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Bio Chapter 6
Term | Definition |
---|---|
Somatic Cell | Cell that makes up all of the body tissues and organs, except gametes |
Gamete | A haploid reproductive cell that unites with another haploid reproductive cell to form a zygote |
Homologous chromosome | Chromosomes that have the same length, appearance, and copies of genes, although the alleles may differ |
Autosome | Any chromosome that is not a sex chromosome |
Sex Chromosome | One of the pair of chromosomes that determine the sex of an individual |
Sexual reproduction | Reproduction in which gametes from two parents unite |
Fertilization | The union of a male and female gamete to form a zygote |
Diploid | A cell that contains two haploid sets of chromosomes |
Haploid | Describes a cell, nucleus, or organism that has only one set of unpaired chromosomes |
Meiosis | A process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells (gametes or spores) |
Gametogenesis | Process by which gametes are produced through the combination of meiosis and other maturational changes |
Sperm | Male gamete |
egg | Female gamete |
Polar Body | One of the small cells that separate from an oocyte during meiosis, that have little cytoplasm, and that are ultimately discarded |
Trait | One of two or more possible forms of a character; a recognizable feature or characteristic of an organism |
Genetics | The science of heredity and of the mechanisms by which traits are passed from parents to offspring |
Purebred | Type of organism whose ancestors are genetically uniform |
Cross | Mating of two organisms |
Law of segregation | Mendel's first law, stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only one copy of each gene in their gametes because the genes separate during gamete formation |
Gene | The most basic physical unit of heredity; a segment of nucleic acids that codes for a functional unit of RNA and/or a protein |
Allele | One of the alternative forms of a gene that governs a characteristic, such as hair color |
Homozygous | Describes an individual that has identical alleles for a trait on both homologous chromosomes |
Heterozygous | Describes an individual that carries two different alleles of a gene |
Genome | The complete genetic material contained in an individual or species |
Genotype | The entire genetic makeup of an organism; also the combination of genes for one or more specific traits |
Phenotype | An organism's appearance or other detectable characteristic that results from the organism's genotype and the environment |
Dominant | In genetics, describes an allele that is fully expressed whenever the allele is present in an individual |
Recessive | In genetics, describes an allele that is expressed only when no dominant allele is present in an individual |
Punnett Square | A graphic used to predict the results of a genetic cross |
Monohybrid cross | A cross between individuals that involves one pair of contrasting traits |
Testcross | Cross between an organism with an unknown genotype and an organism with a recessive phenotype |
Dihybrid Cross | A cross between individuals that have different alleles for the same gene |
Law of independent Assortment | The law that states that genes separate independently of one another in meiosis |
Probability | The likelihood that a possible future event will occur in any given instance of the event; the mathematical ratio of the number of times one outcome of any event is likely to occur to the number of possible outcomes of the event |
Crossing over | Exchange of chromosome segments between homologous chromosomes during meiosis I |
Genetic linkage | Tendency for genes located close together on the same chromosomes to be inherited together |