Tetrapyrrole Ring System - General name of chemical group which chelates Fe(II) in globin family. Protoporphyrin IX is one such compound.
- The fraction of all binding sites of a binding protein that are occupied - calculated as (sites of a binding protein occupied)/(total available sites).
Ultraviolet Light - A damaging form of radiation in sunlight that causes formation of pyrimidine dimers.
Variable Domain - A part of an immunoglobulin that varies in amino acid sequence and tertiary structure from one antibody to another (Figure 7.32).