ANTH 110 1nd Edition Lecture 7 Outline of Last Lecture I. Chromosomes II. Mendelian Genetics: The Laws of InheritanceOutline of Current Lecture I. Simple InheritanceA. Mendelian Traits in Humans II. Polygenic Inheritance III. Mendel's Two Basic Laws of Inheritance (or Mendel's Postulates)Current Lecture I. Simple InheritanceWhen a parent is homozygous for a trait, meaning they have two of the same alleles for a trait, they can only pass on that allele. If a parent is heterozygous for a trait, they can pass on either allele. For example, a parent who is homozygous for dimples can only pass down the allele for dimples. If he/she is heterozygous for dimples, he/she can pass down either the allele for dimples or the allele for no dimples. Punnett squares allow us to predict what the outcome may be. If two heterozygotes for a trait mate, they create a genotypic ratio of 1 TT: 2 Tt: 1 tt. In other words, there is 1/4 chance that their offspring will have TT combination, 2/4 chance their offspring will have Tt combination, and 1/4 chance their offspring will have tt combination. The phenotypic ratio of this particular situation would be 3 tall (TT, Tt, and Tt): 1 short (tt). If two homozygotes for a trait mate, they create a genotypic ratio of 4 Tt. The phenotypic ratio is 4 tall. Both parents must be heterozygotes for the offspring to have a chance of showing a recessive trait. A. Mendelian Traits in HumansOver 4,500 human traits are known to be inherited according to Mendelian principles. - simple traitsThese 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.- one genetic locus, or place on a chromosome (loci for plural)- two alleles, or alternate forms of one trait- three genotypes:- homozygous dominant- homozygous recessive- heterozygous- two phenotypes (either you have the trait or you don't)- create projections for these using Punnett squares- cannot be affected by the environment II. Polygenic InheritancePolygenic traits, or continuous traits, are governed by alleles at two or more loci, and each locushas some influence on the phenotype. Hair, eye, and skin color are polygenic traits. Conditions/diseases can also follow this pattern (e.g. High cholesterol).*polygenic traits = genetic potential +/- environment Continuous expression of a polygenic trait: the expression of height in a large group of people has a bell-shaped curve. Most people are closer to the average. Instead of only having two possible results, there are many possible results for polygenic traits. III. Mendel's Two Basic Laws of Inheritance (or Mendel's Postulates)1. The Law of Segregation:During the formation of gametes, the paired alleles separate or segregate randomly so that each sex cell receives one or the other with equal likelihood.i.e. Two alleles segregate into different gametes during meiosis such that each gamete only has one of the pair.2. Independent Assortment:During gamete formation, segregating pairs of alleles assort independently of each other. You get each trait independently of every other trait.i.e. Ear wax is not affected by height. Height is not affected by hair color. You receive each trait