Mitosis

1. Mitosis

2. Title: Mitosis8th January 2014 Learning question: What are the names of the stages of mitosis? Homework: Complete exam questions by Wednesday15th January Hook: What connects these pictures? (Can you write more than one word?!)

3. Lesson Aims • (d) outline the processes taking place at the G1and G2points in the cycle; • (e) describe the appearance of the components of the nucleus and cell during mitosis with reference to: nuclear envelope, centrioles, spindle fibres, centromere, chromatids and chromosomes;

4. Key words… • Mitosis • Prophase • Metaphase • Anaphase • Telophase • Microtubules • Cytokinesis • Chromatid • Chromasome • Centromere • Centriole • Diploid

5. Cell division • All complex organisms originated from a single fertilised egg. • Every cell in your body started here, through cell division the numbers are increased. • Cells then specialise and change into their various roles

7. Mitosis • Mitosis is the process by which new body cell are produced for: • Growth • Replacing damaged or old cells. This is a complex process requiring is to be split into different stages to understand it.

8. DNA • ‘Blueprint of life’ • Codes for all the proteins needed for life • Describes that characteristics of every living thing • Every cell with a nucleus contains ALL the instructions to make the organism • http://www.pbs.org/wgbh/nova/photo51/media/journey.swf

9. Chromosomes • Each DNA strand is split into chromosomes • All sexually reproducing animals have pairs of chromosomes. One set of each pair comes from each parent • Humans have 23 pairs • Lions have 19 pairs • African wild dogs have 39 pairs • Mosquito have 3 pairs • Some ferns have 500-600 pairs

10. This (imaginary, example) animal has just two pairs of chromosomesRed = Maternal Blue = Paternal 1p 1m 2p 2m

11. During Interphase, each chromosome replicates and produces an exact copy of itself: 1p + copy 1m + copy 2p + copy 2m +copy

12. There are four stages to Mitosis • Prophase • Metaphase • Anaphase • Telophase • Remember though that this is a continuous process P M A T

13. Interphase • Standard condition of cell • DNA replicates • Cell enters reproductive cycle with 2 copies of each chromosome

14. Prophase • DNA super coils and chromosomes become visible • Nuclear membrane breaks down • Centrioles migrate to poles

15. Metaphase • Chromosomes line up centromeres on equator of cell • Centrioles form spindles

16. Anaphase • Spindles ‘grip’ centromeres and chromosomes migrate to poles

17. Telophase • Nuclear membranes reform • Chromosomes disperse • Cytokinesis begins

18. Interphase • Both daughter cells are exact copies of the parent cell

19. INTERPHASE MITOSIS

20. Stages of Mitosis • http://www.cellsalive.com/mitosis.htm

21. In humans, each cell (except sex cells) has how many chromosomes? ______ • After mitosis, how many daughter cells are produced?  _______.  After mitosis (in a human cell), each daughter cell has how many chromosomes? _____ • How many phases are in MITOSIS? ___________ • Which phase of the cell cycle is the longest?  _________ • During which phase does cytokinesis begin?  __________ • What cell parts migrate to the poles during prophase? __________________. • What structure holds the two chromatids together? ____________________ • During which phase does the nuclear membrane dissolve? __________________ • What structure moves the chromosomes into position and then pulls them apart? ___________________ • What is the overall purpose of mitosis? _________________________ • Complete textbook Q1-3

22. Welcome back • Which stage?

23. Lesson Aims • (d) outline the processes taking place at the G1 and G2points in the cycle; • (e) describe the appearance of the components of the nucleus and cell during mitosis with reference to: nuclear envelope, centrioles, spindle fibres, centromere, chromatids and chromosomes;