Cell Division_Genetic Consequences

Cell Division_Genetic Consequences - BioG104: Cell...

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BioG104: Cell Division—Genetic Consequences January 23, 2008 Mitosis: cell division procedure used by unicellular organisms during asexual reproduction and by multicellular organisms needing to produce additional cells for growth and maintenance Meiosis: produces cells that will serve in a sexual role as gametes or nonsexually as spores in the life cycle Chromosomes: consist of DNA molecules located within the nucleus of the cell o Single-chromatid chromosome: single DNA molecule chromosomes o Double-chromatic chromosome: 2 DNA molecule chromosomes; occurs after DNA replication In preparation for cell division, all single-chromatid chromosomes become double-chromatic chromosomes as their DNA is replicated Immediately after replication, chromatids of double- chromatid chromosomes are genetically identical ( sister chromatids ) o Sister chromatids are attached to each other at the centromere Gene: portion of a chromosome that determines the inheritance of a specific genetic trait o Locus: gene’s location Allele: nucleotide sequence present at gene’s locus o Genotype: listing of symbols representing alleles of the genes being considered o Phenotype: description of the outward expression of alleles in terms of structural and functional characteristics Ploidy (n): number of sets of chromosomes that are present in the cell, where each set includes one of each of the different types of chromosomes o Each chromosome type differs in size, shape, centromere position, and the genes included on the chromosome o Haploid: 1n; one allele for each gene o Diploid: 2n; 2 alleles for each gene 2n cells are formed by the process of fertilization (combines 2-1n cells so that both sets of chromosomes come to reside within the same nucleus) Homologous chromosomes: chromosomes of the same type from the 2 chromosome sets
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Look alike Have the same genes Depending on the 2 parental haploid cells, can have different alleles for the genes present Linked genes: genes that are on the same chromosome Unlinked genes: genes on chromosomes that aren’t homologous Life forms with a sexual mode of reproduction show an alteration between
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This note was uploaded on 09/08/2008 for the course BIO G 104 taught by Professor Chen,k.c during the Spring '06 term at Cornell University (Engineering School).

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Cell Division_Genetic Consequences - BioG104: Cell...

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