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What is an Allele?
Alternative forms of a gene.
What does Genotype mean?
- What alleles you have.
- Phenotype: What you look like, or what is expressed. (In the case
- of plants. Being short is the phenotype. Since short is recessive, we know that
- the plant carries two short alleles (tt). This is the genotype.) Sometimes you
- can’t tell the genotype just from looking at the phenotype.
What does Homozygous mean?
- Homozygous: Having two of the same allele. You can be either
- homozygous dominant (TT) or homozygous recessive (tt)
What does Heterozygous mean?
Heterozygous: Having one of each allele for a gene. (Tt)
Explain the Law of independent assortment:
- Law of independent assortment: Different genes are sorted
Explain Law of segregation:
- Law of segregation: Each of the offspring are only going to get one
- allele from each parent.
What does Linked Genes refer to?
- Linked Genes: Genes that are located on the same chromosome.
- Violates the law of independent assortment. If you are reading this before next
- class, I just jumped ahead of myself. This is the reason we didn’t get the
- ratios we expected in the fruit flies.
What is a Monohybrid cross?
- Monohybrid cross: A cross focusing on one gene, like the one
- pictured below.
What is a Dyhybrid cross?
- Dyhybrid cross: A cross with two genes, like the one we did in
- class with the fruit flies
For Hardy Weinberg to be true, or a species be in equalibrium with Hardy Weinberg what also must be true?
No Gene Flow (Migration)
No Genetic Drift
No non-random mating
(Most of these are opposite of the Natural Selection postulates)
One of the Hardy Weinberg Assumptions is: "No Selection"; what does that mean?
No Selection- To prevent natural selection from happening, there can’t be differential fitness.
One of the Hardy Weinberg Assumptions is: "No Gene Flow"; what does that mean?
No Gene Flow (Migration)- In order for gene frequencies to be the same, the gene pool can’t be altered due to immigration and emigration.
One of the Hardy Weinberg Assumptions is: "No Genetic Drift"; what does that mean?
No Genetic Drift- The key to this is SMALL POPULATION. There are two types:
Founder effect: A tiny portion of a population leave and found their own population (for the old population, this is gene flow. We are now focusing on the tiny new population, which has very different genetics than the old population. (Example: Lehi leaving Jerusalem. Whoever said that, you are brilliant.)
Bottle-neck: Taking a population and wiping out most of them so only a few are remaining.
One of the Hardy Weinberg Assumptions is: "No non-random mating: "; what does that mean?
No non-random mating: This is like a double negative. To rephrase, you have to have random mating for Hardy-Weinberg to hold true. The ladies can’t have a preference, and let’s be honest, that’s never true.
One of the Hardy Weinberg Assumptions is: "No mutation"; what does that mean?
No mutation: This one is pretty self-explanatory. If there is no mutation, the population can’t evolve.