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Unformatted text preview: Biology 1320 Review sheet for Hour Exam 3 Dr. Upchurch Transmission Genetics • Know Mendel’s laws of inheritance: Gene, principles of segregation and random assortment, principle of dominance • Gregor Mendel o Austrian Monk o Principles by which traits are transmitted o Experiments with peas o Work unnoticed until 20 th century o Died in obscurity • Ideas regarding inheritance, 1800s o Principles were not well understood Mixing • Two parents • Equal mixing of traits in offspring • Blending pattern Plant and animal breeding – unseen traits can appear!!! o Mendel – plant breeding Particulate theory of inheritance • Traits are inherited as individual units • These traits separate from each other and recombine randomly • One trait can be masked by another trait Experiments with peas • Peas easier to understand how traits are transmitted • Traits inherited individually • Can appear out of nowhere because of being masked by another trait • Inheritance Terms o Gene Unit of information for a heritable trait, passed from parents to offspring Protein o Ploidy Diploid • Presence of two of each type of chromosome • 2n Haploid • Presence of only half of the parental number of chromosomes in a spore or gamete, as brought about by meiosis • 1n o Homologous chromosomes Of cells with a diploid chromosome number, one of a pair of chromosomes identical in size, shape, and gene sequence, and that interact as homologues during meiosis Equivalent chromosomes come in pairs same linearity o Allele One of two or more molecular forms of a gene that arise by mutation and code for different versions of the same trait Alternate form of a gene o Phenotype Observable trait or traits of an individual that arise from gene interactions and gene- environment interactions Physical manifestation o Genotype Genetic constitution of an individual A single gene pair or the sum total of an individual’s genes Genetic structure o True-breeding of sexually reproducing species, a lineage in which only one version of a trait appears over the generations in all parents and their offspring all kids breed among selves same trait passed on through generations o Homozygous Having a pair of alleles at a gene locus One allele, one variant for trait o Heterozygous Having a pair of nonidentical alleles at a gene locus Two alleles, two forms of trait o Dominant An allele that mask the phenotypic effect of any recessive allele paired with it Always shows up o Recessive Allele whose expression in heterozygotes is fully or partially masked by expression of its partner Fully expressed in homozygous recessives Can be hidden by dominant trait • Principles of Inheritance o Segregation Sexually reproducing organisms inherit pairs of genes, the two gens of each pair are separated from each other at meiosis, and they end up in separate gametes Come apart from each other...
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This note was uploaded on 04/18/2008 for the course BIO 1320 taught by Professor Farr during the Fall '08 term at Texas State.
- Fall '08