Acid:  A substance that increases the hydrogen ion concentration in a solution.

Activation energy:  The initial investment of energy in a reaction.  Activation energy (Ea) is required to energize the bonds of the reactants to an unstable transition state that precedes the formation of products.

Active Site:  That specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds.

Adaptive radiation:  The emergence of numerous species from a common ancestor introduced to an environment presenting a diversity of new opportunities and problems.

Adaptive Traits: Any aspect of form, function, or behavior that helps an organism survive and reproduce under a given set of environmental conditions.

Adenine: A purine; a nitrogen-containg base found in nucleotides.  Always found bound to thymine in DNA.

Aldehyde: An organic molecule with a carbonyl group located at the end of the carbon skeleton. R-HC=O.

Allantois: A vascularized extraembryonic membrane; in reptiles and birds, it functions in excretion and respiration in placental mammals, it functions in oxygen transport by way of the umbilical cord.

Alleles: one of two or more alternative forms of a gene at a given location on a chromosome.

Allosteric Site:  A specific receptor site on an enzyme molecule remote from the active site.  Molecules bind to the allosteric site and change the shape of the active site, making either more or less receptive to the substrate.

Alpha (a) Helix: A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bondng structure.

Alternation of Generations:  Occurences of multicellular diploid form, the sporophyte, with a multicellular haploid form, the gametophyte.

Amino Acids: Organic molecules possessing both carboxyl and amino groups and serving as the monomers of proteins.

Amino Group: A functional group that consists of a nitrogen atom bonded to two hydrogen atoms.  It can act as a base in solution, accepting a hydrogen ion and acquiring a charge of +1.

Amnion: In land vertebrate, an extraembryonic membrane in the form of a fluid filled sac around the embryo; it absorbs shocks and keeps the embryo from drying out.

Anabolic Pathways: Metabolic pathways that build up complex molecules from simpler compounds, requiring energy input usually provided by catabolism.

Analogy:  The similarity of structure between two species that are not closely related; attributable to convergent evolution.

Anaphase: The stage of mitosis when sister chromatids of each chromosome separate and move to opposite poles of the spindle.

Angiosperms:  Flowering plants, which form seeds inside protective chambers called ovaries.

Anion:  A negatively charged ion.

Anterior:  The head end of a bilaterally symmetrical animal.

Anther: The pollen bearing part of the male reproductive structure in flowering plants.

Anticodon:  A specialized base triplet on one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.

Antigen:  A foreign macromolecule that does not belong to the host organism and that elicits an immune response.

Aqueous Solution:  A solution in which water is the solvent.

Archaebacteria:  The more ancient of the two major lineages of prokaryotes, represented today by a few groups of bacteria inhabiting extreme environments.

Archaeopteryx: A transtional form on (or very near) the evolutionary road leading from reptiles to birds.

Arteries:  Vessels that carry blood away from the heart to organs througout the body.

Arterioles:  Branches of the arteries present within organs.

Artificial Selection:  The selective breedng of domesticated plants and animals to encourate the occurence of desirable traits.

Asexual Reproduction: Mode of reproduction in which a single parent that produces genetically identical offspring by budding or division of a single cell or the entire organism into two or more parts.

A-Site:  The binding site on a ribosome that holds the tRNA carrying the next amino acid to be added to a growing polypeptide chain.

Assymetric Carbon:  A carbon atom covalently bonded to four different atoms or groups of atoms.
 
Atomic Mass:  The number of protons and neutrons in the nucleus of an atom.

Atomic Number:  The number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the elemental symbol.

ATP (adenosine triphosphate):  An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed.  This energy is used to drive endergonic reactions in cells.

ATPases:  A group of enzymes tha function in producing or using ATP.

Atria:  The chambers of the heart that receive blood returning to the heart.

Autosomes:  Any of those chromosomes that are of the same number and kind in both males and females of the species.

Autotroph:  An organism able to build all the organic molecules it requires using carbon dioxide  (present in air and in water) and energy from the physical environment.  Photosynthetic autotrophs use sunlight; chemosynthetic autotrophs extract energy from chemical reactions involving inorganic substances.  compare heterotroph.
 

