Biology1/9/14 Mrs. Turgeon “In three words I can sum up everything I’ve learned about life: It goes on.” – Robert Frost Do Now: Do Now: 1. In your notes: How many chromosomes does a human somatic cell have? What about a human gamete? Agenda: 1. Review dihybrid quiz 2. Students will be able to describe the stages of meiosis by taking notes and working with their partners Homework: 1. Study for final exam- study guide is on-line!

Biology1/8/14 Mrs. Turgeon “This is what I learned: that everybody is talented, original and has something important to say.” –Brenda Ueland Do Now: 1. Place any late work in the late folder 2. Get into your POGIL groups and wait for instructions Agenda: 1. Students will be able to describe the stages of meiosis by taking notes and working with their partners Homework: 1. Study for final exam- study guide is on-line!

Biology1/13/14 Mrs. Turgeon “If you tell the truth, you don’t have to remember anything.” - Mark Twain Do Now: 1. In your notes: define osmosis. Agenda: 1. Students will be able to prepare for their semester 1 exam by working on the study guide with their partners Homework: 1. Study for final exam- study guide is on-line!

Meiosis Chapter 10, Section 2

Meiosis Activity 1. You need one textbook for every two students. 2. You will be taking notes from the screen and using your textbook.

Genes and Chromosomes Punnett squares help us to study a few genetic traits at a time Organisms actually have tens of thousands of genes that make each of us unique Genes are lined up on chromosomes One chromosome can contain a thousand genes along its length

Turn to page 265 in the textbook With your partner, find the bold word: meiosis. Read about meiosis and answer the following questions. Be prepared to share your answers with the class! 1. Does meiosis occur in liver, heart, and skin cells? 2. Why is it important for organisms to produce cells with HALF the number of chromosomes?

Diploid & Haploid Cells Diploid = a cell with two sets of chromosomes, 2n Haploid = a cell with one set of chromosomes, gametes, 1n Meiosis forms haploid gametes required for sexual reproduction Meiosis has 2 stages –Meiosis I –Meiosis II

Turn to page 265 Study Table 10.1 Chromosome Numbers of Common Organisms and answer the following questions with your partner. Be prepared to share your answers. 1. What does the n stand for in the table? 2. Look at the data for the leopard frog. Why is the number in the body cell column double the number in the gamete column?

 MEIOSIS I Separation of homologous pairs Homologous Pair = in a diploid cell the 2 sets of chromosomes pair up

 1. Prophase I DNA coils into chromosomes Nuclear envelope & nucleolus break down Synapsis = homologous chromosomes pair up into tetrads Crossing-over = homologous pairs switch pieces of their chromatids Genetic Recombination = maternal & paternal genetic info get shuffled during crossing-over

Turn to page 269 Study Figure and answer the following questions. Be prepared to share your answers! 1. Are sister chromatids identical or different to each other? What about homologous pairs? 2. In part C, if you put the four chromosomes back into pairs, would they be the same as the original Homologous chromosomes in part A?

 2. Metaphase I Tetrads line up in the middle of the cell Spindle fibers attach at the centromeres of each homologous chromosome

Homologous chromosomes line up side by side as tetrads

 3. Anaphase I Each homologous chromosome moves to the opposite end of the cell Independent Assortment = random separation of chromosomes, allows for genetic variation

 4. Telophase I & Cytokinesis I Two newly formed cells are haploid Each chromosome is still made up of two chromatids

Humans have 46 chromosomes (23 pairs) With your partner, discuss what would happen if the formation of gametes stopped after meiosis I. How many chromosomes would the resulting human end up with? Be prepared to share with the class!

 MEIOSIS II Separation of sister chromatids Sister Chromatids = identical halves of a chromosome that has been duplicated

 5. Prophase II 2 newly created cells from Meiosis I start to divide

 6. Metaphase II Chromosomes line up in the center

 7. Anaphase II Sister Chromatids separate

 8. Telophase II & Cytokinesis II 4 new cells, each with half the number of chromosomes of the original cell

Development of Gametes Spermatogenesis = production of sperm cells Oogenesis = production of mature egg cells

Turn to page 269 Read the section titled Meiosis Provides for Genetic Variation and answer the following questions: 1. Describe the major difference between cells formed by mitosis and cells formed by meiosis. 2. What is “variability” and why is it important to us?

Biology1/10/14 Mrs. Turgeon Do Now: Do Now: 1. In your notes: How many cell divisions occur during mitosis? What about during meiosis? Agenda: 1. ACT Quiz 2. Students will be able to describe the stages of meiosis by taking notes and working with their partners Homework: 1. Study for final exam- study guide is on-line!

Finals Schedule Jan. 14Jan. 15Jan st 8:30 – 9:301 st 8:30 – 9:12 2 nd 9:34 – 10:162 nd 9:16 – 10:162 nd 9:16 – 9:58 D. 10:02 – 10:12 3 rd 10:20 – 11:02 3 rd 10:16 – 11:16 4 th 11:06 – 12:064 th 11:06 – 11:484 th 11:20 – 12:02 5 th 12:10 – 12:525 th 11:52 – 12:525 th 12:06 – 12:48 6 th 12:56 – 1:38 6 th 12:52 – 1:52 7 th 1:42 – 2:427 th 1:42 – 2:247 th 1:56 – 2:38 8 th 2:46 – 3:288 th 2:28 – 3:288 th 2:42 – 3:24

Nondisjunction Nondisjunction = failure of homologous pairs to separate in Meiosis I If an organism survives, it may have a genetic disorder

Polyploidy Polyploid = organisms with more than the usual number of chromosome sets Occurs frequently in plants, results in plants that are larger than normal