Allele

discrete unit, variation of a gene.

o   Principle of independent assortment

This one is wrong.

Each allele is independent.

o   Principle of segregation

 CORRECT

1 allele from paternal and 1 allele from maternal side.

o   Dominant

§  Expressed as heterozygous and homozygous

o   Recessive

§  Expressed homozygous

o   Modern Synthesis

§  1920’s, 20 years after Mendel’s work

§  Stage 1

·         Production and distribution of variation (alleles)

§  Stage 2

·         Selection process of alleles

·         defined as a change in ALLELE frequency over time.

§  >>>>> Individual is selected, population evolves.

§  Reproductive success is still evolutionary success.

o   Production and Distribution

§  New allele is the product of mutation

·         Random, beneficial, harmful, neutral. ---evolution

·         Point mutation or greater

§  Reproduction speed relates to mutation frequency

·         Mutation that affects evolution must occur in sex cells.

·         MUTATION IS THE ONLY WAY TO GET NEW ALLELES

o   Hardy-Weinberg Equilibrium Theory

§  Mating is random. B/C you don’t know the person’s genotype

§  BUT WE select the phenotype.

§  YOU, DON’T GET RID OF RECESSIVE ALLELS EASILY!

§  Gene flow

·         Exchanging genes between populations

·         Different allele combinations.

o   Hybrid vigor

§  Superior qualities in the following generations.

§  Arising from the cross breeding of different individuals.

o   GENETIC DRIFT

§  Alleles randomly removed from gene pool

FOUNDER EFFECT

·         PART OF POPULATION BREAKS OFF OF LARGER POPULATION AND FORMS THEIR OWN POPULATION.

BOTTLENECK EFFECT

·         CATASTROPHE THAT KILLS 50%+ OF POPULATION

o   Volcanic

o   Hurricane

o   Etc

o   = reduction of their allele.

SELECTION

§  acts on Phenotype (explains the retention of harmful recessive alleles.)