Biochemistry:

Blastocyst: In mammalian development, a modified blastula stage consisting of a hollow ball of surface cells and an inner cell mass.

Budding:  The developing shoot of mostly meristematic tissue; often protected by a covering of modified leaves.

Carbonyl: A functional group found in aldehydes and ketones that consists of a carbon atom joined to an oxygen atom by a double bond.

Carboxyl:  A functional group present in organic acids, consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group.

Carpals:

Catabolic Pathways: break complex molecules into simpler compounds, releasing energy in the process.

Cellulose:

Cell Membrane:

Cell Wall:

Centromere: A small, constricted region of a chromosome having attachment sites for microtubules that help move the chromosome during nuclear division.

Centrifuge: a machine that spins samples at a high speed and forces the settling of suspended material.

Cervix: The junction of the vagina and uterus in mammals.

Chemical Energy: a form of potential energy stored in the molecular structure.

Cholesterol:

Chorion: The outer layer of the embryonic sac of a mammal consisting of both trophoderm and mesoderm elements and the outermost extraembryonic membrane in birds and reptiles.

Chromosome: In eukaryotes, a DNA molecule and many associated proteins.  A chromosome that has undergone duplication prior to nuclear division consists of two DNA molecules and associated proteins; the two are called sister chromatids.  A bacterial chromosome does not have a comparable profusion of proteins associated with its DNA.

Chromatids: The name applied to each of the two parts of a duplicated eukaryotic chromosome for as long as the two parts remain attached at the centromere.  Each chromatid consists of a DNA double helix and associated proteins, and it has the same gene sequence as its "sister" chromatids.

Cleavage: Stage of animal development when mitotic cell divisions convert a zygote to a ball of cells, the blastula.  Different cytoplasmic components end up in different daughter cells, and this cytoplasmic location.

Comparative Biochemistry:

Complementary:

Convergent Evolution:

Corpus Luteum: The mass of yellow secretory cells formed in the cavity of a a ruptured Graafian follicle.  Responsible for maintaining the level of progesterone after implantation of the embryo.

Covalent Bonds:

Crossing over:  During prophase I of meiosis, an event in which non sister chromatids of a pair of homologous break at exchange corresponding segments at the breakage points.  As a result, new combinations of alleles replace old ones in a chromosome.

Cytokinesis: The actual splitting of a parental cell into two daughter cells; also called cytoplasmic division.

Cytoplasm: All cellular parts, particles and semi fluid substances enclosed by the plasma  membrane except the nucleus( in eukaryotes) or the nucleoid (in prokaryotes).

Cytosine:

Dehydration Synthesis:

Deletions (DNA): Loss of chromosome segment, nearly always resulting in genetic disorder.

Denature:

Deoxyribose:

Differentiation: Of the cells of multicellular organisms, differences in composition, structure, and function that arise through selective gene expression.  All the cells inherit the same genes but become specialized by activating or suppressing some fraction of those genes in different ways.

Dihybrid Cross: An experimental cross between two organisms, each of which breed true (is homozygous) for forms of two traits that are distinctly different from those displayed by the other organism.  For each trait, the first generation offspring inherit a pair of nonidentical alleles.

Diploid: Of sexually reproducing species, having two chromosomes of each type (that is, homologous chromosomes) in somatic cells.  Except for sex chromosomes, the two homologues of a pair resemble each other in length, shape, and which genes they carry.

Directional Selection:

Disaccharides:

Disruptive Selection:

Disulfide Bridges:

Divergence:

DNA: (Deoxyribonucleic acid)  Usually, two strands of nucleotides twisted together in the shape of a double helix.  The nucleotides differ only their nitrogen containing vases (adenine, guanine, thymine, cytosine), but which ones follow others in a DNA strand represents instructions for assembling proteins, and ultimately new organisms.

Double Helix:

Dominant allele: In a diploid cell, an allele whose expression masks the expression of its partner on the homologous chromosome.

Duplications (DNA): Type of chromosome rearrangement in which a gene sequence occurs in excess of its normal amount in a chromosome.

