Meiosis, Reproduction, and Inheritance Unit 7 At this point in our studies, we have examined the Central Dogma (DNA makes RNA makes protein), the concept of genes, and the reality that the genes our cells express play a big role in what makes each of us unique. We have seen how cells divide, and we will learn that, thanks to meiosis, when male and female gametes fuse to form an embryo, the offspring inherit the traits of the parents.

Entry Task: Lab Notebook 3/31/15 Before you introduce yourself to your new table partner, write at least one paragraph description of who you are. What makes you…you? Partner Share: Introduce yourselves. Take careful notes in your lab notebook about how your partner describes themselves.

Our Road Map Cell Division Mitosis Meiosis Heredity Traits Replication Chromosomes DNA Genes RNA Protein

Crash Course: Heredity https://www.youtube.com/watch?v=CBezq1fFUEA

Gregor Mendel (1822-1884) The Father of Genetics Mendelian Genetics 9/20/2018 Gregor Mendel (1822-1884) The Father of Genetics Some of you may recall the story of Gregor Mendel. Today he is known as the father of genetics. He was born nearly 200 years ago and spent his adult life as an Austrian monk studying pea plants. copyright cmassengale

Gregor Johann Mendel Austrian monk Mendelian Genetics 9/20/2018 Gregor Johann Mendel Austrian monk Studied the inheritance of traits in pea plants Developed the laws of inheritance Mendel's work was not recognized until the turn of the 20th century

copyright cmassengale Mendelian Genetics 9/20/2018 Gregor Johann Mendel Between 1856 and 1863, Mendel cultivated and tested thousands of pea plants He found that the plants' offspring retained traits of the parents copyright cmassengale

Particulate Inheritance Mendelian Genetics 9/20/2018 Particulate Inheritance Mendel stated that physical traits are inherited as “particles” Mendel did not know that the “particles” were actually Chromosomes & DNA copyright cmassengale

copyright cmassengale Mendelian Genetics 9/20/2018 Why peas, Pisum sativum? Can be grown in a small area Produce lots of offspring Produce pure plants when allowed to self-pollinate several generations Can be artificially cross-pollinated copyright cmassengale

Mendel tested 7 traits: Flower color Flower position Seed color Seed shape Pod shape Pod color Plant height Mendel carefully recorded the results of hundred of plant breeding experiments. He studied his results and concluded that certain traits were expressed in certain ratios. http://www.fieldmuseum.org/exhibits/traveling_mendel.htm

Mendel and His Peas Mendel crossed flowers that were true-breeding for each characteristic. He crossed a purple (PP) flowered plant with a white (pp) flowered plant. (Parent Generation) Phenotype Genotype PP or Pp pp

Mendel and His Peas Purple Parent (PP) The first generation (F1) of plants all had purple flowers. Where did the white color go?? White Parent (pp)   (Pp)    (Pp)    (Pp)

Mendel and His Peas Mendel took two of his first generation (F1 x F1) purple flowered plants and crossed them together. In the second generation (F2) he had 3 purple flowered plants, and 1 white flowered plant. Purple Parent (Pp) Purple Parent (Pp)    (PP)   (Pp)   (Pp)   (pp)

Mendel and His Peas Mendel noticed in the first generation, all of the white flowers seemed to disappear. He called this a recessive trait. The white color faded into the background at first. It showed up in the next generation when he pollinated the flowers.

Mendel and His Peas The color (purple) that seemed to mask over the recessive color was named the dominant trait.

Mendel and His Peas Mendel was responsible for figuring out that each plant carried two sets of instructions for each characteristic (one from the “mom” and one from the “dad”). Like many scientists, his work was not accepted until after his death.

What are the odds? Select one of your traits from the entry task Given your own phenotype, as well as your parents, can you determine your genotype for that trait? How about for your parents? Create a Punnett Square based on your parent’s predicted genotype. What are the odds that you would have inherited the trait you possess?