Lecture 4 Flashcards
Genotype
Genetic constitution of an organism
Phenotype
An observable feature: physiological, anatomical, even biocheical
Genome
Entirety of an organism’s DNA
3 Sources of Genetic Variation
Mutation, independent assortment, recombination
Mutation Definition
Stable change in DNA sequence
Mutation occurs at a x rate
Low
Types of effects mutation has on fitness
Neutral, e.g. at a non coding region, deleterious, beneficial
Characteristics of Mutation
- Inevitable: every single biological organism on earth has
- Random with respect to fitness
- Rate depends on type. gene and environment
4 Types of Mutations
Point mutations, insertions/deletions, changes in re[eat number and chromosomal rearrangements (inversions)
Mutation: Point Mutation
Single change in purine/pyrimidine base, a base substituted for another
Mutation: Insertions/Deletions
(Indels) change in length: one more/less base added/removed
Mutation: Change in Repeat Number
A motif repeated over and over again: loses track in the number of times repeated
Mutation: Chromosomal Rearrangements
Double strand break: doesn’t know which end is which, the strand is inverted
Silent Mutation and Amino Acids
If a mutation occurs on a non coding gene, or if the mutation codes for the same nucleotide, the mutation is silent
Independent Assortment
Allows different combinations of parental chromosomes to create a larger amount of possible progeny chromosomes
Calculate Independent Assortment
Two to the twenty three different gamete combinations, to to the forty six different zygote combinations
Recombination during Meiosis
Homologous chromosome pairs corss over at chiasmata, creating recombinant chromosomes that increase genetic diversity
2 False mechanisms of inheritance
Preformationism: one parent contributes only
Theory of Blending Inheritance: both parents equally
Problem with Theory of Blending Inheritance
No way for mutation to be passed on without being diluted
Mendel’s Experiments disproved what theory?
Theory of Blending Inheritance
Inheritance is determined by genes, x
Discrete particles
Polymorphism
Change in allele frequency
Incomplete Dominance vs Codominance
Incomplete: blend
Codominance: half half
Incomplete dominance is key to x
Genetic diversity
