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| Alternative form of a gene. |
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| A gene that expresses itself even when heterozygous. Also, the trait controlled by that allele. |
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| An allele (or phenotype) that does not express itself in the heterozygous condition. |
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Offspring of parents that differ in only one genetic characteristic. Usually implies heterozygosity at a single locus under study.
ex. Bb x Bb |
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An organism that is heterozygous at two different loci.
ex. RrYy
A cross involving two pairs of contrasting characters. |
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| The cross of an organism with a homozygous recessive organism. |
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| The genes an organism possesses. |
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A diploid or polyploid with identical alleles at a locus.
ex. AA |
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A diploid or polyploid with different alleles at a particular locus.
ex. Aa |
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| The observable traits of an organism. |
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| A germ cell having a haploid chromosomal complement. Gametes from parents of opposite sexes fuse to form zygotes. They carry half the genetic information of an organism and are formed by meiosis. |
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| An organism having two copies of each chromosome per nucleus or cell. |
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| The state of having one copy of each chromosome per nucleus or cell. |
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| The chromosome complement of a cell. AKA- What chromosomes you got. Often displayed as a map/graph/pretty pictures! |
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| Constrictions in eukaryotic chromosomes on which the kinetochore lies. Also, the DNA sequence within the constriction that is responsible for binding the kinetochore. AKA- Where the X of the chromosome shape comes together. |
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| The DNA-protein structure that corresponds to one double-stranded DNA molecule. At anaphase of meiosis II or mitosis, when the sister chromatids separate, each chromatid becomes a chromosome. |
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| When the centromere is located in the center of the chromosome. |
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| When the centromere is located between the center and the end of the chromosome. |
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| When the centromere is located at the very end of the chromosome. |
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| The ends of linear eukaryotic chromosomes. |
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| A complex of proteins that are associated with the centromere and attaches to the spindle fibers. |
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| Spindle fibers/Kinetochore microtubules |
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Definition
| Microtubules radiating from the centrosome and attached to kintochores of chromosomes during mitosis and meiosis. |
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| The spindle-microtubule organizing center in eukaryotes that uses spindle pole organizing bodies to organize the spindles. (this definition is straight from the book). |
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| One member of a chromosome pair |
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Structures, formed during prophase of meiosis I, consisting of the synapsed homologous chromosomes.
A bivalent is a pair of associated homologous chromosomes formed after replication. Each replicated chromosome comprises two chromatids. |
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| Cohesin is the protein complex responsible for binding the sister chromatids during synthesis through the G2 phase and into mitosis phase. When two sister chromatids are bound along their lengths by cohesin, the attachment is referred to as sister chromatid cohesion. |
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| The first meiotic division that reduces the number of chromosomes and centromeres to half relative to the original cell. |
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| A chiasma (plural: chiasmata), in genetics, is thought to be the point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis. |
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Definition
Associations of loci on the same chromosome.
A pair or set of genes on a chromosome that tend to be transmitted together. |
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| The separation of the homologs in meiosis I. |
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| Nondisjunction is the failure of chromosome pairs to separate properly during cell division. This could arise from a failure of homologous chromosomes to separate in meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. The result of this error is a cell with an imbalance of chromosomes. |
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