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Unformatted text preview: e specific allelic composition of a cell or set of genes.
Haploid: A cell or organism having only one set of chromosomes (i.e., one gene at each locus or haploid).
Gamete: A haploid reproductive cell such as a sperm (or pollen) and egg (or ova).
Heterozygous: A diploid with dissimilar alleles at one or more loci and therefore not true-breeding for the trait(s)at that
locus or loci.
Homozygous: A diploid having the same allele at a given locus, therefore, true-breeding for the trait at that locus.
Locus: The region along the length of a chromosome where the alleles (pair of genes) for a particular trait resides.
Monohybrid Cross: A cross between two individuals with different alleles at one gene locus. A monohybrid is a
heterozygous individual with different alleles at one gene locus.
N: The haploid chromosome number. Prokaryotes are 1N while most eukaryotes are 2N.
Phenotype: The detectable outward biochemical or morphological manifestation of a specific genotype. The form a
character or trait takes in a specific individual.
Punnett Square: A cross-multiplication table used for determining the expected genetic outcomes of a mating.
Recessive: An allele or trait that does not express its phenotype in the heterozygous condition (e.g., a is recessive to A
when the phenotype of Aa is the same as AA).
Testcross: A cross between an F1 individual (unknown genotype) and the homozygous recessive parent of the F1, the
"tester." Because the genotype of the tester is known, the test cross reveals the genotype of the F1.
BIS101001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013 BIS101001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez 4 Genetics Vocabulary: This lecture
Bivalents: Homologous pairs of chromosomes seen in the pachytene stage of prophase I of meiosis.
Chiasmata: The visible crossover structures commonly observed between nonsister chromatids during
the diplotene stage of meiosis.
Centromeres: A specialized region of the chromosome (usually constricted) where spindle fibers attach
during mitosis and meiosis.
Chromatids: Two daughter strands of the same duplicated chromosome joined together at the
centromeres. Upon division of the centromeree in Anaphase II, the sister chromatids separate.
Haplosufficient:In heterozygotes, if the single wild type allele is sufficient to produce the wild type
phenotype (haplosufficient), then the mutation is recessive. If the single wild type allele is not sufficient
for the wild type phenotype (haplo-insufficient), then the loss-of-function mutation is dominant
Hemizygous: A single dose of a gene. One allele of the gene is missing either because it has been
deleted from one member of the chromosome pair or because it is located on the X chromosome of a XY
Kinetichore: A complex of DNA and protein at the centromeree to which spindle fibers attach.
Meiocyte: A cell that is destined to become a gamete (sperm...
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This note was uploaded on 02/12/2014 for the course BIS 101 taught by Professor Simonchan during the Spring '08 term at UC Davis.
- Spring '08