Chapter 11 Intro to Genetics

Gregor Mendel and His Peas Fertilization in pea plants: asexual reproduction vs. sexual reproduction True –breeding vs. crossbreeding Identical traits vs. hybrid traits Gregor Mendel and His Peas

Passing of Traits to Offspring Genes control traits and are passed from parent to offspring Alleles are different forms of genes (describe genotype, dominant or recessive) Gametes – sex cells that contain the DNA /genes/traits that are passed to offspring

Segregation

Probability and Punnett Squares Flip a coin three times. What is the probability it will land heads up each time? ½ x ½ x ½ = 1/8 Cross a heterozygous tall (Tt) plant with a heterozygous tall (Tt) plant. In the F1 generation what is the probability of getting a tall allele and getting a short allele? In the F2 generation what is the probability of getting a tall offspring and short offspring?

Two Factor Cross and Independent Assortment Mendel was able to study two different genes at the same time by observing two different traits. Seed color and seed shape Mendel crossed round yellow seeds with wrinkled green seeds. Make a Punnett square showing the two factor cross using the genotypes RRYY and rryy This cross showed that the alleles segregated independently of each other. Examples of one-factor cross and two-factor cross on TB pg 268.

Summary of Mendel’s Principles Biological characteristics are inherited through units called genes. Genes are passed from parents to offspring. Sometimes there are two or more forms (alleles) of a gene for a single trait. Some forms of a gene may be dominant and others may be recessive. In most sexually reproducing organisms, each adult has two copies of each gene. Organisms get one copy from each parent. These alleles segregate from each other when gametes are made. Alleles for different genes usually segregate independently of each other.