Endoderm: The inner skin of animal embryos, the inner primary tissue layer, or germ layer that gives rise to the inner lining of the gut and organs derived from it.

Endometrium: Inner lining of the uterus,  consisting of connective tissues, glands and blood vessels.

Energy: the capacity to do work by moving matter against an opposing force

Environment:

Enzyme:

Epididymus:  A long coiled duct located on the top of the testicles that is important for sperm maturation and storage site.

Ester Linkage:

Estrogen: A sex hormone required in egg formation, preparing the uterine lining for pregnancy, and maintaining secondary sexual traits; also influences growth and development.

Eukaryotic cell: A cell that has a true nucleus and many other membrane bound organelles any cell except bacteria.

Evolution: Change within a line of descent over time; entails successive changes in allele frequency in a population as brought about by mutation, natural selection, genetic drift, and gene flow.

Fallopian tubes:  Duct through which eggs travel from the ovary to the uterus.  Also called the oviduct.

Fascia:  a sheet of band of fibrous tissue such as lies deep to the skin or invests muscles and various body organs.

Fatty Acids:

Fertilization: Fusion of sperm nucleus with egg nucleus resulting in a zygote.

Fetus:

Fission:

Follicle: In a mammalian ovary, a primary oocyte (immature oocyte) together with the surrounding cells.

Fossils: Recognizable evidence of an organism that lived in the distant past.  Most fossils are skeletons, shells, leaves, seeds, and tracks that are buried in rock layers before they could be decomposed.

Frequency:

FSH (follicle stimulating hormone): One of the gonadotropic hormones of the anterior pituitary, which stimulates the growth and maturation of graafian follicles in the ovary, and stimulates spermatogenesis in the male.

Fusion:

Gametogenesis: The generation of gametes.

Gametophyte: The haploid, multicellular gamete producing phase in the life cycle of most plants.

Gastrulation: Stage of embryonic development in which cells become arranged into two or three primary tissue layers (germ layers); in humans, the layers are an inner endoderm, an intermediate mesoderm and an surface ectoderm.

Gene Flow:

Genes: Any unit of the units of instruction for heritable traits.  Each gene is a linear sequence of nucleotides that calls for the assembly of a sequence of specific amino acids into a polypeptide chain.

Genetic Drift:

Genetic recombination: Presence of a new combination of alleles in a DNA molecule compared to the parental genotype; the result of processes such as crossing over at meiosis, chromosome rearrangements, gene mutation and recombinant DNA technology.

Genotype: Genetic constitution of an individual.  Can mean a single gene pair or the sum total of the individual genes. Compare phenotype.

Germ Cells: Animal cell that may give rise to gametes.  Compare somatic cells.

Germination:

Glycogen:

Glycosidic:

Gonads: Primary reproductive organ in which gametes are produced.

Guanine:

HCG (human chorionic gonadotropin): The hormone released by the embryo once implanted in the uterus that insures the continued release of progesterone by the corpus luteum.  This is the hormone that is detected by pregnancy tests.

Heredity: The transmission of characters from parent to offspring.

Heterogeneous:

Heterozygous: For a given trait having nonidentical alleles at a particular locus on homologous chromosomes.

Homeobox:  A series of regulatory genes that control what genes are 'turned on' in their region of the growing embryo.  The homeobox genes are arranged on the chromosomes in the same sequence as they are used in the body; homeobox gene 1 is responsible for the top of the head, #2 is for eye level, etc. These are present in humans, mice, fruit flies, and even as far back as flat worms.

Homologous Chromosomes: One of a pair of chromosomes that resemble each other in length, shape, and the genes they carry, and that pair with each other at meiosis.  X and Y chromosomes differ in these respects but still function as homologues

Homologous Structures:  Similarity in some aspect of body form or patterning between different species; evolutionary outcome of descent from a common ancestor.

Homozygous: For a given trait, having two identical alleles at a particular locus on homologous chromosomes

Hydrogen Bonds:

Hydrolysis:

Hydrophilic:

Hydrophobic:

Hydroxyl:

Hypothalamus: Of vertebrate forebrains a brain center that monitors visceral activities (such as salt-water balance, temperature control, and reproduction) and that influences related forms of behavior (as in hunger, thirst, and sex.)

