Introduction to Meiosis 6.2 MA 2.7 Meiosis in sexual reproduction. 3.4 Genetic traits result in observed inheritance patterns. Chapter 6 in the Big Black Book pages

*two page notebook format* Do Now: 1) Why are siblings (brothers and sisters) with the same parents so different? 2) If your mother has 46 chromosomes in her cells, and your father has 46 chromosomes in his cells, how many chromosomes are in your cells? How is that possible? 3) Science Skill: Interpreting bar graphs. Solve #1, 2, 3 on page 162. Topic: Meiosis and Mendel Objectives, language objectives : Objectives, language objectives: Describe how haploid cells develop into mature gametes. Describe how haploid cells develop into mature gametes. Compare and contrast the two rounds of division in meiosis. Compare and contrast the two rounds of division in meiosis. Language Objectives: Use the terms body cells, gametes, autosomes, sex chromosomes, haploid, diploid, homologous chromosome, autosome, sex chromosome, sexual reproduction, gametogenesis, sperm, egg, polar body, and meiosis orally and in writing. Use parent cell and daughter cell in discussion. (all week) Page 55 Tuesday, Dec 16, 2014 Page 56

Why are siblings (brothers and sisters) with the same parents so different?

If your mother has 46 chromosomes in her cells, and your father has 46 chromosomes in his cells, how many chromosomes are in your cells? How is that possible?

Science Skill: Interpreting bar graphs. Solve #1, 2, 3 on page 162. (see handout) Practice – interpret a bar graph: 1) Analyze: Which organism has the greatest number of chromosomes? The least? 2) Evaluate: Does chromosome number appear to correlate to the type of organism? 3) Hypothesize: Do you think there is an upper limit to chromosome number? Explain?

Body Cells and Gametes Your body cells are the cells of your body. Gametes are special cells used only for one purpose – sexual reproduction. These are the sperm and egg cells, which do no work at all towards the maintenance and function of your body. Gametes are special cells used only for one purpose – sexual reproduction. These are the sperm and egg cells, which do no work at all towards the maintenance and function of your body.

Your cells have autosomes and sex chromosomes. Predict: What do you think is the difference? Your cells have autosomes and sex chromosomes. Predict: What do you think is the difference? Autosomes Chromosomes that are NOT directly related to the sex of an organism. Homologous chromosomes are two chromosomes (one from each parent) that have the same size and the same genes on each. In people, chromosomes 1-22 are the autosomes. Sex Chromosomes The set of chromosomes that directly control the development of sexual characteristics. In humans and all mammals, the XY system determines sex. XX = female and XY = male. The X is larger and contains more genetic information. Y is smaller with fewer genes. The sex chromosomes are pair 23. (See figure 1.1 on page 159)

Body cells are diploid ; gametes are haploid compare Mitosis and Meiosis figure 1.2 page 161 Body cells are diploid; gametes are haploid compare Mitosis and Meiosis figure 1.2 page 161 Mitosis Work in pairs Answer “Compare” in notebook on left side Meiosis Use a T chart and illustrations Answer “Apply” in notebook on left side

Homologous chromosomes and sister chromatids Cells go through two rounds of division in meiosis. Homologous chromosomes are divided in meiosis I. Sister chromatids are divided in meiosis II

6.2 Process of Meiosis: During meiosis, diploid cells undergo two divisions that result in haploid cells Meiosis I (page 164) What is the beginning point of Meiosis I? What is “reduced” in this part of “reduction division”? What is the result? Meiosis II (page 165) What is the beginning point of Meiosis II? What is “reduced” in this part of “reduction division”? What is the result? What is the major difference between Metaphase I and Metaphase II? Model – shoes activity

6.2 Formative Assessment Answer questions 1-3 on page 166. SUMMARIZE what you learned today in 3-5 sentences Homework: Study Guide 6.2 – selected questions depending on today’s progress in class. If not done, complete cells Standards Based Assessment Quiz Review Greek and Latin word roots Make up take home Greek and Latin quiz if not taken in class

Genetics Project coming soon! A Sickeningly Sweet Baby Boy: A Case Study on Autosomal Recessive Inheritance