Term
| Chromosome theory of inheritance |
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Definition
| In this theory, genes have specific loci along chromosomes, and it is the chromosomes that undergo segregation and independent assortment |
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| The phenotype for a character most commonly observed in natural populations. |
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| Traits that are alternatives to the wild type.... they are due to alleles assumed to have originated as changes, or mutations, in the wild type of allele |
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| A gene located on either sex chromosome...(those on the Y, are called Y linked genes. Y chromosomes are passed on virtually intact from father to son...very few disorders are passed from father to son)(those linked to the X, are X linked genes) |
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Definition
| Refers to X linked genes in males...Homozygous and heterozygous do not apply since males only have one locus... Any male receiving the recessive allele from his mother will express the trait. (duchenne muscular dystrophy is an example of a X linked gene disorder) |
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Definition
| Since females receive two X chromosome while males only have one, one of the X chromosomes becomes inactivated and condenses into a compact object (Barr body) which lies along the inside of the nuclear envelope... In the ovaries, Barr body chromosomes are reactivated, so every female gamete has an active X chromosome. |
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| Reference Barr body card... One of the X chromosomes become condensed... However, the X chromsome that becomes condense is independent of which X chromosomes becomes condensed in another cell in the embryonic cell present at the time of X inactivation (cells that are produced by mitosis will have the same chromosome condensed)... So as a result females are a mosaic of cells that have X activated chromosomes from their father and X activated chromosomes from their mother... Inactivation involves modification of DNA, and the histone proteins bound to it...XIST (X-inactive specific transcript) becomes active only on the chromosome that will become a barr body |
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| Genes located near each other on the same chromosome tend to be inherited together in genetic crosses |
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| The production of offspring with combinations of traits that differ from those found in either parent. |
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| Offspring are expected to inherit a phenotype that matches either of the parental (P generation) phenotypes. |
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| Recombinant types (recombinants) |
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Definition
| Offspring have new combinations of traits from P generation...differ in appearance from parents |
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Definition
| an ordered list of the genetic loci along a particular chromosome |
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| A genetic map based on recombination frequencies |
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| One map unit is equivalent to a 1% recombination frequency... a way to express distance between genes |
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| Locates genes with respect to chromosomal features, such as stained bands. |
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| Occasional mishaps of meiosis, in which members of a pair of homologous chromosomes do not move apart properly during meiosis I or sister chromatids fail to separate during meiosis II... One gamete would receive two of the same type of chromosome while another gamete receives no copy. |
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Definition
| A gamete is an abnormal amount of chromosomes unites with a normal gamete will produce a zygote with an abnormal amount of chromosomes |
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Definition
| Fertilization involving a gamete that has no copy of a particular chromosome will lead to a missing chromosome in the zygote (2n-1)... the aneuploid zygote is said to be monosomic |
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Definition
| If a chromosome is present as a triplicate in the zygote (2n+1 chromosomes), the aneuploid zygote is said to be trisomic |
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| Organisms that have more than two complete chromosome sets in all somatic cells.... common in the plant kingdom |
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| occurs when a chromosomal fragment is lost |
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| The "deleted" fragment may become attached as an extra segment to a sister chromatid |
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| When a chromosomal fragment reattaches to the original chromosome but in the reverse order. |
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Definition
| When a fragment joins a non homologous chromosome |
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Definition
| Variation in phenotype depending on whether an allele is inherited from the male or female parent. (most imprinted genes are on autosomes) |
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