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23 Cards in this Set
- Front
- Back
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Locus |
Location on chromosome where gene is located |
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Allele |
variance of genes such as different color |
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Gene |
Genetic material on a chromosome for a trait |
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Homologous chromosomes |
a pair of chromosomes that contains same genetic material. Each parent contributed 1 of the chromosome in the pair and this different alleles may exist for a gene |
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Law of segregation |
One member of each chromosome pair migrates to an opposite pole so that each gamete is haploid, occurs in anaphase I |
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Law of Independent assortment |
migration of homologues within one pair of homogous chromosomes does not influence the migration of homelogoue of other homologous pairs |
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Test crosses |
Monhybrid crosses test one gene Dihybrid test two (on different chromosomes)
Unknown dominant genotype X homozygous recessive phenotype to determine if hetero or homo dominant. |
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Incomplete Dominance |
Blending of expressions of alleles (red and white become pink) |
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Codominance |
oth inherited alleles are completely expressed (blood types A and B or both can show up as AB if expressed) |
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Epistasis |
One gene affects phenotypic expression of 2nd gene Pigmentation(one gene controls (turn on/off) the production of pigment and 2nd gene control color or amount) If 1st gene codes for no pigment --> 2nd gene has no effect |
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Pleiotropy |
single gene has more than 1 phenotypic expression (gene in pea plants that expressed seed texture also influences phenotype of starch metabolism and water uptake; SICKLE CELL ANEMIA LEADS TO DIFFERENT HEALTH CONDITION) |
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Polygenic inheritance |
the interaction of many genes to shape a single phenotype w/ continuous variation (height, skin color) |
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Linked genes |
two or more genes that reside on the same chromosomes and this cannot separate independently because they are physically connected (inherited together) Linked genes exhibit recombination about 18% of the time - Greater recombination frequencies (18% above) means farther distance of genes apart on the same chromosome B-V is 18%, A-V is 12% and B-A is 6% --> B----A--------V |
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Sex-linked |
refers to single gene resides on sex chromosome when male (XY) receives an X from mother, whether it is dominant or recessive will be expressed because there is no copy on the Y chromosome |
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Sex-influenced |
can be influenced by sex of individual carrying trait Bb female not bald, Bb male is
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X-inactivation |
during embryonic development in female mammals, one of two X chromosomes does not uncoil into chromatin --> dark and coiled compact body chromosome (barr body) --> cannot be expressed. Thus, only the genes on the other X chromosome will be expressed. Either one can be inactivated --> genes in the female will not be expressed, so all cells in a female mammal not necessarily functionally identical
Ex: Hemophilia |
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Nondisjunction |
failure of one/more chromosomes pairs or chromatids to separate during mitosis or meiosis Fraction of body cells have extra or missing chromosome |
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Polyploidy |
All chromosomes undergo meiotic nondisjunction and produce gametes with twice the number of chromosomes Common in plants |
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Point mutation |
single nucleotide changes causing substitution, insertion, deletion - transition mutation: purine to purine or pyrimidine to pyrimidine
Transversion mutation: purine to pyrimidine or vice versa |
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Aneuploidy |
genome with extra/missing chromosome; often caused by nondisjunction (down syndrome =trisomy 21) Turner syndrome: nondisjunction in sex-chromosome.
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Duplications |
chromosome segment is repeated on same chromosome |
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Inversion |
chromosome segments are rearranged in reverse orientation |
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Translocation |
segment is moved to another chromosome (21 on 14 can cause Down's as well, tripled 21 chunck) |
