Lecture 4 Flashcards
Population Genetics
What is population genetics?
The study of genes and genotypes in a population.
This helps us understand how genetic variation is related to phenotypic variation
Also helps us understand the extent of genetic variation, why it exists, maintained and how it changes over the course of many generations
What is a gene pool?
All of the alleles for every gene in a given population
It is the study of genetic variation within the gene pool and how variation changes from one generation to the next
Emphasis is often on variation in alleles between members of a population
What is a population?
It is a group of individuals of the same species that occupy the same environment and can interbreed with one another
Some species occupy a wide geographic range and are divided into discrete populations
Populations can change in size and location; leads to changess in genetic composition
What is polymorphism?
Two or more variations for a given character
Due to two or more alleles that influence phenotype
What is a polymorphic gene
Two or more alleles
What is a monomorphic gene
Predominantly single allele
What is a single nucleotide polymorphisms
The smallest type of genetic change in a gene
Also the most common - 99% of variation in human gene sequences
Why is the analysis of SNPS so important
Important for personalized medicine - patients genotype used to tailer his or her medical care
How do you calculate the allele frequency?
number of copies of a specific allele in a population / Total number of alleles for that gene in the population
How do you calculate the genotype frequency?
Number of individuals with a particular genotype in a population / Total number of individuals in the population
What is the Hardy-Weinberg Equilibrium
Predicts that allele and genotype frequencies will remain the same, generation after generation, provided that a population is in equilibrium
To be in equilibrium, population must not be affected by evolutionary mechanisms that change allele and genotype frequencies
What are the conditions for the Hardy-Weinberg Equilibrium
No new mutations occur
No natural selection occur
The population is so large that allele frequencies do not change due to random chance
No migration occurs between different populations
Random mating occurs
In reality, no population meets these conditions
What does it mean when the frequencies in the Hardy-Weinberg Equilibrium are not in equilibrium
An evolutionary mechanism is at work
What is mircoevolution
Changes in a population’s gene pool from generation to generation
Why does mircoevolution change
Introduces new genetic variation (mutations, gene duplication, horizontal gene transfer)
Not a major factor dictating allele frequencies
