genetics terms and definitions 3

genetics terms and definitions 3 - 1. Acentric chromatid:...

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1. Acentric chromatid: lacks a centromere; produced when crossing over takes place within a paracentric inversion. The acentric chromatid does not attach to a spindle fiber and does not segregate in meiosis or mitosis; so it is usually lost after one or more rounds of cell division. 2. Acrocentric chromosome: chromosome in which the centromere is near one end, producing a long arm at one end and a knob, or satellite, at the other end. 3. Additive genetic variance: component of the genetic variance that can be attributed to the additive effect of different genotypes. 4. Adjacent 1 segregation: type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N 1 and N 2 and the chromosomes containing the translocated segments are T 1 and T 2, then the adjacent-1 segregation takes place when N 1 and T 2 move toward one pole and T 1 and N 2 move toward the opposite pole. 5. Adjacent 2 segregation: type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N 1 and N 2 and the chromosomes containing the translocated segments are T 1 and T 2 , then adjacent-2 segregation takes place when N 1 and T 1 move toward one pole and T 2 and N 2 move toward the opposite pole. 6. Allelic frequency: proportion of a particular allele in a population 7. Allopolyploidy: condition in which the sets of chromosomes of a polyploid individual possessing more than two haploid sets are derived from two or more species 8. Alternate segregation: type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N 1 and N 2 and the chromosomes containing the translocated segments are T 1 and T 2 , then the alternate segregation takes place when N 1 and N 2 move towards one pole and T 1 and T 2 move toward the opposite pole. 9. Aneuploidy: change from the wild type in the number of chromosomes; most often an increase or decrease of one or two chromosomes. 10. Artificial selection: selection practiced by humans 11. Ascospore: the sexual spore of Ascomycetes, it is formed within an ascus; typically eight ascopores will be formed in each ascus. 12. Autopolyploidy: condition in which all the sets of chromosomes of a polyploidy individual possessing more than two haploid sets are derived from a single species. 13. Balance hypothesis: proposes that much of the molecular variation seen in natural populations is maintained by balancing selection that favors genetic variation 14. Branch: evolutionary connections between organisms in a phylogenetic tree 15. Broad sense heritability: proportion of the phenotypic variance that can be attributed to genetic variance 16. C value: haploid amount of DNA found in a cell of an organism 17. Centromere mapping: the process of measuring the difference between one or more loci and the centromere. Distances are usually measured in centimorgans 18. Centromeric sequence: DNA sequence found in functional centromeres
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This note was uploaded on 04/30/2009 for the course ZOL 341 taught by Professor Dworkin during the Spring '08 term at Michigan State University.

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genetics terms and definitions 3 - 1. Acentric chromatid:...

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