Pre-Midterm Flashcards
P0
Parental cross
‘True breeding’
Homozygotes
Assumed blending inheritance
Average of parental phenotypes.
Gene
Generally, a specific region of the genome that codes for a particular protien.
Allele
A specific sequence of a gene, generally to compare between alleles of a single gene.
Homozygote
In diploids, where both copies of a gene are the same allele- a genotype.
Heterozygote
In diploids, where both copies of a gene are different alleles-a genotype.
Dominant
Allele’s phenotype appears in both homozygotes and heterozygotes.
Recessive
Allele’s phenotype only evident in homozygotes.
Genotype
The genetic sequence of interest.
Phenotype
The physical/cellular/protein results of a genotype and environmental effects. Characteristics produced by different genotypes, also a response to the environment.
Dominant
Allele’s phenotype appears in both homozygotes and heterozygotes.
Feature of the phenotype.
Recessive
Allele’s phenotype only evident in homozygotes.
Feature of the phenotype.
F1
First generation offspring/hybrid (heterozygotes)
Shows dominant phenotype.
Genotypes hidden.
F2
Second generation offspring/hybrids
Not all heterozygotes
Shows all possible phenotypes
Can infer all genotypes.
Monohybrid cross
Looking at a single trait/gene.
Dihybrid cross
Looking at 2 traits/genes.
Test cross
Determining unknown genotype by crossing an unknown individual with a homozygous recessive.
Mendel’s Approach I
Designed crosses carefully and kept detailed records of each.
Kept track of generations.
Mendel’s Approach II
Mendel created true breeding lineages.
Plants were crossed repeatedly until all offspring looked like parentals–>homozygotes.
Mostly done through selfing.
Mendel’s Conclusions II
Alternative versions of genes account for variation in inherited characteristics.
Diploid organisms inherit two alleles, one from each parent.
If two alleles are different one may be dominant.
Each haploid gamete carries only one allele of a given trait because they segregate from one another during meiosis.
Law of Segregation
The first mendelian law.
Alleles of a gene separate independently (randomly) from each other during transmission from parent offspring.
The dominant phenotype appears at 100% in the F1.
The phenotypic frequencies in F2 conforms to 3:1 (dominant:recessive)
Mendel’s Explanation
=Genotype
How can you determine the genotype of an unknown
Test cross
The frequency of the hybrid recessive allele
=Frequency of the recessive phenotype
