Lab 11 - Population Genetics

BIO 112 - Dr. Shauna Price

What is evolution?

The change in organisms over time that can be studies at a small or large scale.

What is small-scale evolution?

Changes in a population from generation to generation (population genetics).

What is large scale evolution?

Changes in species or bigger taxonomic groups over long periods of time (phylogenetics).

What is a population?

Interbreeding groups of an organism of the same species living in the same geographical areas that make up a species.

What is population genetics?

The study of genetic changes in populations over time.

What is genetic variation?

The differences in DNA sequences between individuals within a species.

What is an allele?

Different variations of different versions of a gene.

What is a genotype?

The alleles an individual has that code for a particular gene.

What is a phenotype?

The observed characteristics that the allele combinations of a gene present in an organism.

What is evolution in terms of the genetics of it?

A change in allele/genotype frequency in a population from on generation to the next.

What is genotype frequency? How is it calculated?

How often we see each allele combination present in a generation, calculated by the amount of times a combination is present in a generation divided by the total number of genotypes.

What is phenotype frequency?

How often we see a each observed characteristic of an organism in a generation, calculated by the amount of times a characteristic is present in a generation divided by the total number of organisms.

What is allele frequency? How is it calculated?

How often a certain allele is present in a generation, calculated by the amount of each allele present in a generation divided by the total alleles present.

What equation is can be used to find allele frequencies?

p+q=1.

What do the variables mean in the equation that can be used to find allele frequencies?

p = frequency of dominant allele

q = frequency of recessive allele

What is a model? What are they used for?

A description of a system using mathematical equations used to assess whether evolution is occurring or not.

What is the Hardy-Weinberg equilibrium?

A model used to make predictions about allele and genotype frequencies is a population is NOT evolving meaning no changed in allele/genotype frequencies from generation to generation.

What is the H-W equation?

p²+2pq+q²=1.

What do each of the variables of the H-W equation represent?

p² = frequency of dominant genotype

2pq = frequency of heterozygous genotype

q² = frequency of homozygous recessive genotype

How is H-W used?

To compare whether expected frequencies predicted by HWE are different from the observed, if they do not match then the population is evolving.

What are the 5 conditions of the H-W equilibrium?

1. NO mutations

2. NO gene flow

3. Random mating

4. NO genetic drift

5. NO natural selection

If all of these are met then the population is NOT evolving and at H-W equilibrium if even just one is not met then the population is evolving.

What is the condition NO mutation?

No new alleles are introduced to the population.

What is the NO gene flow condition?

No movement of individuals (and their alleles) from one population to the other.

What is the random mating condition?

Individual’s choice of mate is not related to their genotypes.

What is the NO genetic drift condition?

Random chance events cause changed in allele/genotype frequencies, is not realted to the organisms traits, and the larger the population is the less chance of alteration in frequencies.

What is the NO natural selection condition?

No difference in the survival/reproductive success of individuals.

What is natural selection?

The process where individuals with certain inherited traits survive at higher rates than others therefore their alleles pass to the next generation.

What is a simulation?

A study where you set up pretend scenarios to approximate real world conditions.

What causes sickle cell disease?

A mutation in the gene that codes for the hemoglobin protein.

What does the mutation in the hemoglobin protein cause for the red blood cells?

They affect them to where they can’t carry enough oxygen so they become cresent-like shapes.

What are the meanings of the different sickle cell genotypes?

AA: Normal red blood cells

AS: Cell abnormality but not sickle cell

SS: Sickle cell disease

Where is sickle cell most common? Why?

Sickle cell disease is most commonly found in regions like Africa where malaria is more common since having this trait can protect people from malaria.

What climate is malaria most common in? Why?

Malaria is most common in moist environments since mosquitoes need water to reproduce.