Genetics • Chapter 5 Flashcards
Summary of Chapter 5, according to Nelson Biology WA ATAR Units 3 & 4 -- todo: modes of inheritance (17 cards)
Define
Locus
A location within a gene.
Define
Allele
Variants of a gene.
(e.g. tall [b], and short [B])
Genotype
Combination of alleles that propogate a particular phenotype
(e.g. Bb — short [B] dominates over tall[b].)
Define
Phenotype
Features of an organism as a result of its genotype.
(e.g. tall)
Define
Dominant Allele
An allele that will be expressed in the phenotype if present in the genotype.
(e.g. B will be expressed with genotype Bb and BB.)
Define
Recessive Allele
An allele that will only be expressed in the phenotype if the genotype is homologous.
(e.g. b will only be expressed with genotype bb.)
List
Trait Inheritance Modes
- Autosomal
- Sex-linked
Define
Autosomal
A trait inherited from an autosome.
(chromosome pair 1-22 in humans.)
Sex-linked
A trait inherited on a sex chromosome.
(chromosome pair 23 in humans.)
List
Types of Variation
- Continuous
- Discontinuous
Define
Continuous Variation
Variation in a phenotypic characteristic that shows a spectrum (a smooth range).
(e.g. human height)
Define
Discontinuous Variation
Variation in a phenotypic characteristic that has fixed attributes
(e.g. human blood type)
Define
Polygenic Inheritance
Inheritance where more than one gene contributes to a single phenotypic property.
Define
Polygenes
Genes in polygenic traits that partially contribute to the final phenotypic effect.
Define
Partial/Incomplete Dominance
(ID)
Two different alleles are present, and both partially affect the phenotype
(e.g. pink snapdragon plants [CᴿCᵂ] are an incompletely dominant phenotype of white [Cᵂ] and red [Cᴿ] alleles.)
Define
Codominance
Two unique alleles are both dominant, and both are fully observed in the phenotype.
(e.g. human blood group AB [IᴬIᴮ] — both alleles are dominant, and fully expressed.)
Explain
How is ID and Codominance notated?
XʸXᶻ, where:
* X is a relevant designation (in the case of snapdragon plants, this will be C for color)
* y and z are designations for alleles.
