Topic 8: Classical Genetics Flashcards
Genotype is…
All of an organisms genes/alleles
Phenotype is…
the physical manifestation of the genotype (observable)
Traits controlled by the action of a single genetic locus are… e.g.
Discrete traits or mendelian traits
e.g. wet vs dry earwax, hairy ears
Traits that require the influence of multiple genes to results in the phenotype are… e.g.
Quantitative or continuous traits
e.g. height, weight
Homozygous vs heterozygous vs hemizygous
Homo = cell/organism with identical alleles of a gene of interest
Hetero = cell/organism with different alleles of a gene of interest
Hemi = cell/organism that naturally only has one copy of a gene normally residing on a sex chromosome
Gene vs allele
Gene = a region of a chromosome that is transcribed and influences phenotype
Alleles = a variant of a gene
Dominant allele is…
Fully expressed when only one copy is present
If the mutant allele is recessive…
Wildtype allele is haplosufficient (dominant)
If mutant allele is dominant…
WT allele is haploinsufficient
R vs r alleles in Mendel’s peas
R = WT allele, dominant, R phenotype = round pea
r = mutant allele, r phenotype = wrinkled
Why would a pea be wrinkled
Does not properly fill with starch
Gregor Mendel studied…
inheritance of many different phenotypes in pea plants
What kind of traits did Mendel study
discrete traits (straighforward geno-pheno relationship) that showed complete dominance
Basic principles of heredity
- Existence of genes
- Genes are in pairs i.e. diploid
- 1st law
- 3rd law
- 2nd law
1st, 2nd, and 3rd laws of heredity
1 = segregation (alleles separate in gametes in equal proportions)
2 = independent assortment (dihybrid crosses only)
3 = dominance