Interphase: Of cell cycles, the time interval between nuclear divisions in which a cell increases its mass, roughly doubles the number of its structures and organelles, and replicates its DNA.  The interval is different for different species.

Inversions (DNA): Type of chromosome rearrangement in which a segment that has become separated from the chromosome is reinserted at the same place but in reverse, so the position and sequence of genes are altered.

Ionic Bonds:

Ions:

Ketone:
 
Kinetic energy: the energy of motion, does work by transferring motion from one body of matter to another.

Lineages:

Linkage: Tendency of genes located on the same chromosome to stay together during meiosis and to end up together in the same gamete.

Locus:

Macromolecules:

Mammary Glands:

Meiosis: Two stage nuclear division process in which the parental number of chromosomes in each daughter nucleus becomes haploid.

Menstrual Cycle: The cyclic release of oocytes and priming of the endometrium to receive a fertilized egg; the complete cycle averages 28 days in female humans.

Mesoderm: In most animal embryos, a primary tissue layer between ectoderm and endoderm; gives rise to muscle, organs of circulation, reproduction, and excretion, most of the internal skeleton, and connective tissue layers of the gut and body covering.

Metabolism:  the sum of all the chemical reactions occurring in the cells of an organism.  Metabolism is complex, efficient, well integrated and responsive to subtle changes in conditions.

Metamorphosis: Transformation of a larva into an adult form by way of major tissue reorganization.

Metaphase: Stage of mitosis when spindle has fully formed, sister chromatids of each chromosome become attached to opposite spindle poles, and all chromosomes lie at the spindle equator.

Microtubule: Hollow cylinder of mainly tubulin subunits; a cytoskeletal with roles in cell shape, motion, and growth and in the structure of cilia and flagella.

Mitosis Type of nuclear division that maintains the parental number of chromosomes for daughter cells.  It is the basis of bodily growth and, in some cases, of asexual reproduction of eukaryotes.

Monohybrid: An experimental cross between two parent organisms that breed true for distinctly different forms of a single trait; heterozygous offspring results.

Monomer:

Monosaccharides:

Morphology:

Morphogenesis: Processes by which differentiated cells in a embryo become organized into tissues and organs, under genetic controls and environmental influences.

Mutation: A heritable change in the molecular structure of DNA.

Nitrogen Base:

Nondisjunction: Failure of one or more chromosomes to separate during meiosis.

Nuclear Envelope: A double membrane that is the outermost portion of a cell nucleus.

Nucleotide:

Nucleus: A membranous organelle containing the DNA in an eukaryotic cell.

Organic:

Organogenesis: Formation of a female gamete, from a germ cell to a mature haploid ovum.

Ovary: In female animals, the primary reproductive organ in which eggs form.  In seed bearing plants, the portion of the carpal where eggs develop, fertilization takes place, and seeds mature.  A mature ovary and sometimes other plant parts is a fruit.

Oviduct: Duct through which eggs travel from the ovary to the uterus.  Formerly called the fallopian tubes.

Ovulation: During each turn of the menstrual cycle, the release of a secondary oocyte from the ovary.

Ovule: Any of one or more structures that form on the inner wall of the ovary of seed bearing plants and that, at maturity, are seeds.  An ovule contains the female gametophyte with its egg, surrounded by nutritive and protective tissues.

Oxytocin: A hormone made in the hypothalamus and released from the posterior pituitary that stimulates muscle contraction in the mammary glands and the uterus.

Penis: A male organ which deposits sperm into the female reproductive tract.

Peptide Bond:

Petals:

Phenotype: Observable trait or traits of an individual, arises from interactions between genes, and between genes and the environment

Phosphate Group:

Phosphodiester:

Phospholipids:

Pituitary Gland: Of vertebrate endocrine systems, a gland that interacts with the hypothalamus to coordinate and control many physiological functions, including the activity of many other endocrine glans.  Its posterior lobe store and secretes hypothalamic hormones, the anterior lobe produces and secretes its own hormones

Placenta: A specialized organ that develops in certain mammals, connecting mother to unborn offspring

Placental Barrier: The inability of many substances to cross from the maternal to the fetal system.

