Inherited Change
- Created by: 14klpotts
- Created on: 11-11-20 11:28
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- Inherited change
- study inheritance
- Genotype: all the alleles an organism has
- Phenotype: the observable/biochemical characteristics of an organism
- Dominant: always expressed in the phenotype Recessive: an allele taht can be carried but not expressed unless there are two present for the gene Codominant: 2 or more alleles that all contribute to the phenotype
- Multiple alleles: when a gene has more than two allelic forms
- Monohybrid Inheritance
- F1 generation: all heterozygous from two pure parents, one homozygous dominant and one homozygous recessive
- F2 generation: 3:1 ratio. Produced from 2 F1 parents that are heterozygotes
- In diploid organisms, characterisitcs are determined by alleles that occur in pairs on the same loci of homologous chromosomes
- F1 generation: all heterozygous from two pure parents, one homozygous dominant and one homozygous recessive
- Probability and genetic crosses
- results of genetic crosses are rarely the same as the expected ratios due to statistical errors
- each cross is independent of the one before so is not affected by the outcome of the fusion of other gametes
- The larger the sample, the more likely the actual results are to come near to matching the theoretical, so it is important to use large samples in genetic crosses to obtain representative results
- each cross is independent of the one before so is not affected by the outcome of the fusion of other gametes
- results of genetic crosses are rarely the same as the expected ratios due to statistical errors
- Dihybrid Inheritance
- Two characteristics determined by two different genes located on different chromosomes are inherited together
- Expected ratio of dihydbrid cross with parents heterozygous for both traits: 9:3:3:1.
- Mendel's law of independent assortment: each member of a pair of alleles may combine randomly with either of another pair
- Expected ratio of dihydbrid cross with parents heterozygous for both traits: 9:3:3:1.
- Two characteristics determined by two different genes located on different chromosomes are inherited together
- Codominance and multiple alleles
- Multiple alleles: where there are more than 2 alleles of which only 2 can be present on the loci of homologous chromosomes
- Codominance: both alleles expressed in the phenotype
- both alleles are equally dominant
- Sex-linkage
- Any gene carried on either the X or the Y chromosome are said to be sex linked
- The X chromosome is much longer than the Y so for most of the length of the X there is no homologous portion of the Y
- Sex linked characteristics are controlled by recessive alleles on the non-homologous portion of the X chromosome
- The X chromosome is much longer than the Y so for most of the length of the X there is no homologous portion of the Y
- Pedigree charts: unaffected male = square, unaffected female = circle. Shaded in circle/square; affected person
- Any gene carried on either the X or the Y chromosome are said to be sex linked
- Autosomal linkage
- Chromosomes that aren't sex chromosomes are called autosomes
- autosomal linkage: when two or more genes are carried on the same autosome.
- assuming there is no crossing over, all linked genes remain together during meiosis and are inherited as a group
- autosomal linkage: when two or more genes are carried on the same autosome.
- Chromosomes that aren't sex chromosomes are called autosomes
- Epistasis
- When the allele of one gene affects/masks the expression of another
- study inheritance
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