Warmup 10/19/15 What does the word "genetics" mean? Objective Tonight’s Homework To learn basic ideas about genetics pp 127: 1, 3, 4

Notes on Mendel’s Experiments History of Genetics In the early 1800s, people didn’t know anything about inherited traits. They knew people looked like their parents, but not why.

Notes on Mendel’s Experiments History of Genetics In the early 1800s, people didn’t know anything about inherited traits. They knew people looked like their parents, but not why. In 1857, a monk named Gregor Mendel began to run some experiments. He began breeding different kinds of pea plants. As he did this, he carefully noted what traits were passed on and how.

Notes on Mendel’s Experiments This one man found out pretty much all the basics of genetics all by himself.

Notes on Mendel’s Experiments He experimented with 34 different kinds of peas and found 7 characteristics that seemed to be linked.

Notes on Mendel’s Experiments He experimented with 34 different kinds of peas and found 7 characteristics that seemed to be linked. Example: When he bred pea plants that had purple flowers to pea plants that had white flowers, all the new peas had purple flowers!

Notes on Mendel’s Experiments He experimented with 34 different kinds of peas and found 7 characteristics that seemed to be linked. Example: When he bred pea plants that had purple flowers to pea plants that had white flowers, all the new peas had purple flowers! He found the same thing for 6 other traits. One trait won out over the other every time!

Notes on Mendel’s Experiments Mendel’s Concepts Mendel continued to breed plants and found that patterns started to emerge after several generations. He came to 3 big conclusions.

Notes on Mendel’s Experiments Mendel’s Concepts Mendel continued to breed plants and found that patterns started to emerge after several generations. He came to 3 big conclusions. 1) Unit Characteristics. Characteristics can be uniquely separated and come in pairs. Mendel caused them “factors”, we call them “genes”.

Notes on Mendel’s Experiments Mendel’s Concepts Mendel continued to breed plants and found that patterns started to emerge after several generations. He came to 3 big conclusions. 1) Unit Characteristics. Characteristics can be uniquely separated and come in pairs. Mendel caused them “factors”, we call them “genes”. A tall pea plant could have its genes for tallness represented by “TT”. A short pea plant could have its genes for tallness represented by “tt”. We can have “Tt”, but we’ll get to that…

Notes on Mendel’s Experiments 2) Dominant and Recessive. When Mendel crossed purple flowers with white flowers, he found that all the plants in the next generation had purple flowers. All of them.

Notes on Mendel’s Experiments 2) Dominant and Recessive. When Mendel crossed purple flowers with white flowers, he found that all the plants in the next generation had purple flowers. All of them. If he had pure tall plants, their genes would have been “TT”. The pure short plants would have genes like “tt”.

Notes on Mendel’s Experiments 2) Dominant and Recessive. When Mendel crossed purple flowers with white flowers, he found that all the plants in the next generation had purple flowers. All of them. If he had pure tall plants, their genes would have been “TT”. The pure short plants would have genes like “tt”. So when they mixed, they could have had genes like “Tt”. But instead of making medium plants, the plants were just tall. Mendel said that tallness was a dominant trait and shortness was a recessive trait. Dominant traits show, recessive ones don’t.

Notes on Mendel’s Experiments 3) Segregation. Mendel figured out how genes combine. Each plant has 2 for a given characteristic. One is randomly picked and combines with one randomly from the other plant. We call each of these 1 a “gamete”.

Notes on Mendel’s Experiments 3) Segregation. Mendel figured out how genes combine. Each plant has 2 for a given characteristic. One is randomly picked and combines with one randomly from the other plant. We call each of these 1 a “gamete”. Example: tallness Plant 1 Plant 2 T Tt t T t One of the two gametes is picked randomly from each parent. They then combine in the new plant, making the new gene.

Vocabulary Two things that have the same structure; similar things in the same place, but aren’t identical. A chunk of DNA that codes for a single trait. Can usually be dominant or recessive. A pair of gametes. All living organisms have their gametes in pairs as genes. The overall result we get when we combine two gametes. Usually what we see. The genes an organism has. Example: “Tt” could be a genotype, “tall” would be its phenotype. Homologous Gamete Gene Phenotype Genotype

Vocabulary (Pronounced “uh-leel”) A pair of genes that are on the same position in homologous DNA. These are linked. These are the letters we write. Similar to gametes. When both alleles in an organism are the same. Like “TT” or “tt”. When both alleles in an organism are different. Like “Tt”. When genes combine with only one pair at a time. We’ve seen only this so far, but things like blood type have genes more like “I B i”. Allele Homozygous Heterozygous Monohybrid

Exit Question What is a dominant trait? a) When a creature has 2 genes of the same type. b) When one gene suppresses another c) When genes are homologous d) The phenoype e) When we have a monohybrid cross f) None of the above