1. How does a baby grow into an adult? Newborn baby has between 1 and 5 trillion cells Grown adult has between 50 and 100 trillion cells

2. How does a wound heal?

3. DNA Replication and Cell Division

4. The importance of cells All tissues in our bodies are made up of cells Cells must be replicated: - to support growth (ex: baby to adult) - to replace damaged or dead cells (ex: healing a wound or mending broken bones)

5. DNA – The instructions for life (Review – don’t copy) The cell’s nucleus contains the master set of instructions that determines: - what the cell will become & how it will function Instructions are carried in chromatin Chromatin: long, thread-like pieces of DNA, divided into segments called genes

6. DNA Replication Before a cell divides, DNA replication occurs The cell makes a copy of every chromatin strand Copies are called sister chromatids

7. DNA Replication Chromosomes: doubled chromatin strands wind up, shorten and thicken

8. Chromatin vs. Chromosomes November 16, 2016 sister chromatids identical strands centromere single- stranded chromatin double- stranded chromatin DNA replicates double- stranded chromosome centromere Mitosis DNA replication

9. Determine sex XX = female XY = male Humans have 23 pairs of chromatin in each cell All 23 pairs must be replicated before cell division can take place Determine all traits except sex

10. Two copies: sister chromatids Centromere holds sister chromatids together

11. Cell Division Once DNA replication is complete, cell division begins Two steps: 1) mitosis (4 phase process) 2) cytokinesis

12. 1. Mitosis A four phase process in which the duplicated contents of a cell divide into two parts. 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase

13. Your Task: a) Form groups of 4 students. b) Each member of the group is to become an expert on one phase of mitosis by reading the corresponding pages in your text (p. 34 – 35) and filling in the handout. c) Teach the other students in your group about the phase you studied and complete the handout together. d) If time permits: Take a set of images of mitosis from the front counter and try to put them in the correct order in your group.

14. Homework Read pages 37-38 (on cytokinesis) Mitosis Cut & Paste

15. Review http://iknow.net/player_window.html?url=m edia/prophase_video_auto.swf&width=360 &height=285http://iknow.net/player_window.html?url=m edia/prophase_video_auto.swf&width=360 &height=285

16. CELL CYCLE – PROPHASE 1.ProphaseStages of Mitosis November 16, 2016 centrioles spindle fibres double- stranded chromosomes  centrioles move to the opposite ends of the cell  spindle fibers form between centrioles  chromatin coils up into chromosomes  nuclear membrane & nucleolus disintegrate  chromosomes hook onto spindle fibers by their centromeres

17. CELL CYCLE – METAPHASE 2. MetaphaseStages of Mitosis November 16, 2016 centrioles spindle fibres sister chromatids  spindle fibres shorten or lengthen pulling chromosomes to align in the middle (equator) of the cell

18. CELL CYCLE – ANAPHASE 3.AnaphaseStages of Mitosis November 16, 2016 single-stranded chromosomes  centromeres split & each half pulls the chromatids to opposite ends  chromosomes are now single- stranded

19. CELL CYCLE – TELOPHASE 4.TelophaseStages of Mitosis November 16, 2016 cytokinesis 2 new identical nuclei  centrioles replicate  nucleoli & nuclear membrane reappear  chromosomes unwind into chromatin  cytokinesis begins  spindle fibres are disassembled

20. 2. Cytokinesis The division of the cell into two daughter cells Begins near the end of telophase

21. Cytokinesis in animal cells Ring of specialized proteins at middle of cell start to contract Pinches cell membrane until parent cell becomes two daughter cells Each daughter cell has cytoplasm, organelles & complete set of chromosomes in a nucleus

22. Contraction of proteins and pinching of membrane Two daughter cells produced

23. Cytokinesis in plant cells Golgi body produces small vesicles that carry materials to make new cell wall Vesicles line up at centre of cell forming cell plate Cell plate grows out to meet old cell wall  new wall formed separating two daughter cells

25. Comparing cytokinesis in animal and plant cells

26. Homework Stages of Cell Cycle Worksheet