Genetics

The Chromosome Chromosomes are types of genetic material What type of organic molecule are chromosomes? What does Genetic Material do? Where is the genetic material found? What are the subunits of genetic material? How do they store this information? How many chromosomes do you have? How did you get this number?

Fertilization

Its all in your Genes What is a Gene? A gene is the carries the information for your traits. What are examples of traits? Ok, so eye color is a trait, there is a gene for eye color. Are all genes the same?

Alleles The word you will come to love!! The different forms of a gene are called alleles. What are the different alleles for the eye color gene? What are the different alleles for other genes?

Chromosomes, Genes, and Alleles all put together Ok, so…… You have 46 Chromsomes Each Chromosome carries a certain amount of Genes Each person has the genes in the same places. So, why, if we have the genes in the same places do we not all have the same traits? Because of Alleles!!!

Karyotype

Let’s Look at Pea Plants Yes, I said pea plants! (I know, it sounds exciting) Gregor Mendel studied pea plants in his garden. He chose them to study because: They grow fast They have traits that are easy to study Peas reproduce sexually (what does that mean?) Here are the traits that we are going to study about pea plants: They are either tall or short - what is the gene, and what are the alleles? They are either yellow or green – what is the gene and what are the alleles? The are either shriveled or round – what is the gene and what are the alleles?

How do you know which allele you will show up in you? You get your genes from your parents Remember, each person has 2 sets of genes. They might have the same allele for each gene, but they also might have different alleles for each. Each parent gives you 1 of their alleles for each gene. How do you know which one will show up in you. For example: So, say I crossed a tall plant with a short plant, is that plant going to be tall or short? To answer that we have to know some more about genes!!

More on Alleles Some genes are dominant – meaning, if they are there they are going to show up no matter what!!! Use a Capital letter to notate a dominant gene Some genes are recessive – meaning, if they are there they are only going to show up if a dominant one is NOT there Use a lower case letter to notate a recessive gene So, what does that mean for us?

Dominance and Recessive So, lets look at the plant problem again. I want to know if I mate a tall plant with a short plant, will the offspring be tall or short? Tall is Dominant and Short is recessive. The gene for height we will notate with a letter T T = Tall (capital for dominant) t = short (lower case for short) This problem is going to depend on which alleles the tall plant has.

Homozygous and Heterozygous What alleles could the tall plant have? If it is tall, it is going to have a tall allele for the height gene. Are both of its height gene going to be tall? It could be TT. If it is TT, will it be tall or short? Why? We call this homozygous Dominant because both alleles are the same, and they are both dominant alleles. It could also be Tt. Why will this plant not be short? We call this heterozygous because the genes for the height allele are different What alleles could the short plant have? The short plant has to be tt. We call this homozygous recessive because both alleles are the same, and they are both recessive.

The Human Genome Project The Human Genome project’s goal was to map out where genes in humans are There is a chromosome map now. What would some benefits be to have a chromosome map?

Biology Warm Up What is the difference between a gene and an allele? A person can have blue eyes, brown eyes, or green eyes. What is the gene in this example and what are the alleles? If the gene for pea color is represented by the letter Y. If yellow is dominant how is it represented? If green is recessive how is it represented? Write what the genes for pea color for a homozygous dominant pea plant would look like Write what the genes for pea color for a heterozygous pea plant would look like Write what the genes for pea color for a recessive pea plant is. How many chromosomes do you have? How many different chromosomes do you have?

36.3 Chromosome 1 36.2 36.1 35 34.3 34.2 34.1 33 32.3 32.2 32.1 31.3 p 31.2 31.1 22.3 22.2 22.1 21 13.3 13.2 13.1 12 11 11 12 21.1 21.2 21.3 22 23 24 25 q 31 32.1 32.2 32.3 41 42.1 42.2 42.3 43 44

How do These genes get from organism to organism? They get passed down from through sexual reproduction Each organism gives one of their genes to the offspring. How do they do this? They create sex cells called gametes. What are the examples of sex cells (gametes)? These cells only have 1 set of genes in it. They are created through meiosis

Meiosis Meiosis is very similar to Mitosis, but it produces very different results. What was my goal/products of mitosis? The goal for Meiosis is to produce 4 different cells, with only 1 copy of each chromosome.

Haploid and Diploid Haploid (n) – a cell with only 1 of each chromosome Diploid (2n) – a cell with 2 of each chromosome. They will have 2 chromosomes with the same genes, but are these chromosomes identical? NO!! Why? So, the gametes are haploid and all other cells are diploid. In mitosis we produce 2 identical diploid cells and in meiosis, we produce different 4 haploid cells.

A little bit more Terminology When a diploid cell has 2 of each chromosome, we say that they are Homologous Chromosomes Are Homologous chromosomes identical? What is the same about homologous chromosomes?

So What is Meiosis?

Some Drawings… Open to page 267 and draw Meiosis I and Meiosis II in your notes. Be sure to label each individual phase. When you are finished, complete The Basis of Heredity worksheet using your notes and the book (pages 263-273). We will go over this together, then draw some more pictures, then complete a meiosis reinforcement review.

Biology Warm Up Where does crossing over occur? In Meiosis 1 of Meiosis 2 do the homologous chromosomes get split apart? What are the results of meiosis? How do these results compare with the results of mitosis? What are gametes?

Punnet Squares How do I find out what chances we have to pass down specific traits? We will need to use a punnet square On the outside of the square I put the potential gametes that could be made On the inside I write the potential offspring. How were the gametes made?

Biology Warm Up