Lecture 23Outline of Last Lecture1. Define the terms phenotype, genotype, locus, allele, dominant allele, recessive allele, homozygous, and heterozygous.2. Describe Mendel’s Laws (principles) of segregation and independent assortment.3. Solve genetics problems involving monohybrid, dihybrid, (trihybrid) and test crosses.Outline of Current Lecture1. Be able to solve any punnett square genetics problem.I. Punnett SquaresWith punnett squares, all that is required is box method cross multiplication. This can be more complicated as you have more than 4 alleles, however. Below are some examples.Above is a simple 4 allele problem. These can be done quickly and easily and are self-explanatory. They call this one specifically a 1:2:1 punnett square. It’s called this because there’s a ¼ chance of homozygous dominant alleles in the genotype, a 2/4 chance of a heterozygous alleles, and a ¼ chance of homozygous recessive alleles.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. BIOL 101 1st EditionThis however is not so nice. When you deal with more than 2 pairs of alleles, you make a 16x16 square, but this is time consuming and is very error prone so it isn’t recommended. If you do need to use a punnett square to figure a problem out, make small 2x2 punnett squares to figure it out instead of one big mess.After you make multiple small punnett squares, you can multiply the chances togetherto find the chance of a specific phenotype. In this punnett square, we can see a ¼ chance of getting homozygous recessive alleles in the phenotype. To find out the chance of getting two recessive alleles in two different genes, all you have to do is multiply the chance of getting both alleles. For example this one is a ¼ chance of homozygous recessive alleles.This one also is a ¼ chance of homozygous recessive alleles.Therefore, if you multiply them together, there is a 1/16 chance of getting both homozygous recessive alleles in the genotype. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. BIOL 101 1st
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