13.6 Genetics Flashcards
Gene definition
A section of DNA that codes fore a specific protein
Genotype definition
The genetic constitution of an organism, all the alleles that an organism posseses
Gene pool
All the alleles with an interbreeding population at a specific time
Population definition
All the individuals of the same species that occupy the same area at the same time
Phenotype definition
The organisms phenotype is the expression of its genetic constitution and its interaction with the environment
Allele definition
Different version of the same gene
Multiple alleles definition
More than 2 alleles for the same gene, this produces a heirarchy of dominance
Locus definition
Different alleles for the same gene are found at the same position on the homologous chromosome, this position is the locus of the gene
Homozygous definition
Most organisms are diploid, they have two copies of each chromosome
If the two copies of the gene are the same allele, the organism is homozygous
Heterozygous definition
If the two copies of the gene have different alleles
Dominant allele definition
If the allele is dominant it will always be expressed in the phenotype
Recessive allele definition
It will only be expressed in the phenotype if the genotype is homozygous
Codominant alleles definition
Equally expressed within the phenotype
Diploid definition
Adult cells are normally diploid, two copies of a gene
Haploid definition
Gametes are haploid, one copy of a gene
Ratio of monohybrid
3:1
Ratio of codominance
1:2:1
Ratio of dihybrid
9:3:3:1
Ratio of epistasis
9:4:3
15:1
9:7
Ratio always adds up to 16
Ratio of autosomal linkage
3:1
Hardy - Weinberg equations
p+q=1
p^2 + 2pq + q^2= 1
What is p^2?
Homozygous dominant individuals
What is 2pq?
Heterozygous individuals
What is q^2?
Homozygous recessive individuals
What is p?
Dominant alleles
What is q?
Recessive alleles
What does hardy-weinbergs principal predict?
The allelic frequency from one generation to the next will remain constant if there is no:
- migration
- gene mutations
- selection
should be:
- a large population
- mating should be random
Dominant characteristic rules
- affected offspring must have at least one affected parent
- unaffected offspring only have unaffected parents
- if both parents are affected and have unaffected offspring, both parents must be heterozygous
Recessive characteristic rules
- unaffected parents can have unaffected offspring if they are heterozygous
Sex linked rules for dads and daughters
- if a daughter is affected, her father is not, and its a recessive disease
- it is NOT sex linked
Sex linked rules for mothers and sons
- if a son is affected and his mum is not, and it is a dominant disease
- it is NOT sex linked
Linkage group definition
A set of genes on the same chromosome which tend to be inherited together
Epistasis definition
An interaction between two genes where one allele affects the expression of another