Polar:

Polar Bodies: Small cells generated during during gamete meiosis, enabling much cytoplasm to be partitioned into just one of the four meiotic products, the ovum.

Pollen:

Pollination:

Polymer:

Polypeptide:

Polysaccharide:

Population: Any group of interbreeding organisms

Potential energy: stored energy that results for the specific location or arrangement of matter

Primates: An individual belonging to the highest order of mammals, Primates which includes man and the apes, monkeys, and lemurs.

Principle of Independent Assortment: 

Principle of Segregation: Diploid organisms inherit a pair of genes for each trait (on homologous chromosomes)

Products:

Progesterone: A hormone produced by the ovaries that controls secretion patterns of other hormones involved in reproduction.

Prokaryotes: A structurally simple cell, lacking organelles.

Prophase: The first stage of cell division, when chromosomes condense and become visible.  During prophase of meiosis 1, synapses and crossing over occur.

Prostate: A male gland that produces a milky white, alkaline fluid that activates sperm.

Protein:

Puberty: The stage in a humans life when acne occurs, sexual reproductive organs become active.

Purines:

Pyrimidines:

Recessive: An allele whose expression is masked by the activity of another allele

Reductive division: Meiosis 1, when the diploid chromosome number is halved

Replication: The process of duplicating or reproducing, as replication of an exact copy of a polynucleotide strand of DNA or RNA.

Ribose:

RNA: Ribonucleic acid a category of nucleotides used in translating the genetic message of DNA into protein.

Saturated:

Scrotum: The pouch that contains the testes and their accessory organs.  It is composed of skin, the dartos, fascia, and the tunica vaginalis. 

Seminiferous Tubules:

Sepals:

Sexual Reproduction:

Solubility:

Somatic Cells:

Sperm:  Mature male gamete.

Speciation:

Species:

Specialization:

Spindle Fibers: Microtubules that form during mitosis or meiosis and that move the chromosomes

Spore: Of fungi, a walled, resistant cell or multicellular structure, produced by mitosis or meiosis, that can germinate and give rise to a new mycelium.  Of land plants, a reproductive cell formed by meiosis that can develop into gametophyte

Sporophyte: Diploid, spore-producing stage of plant life cycles.

Stabilizing Selection:

Stamens:

Starch:

Steroids:

Stigma:

Substrates:

Synapses: Moment by moment combining of excitatory and inhibitory signals arriving at a trigger zone of a neuron

Template:

Testicles (testes): Male gonad, primary reproductive organ in which male gametes and sex hormones are produced

Testosterone: In male mammals, a major sex hormone that helps control male reproductive functions

Tetrad:

Thermodynamics, first law of: conservation of energy, states that energy cannot be created or destroyed. Thus, the total amount of energy in the universe is constant.

Thermodynamics, second law of: every time energy changes form, there is an increase in entropy (S), a measure of disorder, or randomness. Some energy is dissipated as heat, random molecular motion.  Whenever matter becomes more ordered it does so at the expense of contributing to the disorder of the surroundings.

Thymine:

Transcription: of protein synthesis, the assembly of an  RNA strand on one of the two strands of a DNA double helix; the base sequence of the resulting transcript is complementary to the DNA region on which it is assembled

Translation: Of protein synthesis, the conversion of the coded sequence of information in mRNA into a particular sequence of amino acids to form a polypeptide chain; depends on interactions of rRNA, tRNA, and mRNA

Translocations (DNA): Of cells, the transfer of part of one chromosome to a nonhomologous chromosome.  Of vascular plants, the conduction of organic compounds through the plant body by the way of the phloem

Trait: A characteristic found in your genes

Triglycerides:

Tubulin:

Tunica Vaginalis:  The thin and watery membrane covering the front and sides of testis and epididymus.

Unsaturated:

Uracil:

Urethra: The small opening through which secretions pass in the penis

Uterus: Chamber in which the developing embryo is contained and nurtured during pregnancy

Vas Deferens: 

Vestigial Structures:  A structure that seems not to have a function in an organism but resembles a functional organ in another type of organism.