Transcript Meiosis ppt
Bellwork – Monday 9/23 During which phase of the cell cycle does DNA replicate? Why does the DNA have to replicate before cell division? How many daughter cells are produced from mitosis? How do the cells at the end of mitosis compare the cells at the beginning of mitosis? If a salamander tail cell has 24 chromosomes, how many chromosomes should the cell have after mitosis? When in the cell cycle does cytokinesis begin? Label the parts of the chromosome in the Diagram. Wednesday bellwork The graph at left shows the cell cycle of a liver cell. How long does the cell cycle of a liver cell take Which phase of the cell cycle does the cell spend the most time in? List 3 things that happen in interphase If a liver cell has 46 chromosomes before mitosis how many should it have after mitosis? Bellwork: 1. 2. 3. 4. 5. 6. 7. Draw Interphase and Prophase. Describe the difference between these 2 phases Draw a chromosome and label the centromere and chromatids A cell normally has 36 chromosomes, how many will it have after mitosis What are the new cells from mitosis called List the phases of mitosis in order What divides in mitosis? What divides in cytokinesis? http://www.neok12.com/Cell-Division.htm http://www.youtube.com/watch?v=pOsAbTi9tHw After the quiz In the green book, read the article on Cancer research on p. 340 then answer the following questions Describe Cobb’s experiment on Cancer cells. What was her independent and dependent variable Describe how Levy was working to understand cancer. What were her independent and dependent variables? Bellwork 9/26 1. 2. 3. 4. 5. 6. 7. When does the cell’s nucleus divide into 2 new nuclei? When are 2 new daughter cells formed? Why do single celled organisms have cell division? Why do multicelluar organisms undergo cell division? What processes happen during the cell cycle? During which phase of mitosis do you first see chromosomes? See 2 nuclei with visible chromosomes? You are looking at a cell and the genetic material looks like a tangled ball of string, what is it called? What phase is it? Meiosis EQ: How do cells divide for sexual reproduction Sc.7.L.16.3 – compare mitosis and meiosis What is sexual Reproduction? A type of reproduction in which the genetic material from 2 different cells combine to produce offspring Sex cells – the cells that combine in sexual reproduction – sperm and egg. (also called gametes) What is chromosome number? Chromosome number – every organism has a set number of chromosomes In fruit flies there are 8 chromosomes In humans there are 46 chromosomes What are homologous chromosomes? Homologous chromosomes are pairs of chromosomes found in body cells that are the same size and carry the genes for the same trait How do sex cells and body cells differ? Body Cells: Formed by mitosis Are called diploid because they contain both homologous chromosomes They have both of the homologous chromosomes Produced by asexual reproduction In a human they have 46 chromomes In a fruit fly = 8 chromosomes How do sex cells differ from body cells Sex Cells Formed by meiosis Are called hapliod because they have half the homologous chromosomes – only 1 chromosome from each homologous pair Formed by sexual reproduction In a human they have 23 chromosomes In a fruit fly they contain 4 chromosomes Fruit flies have 8 chromosomes in each body cell They have 4 chromosomes in each sex cell diploid haploid Why do organisms need sex cells? When the 2 cells combine in sexual reproduction they get ½ of there chromosomes from each parent organism making a complete set. How are sex cells made Body cells are formed by mitosis, sex cells are formed by meiosis Meiosis - a type of cell division that produces sex cells such as egg and sperm chromosome number of different organisms. How many chromosomes would be in a sex cell from these organisms? How many chromosomes would be in a body cell from these organisms? The cell shown is a body cell. Draw a sex cell for the same organism What are the stages of meiosis? Meiosis involves 2 divisions of the cytoplasm called Meiosis 1 and Meiosis 2 Turn and talk Name some ways that meiosis is different from mitosis Parts of Meiosis Meiosis 1 • Chromosome number decreases as homologous pairs separate Meiosis 2 • Chromatids separate and move to opposite ends of the cells Meiosis coloring foldable: Directions: 1. 2. 3. 4. Label all key structures (homologous chromosomes, centromere, nuclear membrane, nucleus- ). 2 points Label Meiosis I and Meiosis II at the top of the pages 1 point Write a brief description of each phase– use the handout or the link from the website 8 points Color each chromosome. Choose 2 different colors: Color one homologous pair of chromosomes dark ________________ and light __________________. Choose the same color. Color the other homologous pair of chromosomes dark ________________ and light __________________. Choose the same color, but different from step a. DON’T forget to color your chromosomes accurately throughout all of the phases. (4 points) Meiosis Interphase The chromosomes have replicated, and the chromatin begins to condense. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html Meiosis Prophase I http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html Meiosis Metaphase I http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html Meiosis Anaphase I http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html Meiosis Telophase I & Cytokinesis http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html Meiosis Prophase II http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html Meiosis Metaphase II Meiosis Anaphase II Telophase II & Cytokinesis Bellwork: are the following characteristics of mitosis, meiosis or both – create a Venn Diagram 1. Produces 2 identical cells 2. Produces haploid cells 3. Used for growth and repair 4. Produces 4 cells 5. Produces diploid cells 6. Chromosomes line up in the middle of the cell 7. Used for creation of gametes 8. Homologous pairs line up 9. Contains prophase, metaphase, anaphase and telophase (PMAT) Meiosis Meiosis animation: tp://www.youtube.com/watch?v=D1_-mQS_FZ0&NR=1 sis animation http://www.youtube.com/watch?v=VlN7K19QB0&feature=bf_prev&list=ULD1_-mQS_FZ0 osis square dance //www.youtube.com/watch?v=JKXAdwCibsA Mitosis vs. Meiosis How do mitosis and meiosis differ? During mitosis and cell division, a body cell and its nucleus divide once and produce two identical diploid cells. The two daughter cells produced by mitosis and cell division have the same genetic information. How do mitosis and meiosis differ? During meiosis, a reproductive cell and its nucleus divide twice and produce four cells—two pairs of identical haploid cells. Meiosis forms sex cells used for sexual reproduction. Mitosis Meiosis How does meiosis compare to Function – type of cell produced mitosis Characteristic Number of nuclear divisions Total Number of cells produced Number of chromosomes in cells (haploid or diploid) In a human cell there are 46 chromosomes. How many would be in a cell after…..