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| the genetic material of an organism or virus; the complete complement of an organism's or virus's genes along with its noncoding nucleic acid sequences |
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| a cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins. (A bacterial chromosome usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which is not membrane bounded) |
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| the complex of DNA and proteins that makes of eukaryotic chromosomes. When the cell is not dividing, chromatin exists in it dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope |
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| any cell in a multicellular organism except a sperm or egg or their precursors |
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| a haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote |
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| two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II |
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| in duplicated chromosome, the region on each sister chromatid where they are most closely attached to each other by proteins that bind to specific DNA sequences; this close attachment causes a constriction in the condensed chromosome. (an uncondensed, unduplicated chromosome has a single centromere, identified by its DNA sequence |
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| a process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei |
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| the division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II |
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| the phase of the cell cycle that includes mitosis and cytokinesis |
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| the period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase often accounts for about 90% of the cell cycle |
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| the first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins |
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| the synthesis phase of the cell cycle; the portion of interphase curing which DNA is replicated |
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| the second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs |
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| the first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains intact |
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| the second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes |
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| the third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate |
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| the fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell |
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| the fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun |
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| an assemblage of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis |
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| a structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. a centrosome has two centrioles |
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| a radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis |
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| a structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle |
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| an imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located |
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| 1 the process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. 2 the succession of rapid cell divisions without significant growth during early embryonic development that converts the zygote to a ball of cells |
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| the first sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate. |
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| a membrane-bound, flattened sac located at the midline of a dividing plant cell, inside which the new cell wall forms during cytokinesis |
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| a method of asexual reproduction by "division in half". in prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process |
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| site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides |
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| cell cycle control system |
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| a cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle |
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| a control point in the cell cycle where stop an d go-ahead signals can regulate the cycle |
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| a nondividing state occupied by cells that have left the cell cycle, sometimes reversibly. |
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| a cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle |
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| cyclin-dependent kinases (Cdks) |
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| a protein kinase that is active only when attached to a particular cyclin. |
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| 1 a protein that must be present in teh extracellular environment (culture medium or animal body) for the growth and normal development of certain types of cells. 2 a local regulator that acts on nearby cells to stimulate cell proliferation and differentiation |
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| density-dependent inhibition |
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| the phenomenon observed in normal animal cells that cuases them to stop dividing when they come into contact with one another |
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| the requirement that a cell must be attached to a substratum in order to initiate cell division |
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| 1 the conversion of a normal animal cell to a cancerous cell. 2 a change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of different species, transformation results in horizontal gene transfer |
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| a mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor's origin |
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| a cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading and surviving in new sites. Malignant tumors can impair the functions of one or more organs |
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| the spread of cancer cells to locations distant from their original site |
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| the transmission of traits from one generation to the next |
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| differences between members of the same species |
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| the scientific study of heredity and hereditary variation |
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| a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA |
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| a haploid reproductive cell, such as an egg or sperm, Gametes unite during sexual reproduction to produce a diploid zygote |
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| any cell in a multicellular organism except a sperm or egg or their precursors |
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| a specific place long the length of a chromosome where a given gene is locate |
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| the generation of offspring from a single parent that occurs without the fusion of gametes (by budding, division of a single cell, or division of the entire organism into two or more parts). in most cases, the offspring are genetically identical to the parent |
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| 1 a lineage of genetically identical individuals or cells. 2 in popular usage, an individual that is genetically identical to another individual. 3 as a verb, to make one or more genetic replicas of an individual or cell |
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| a type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from both parents via the gametes |
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| a display of the chromosome pairs of a cell arranged by size and shape |
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| a pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited form the organism's father, the other from the mother. Also called homologs, or a homologous |
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| a chromosome responsible for determining the sex of an individual |
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| a chromosome that is not directly involved in determining sex; not a sex chromosome |
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| a cell containing two sets of chromosomes (2n) one set inherited from each parent |
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| a cell containing only one set of chromosomes (n) |
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| the diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg |
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| 1 the union of haploid gametes to produce a diploid zygote. |
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| a modified type of cell division in sexually repoducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell |
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| alternation of generations |
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| the first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half of the number of chromosome sets as the original cell |
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| the second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half of the number of chromosome sets as the original cell |
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| the pairing and physical connection of duplicated homologous chromosomes during prophase 1 of meiosis |
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| the reciprocal exchange of genetic material between nonsister chromatids during prophase 1 of meiosis |
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| the x-shaped, microscopically visible region where crossing over has occurred earlier in prophase 1 between the homologous nonsister chromatids. Chiasmata become visible after synapsis ends, with the two homologs remaining associated due to sister chromatid cohesion |
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| a chromosome created when crossing over combines DNA from two parents into a single chromosome |
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| an observable heritable feature that may vary among individuals |
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| one of two or more detectable variants in a genetic character |
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| referring to organisms that produce offspring of the same variety over many generations of self-pollination |
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| in genetics, the mating, or crossing, of two true breeding varieties |
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| the true breeding parent individuals from which F1 hybrid offspring are derived in studies of inheritance; P stand for "parental" |
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| the first filial, hybrid (heterozygous) offspring arising from a parental cross |
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| the offspring resulting from interbreeding of the hybrid F1 generation |
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| any of alternative versions of a gene that may produce distinguishable |
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| an allele that is fully expressed in the phenotype of a heterozygote |
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| an allele whose phenotypic effect of not observed in a heterozygote |
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| mendel's first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation |
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| a diagram used in the study of inheritance to show the predicted genotypic results of random fertilization in genetic crosses between individuals of known genotype |
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| having two identical alleles for a given gene |
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| having two different alleles for a given gene |
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| the observable physical and physiological traits of an organism, which are determined by its genetic makeup |
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| the genetic makeup, or set of alleles, of an organism |
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| breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring reveals the unknown genotype |
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| an organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. For example, parents of genotypes AA and aa produce a monohybrid of genotype Aa |
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| a cross between two organisms that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant0 |
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| an organism that is heterozygous with respect to two genes of interest. All the offspring form a cross between parents doubly homozygous for different alleles are dihybrids. For example, parents of genotypes AABB and aabb produce a dihybrid of genotype AaBb |
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| a cross between two organisms that are each heterozygous for both of teh characters being followed (or the self-pollination of a plant that is heterozygous for both characters) |
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| law of independent assortment |
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| mendel's second law, stating that eac hpair of alleles segregates, or assorts independently of each other pair during gamete formation; applies when genes for two characters aer located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes |
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| a rule of probability stating that the probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilities |
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| a rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities |
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| the situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable |
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| the situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele |
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| the situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways |
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| a human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and metnal performance usually become manifest a few months after birth, followed by death within a few years |
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| the ability of a single gene to have multiple effects |
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| a type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene |
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| a heritable feature that varies continuously over a range rather than in a either-or fashion |
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| an additive effect of two or more genes on a single phenotypic character |
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| the range of phenotypes produced by a single genotype, du to environmental influences |
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| referring to a phenotyhpic character that is influenced by multiple genes and environmental factors |
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