1. UNIT 7: Cell Division BIG IDEA: Cell division is the process in the body to create more cells and gametes

2. MITOSIS

3. Asexual Reproduction  Reproduction with only one parent  offspring are identical to parents

4. Sexual Reproduction  Requires 2 parents  New individual is produced by the union of the nuclei of two specialized cells (sperm & egg)

5. Chromosome Structure  Inside your nucleus are 3 billion nucleotides of DNA  In order to fit it is coiled and packed into a complicated but organized structure

6. Chromosome Structure  Histones- Proteins that DNA are wrapped around

7. Chromosome Structure  Chromatin- Less tightly coiled DNA wrapped around a histone Chromatid Chromosome

8. Chromosomes  Rod shaped structures made up of DNA and histones  Two identical halves are called chromatids  Point holding together the chromatids is called a centromere

9. Chromosomes  Structure in cells that undergo division and that contain hereditary information of the organism  In mitosis the chromosomes that undergo cellular division are called autosomes

10. Chromosomes  Draw a chromosome and label the centromere and the chromatids centromere chromatid

12. How many chromosomes are present in an autosomal cell?  23 pairs or 46 chromosomes  Refers to DIPLOID: meaning that a cell possesses 2 complete sets of chromosomes

13. Why are there two sets of chromosomes? –1 set is from your mother and 1 set is from your father –This leads to genetic variation because genetic information on chromosomes from your parents can be different  Example: both chromosomes can code for eye color except one can be for blue eyes and one for green eyes

14. Blonde Hair Black Hair Genetic Variation

15. Why is genetic variation beneficial?  Causes a diverse collection of genes  Increase in survival

16. CELL CYCLE  Cycle that a cell goes through in order to make new cells  If an organism is unicelluar, than a new organism is created via the cell cycle

17. Cell Cycle Consists of Two Parts:  Mitosis: –Division of the nucleus to form two identical nuclei –REMEMBER: Hereditary material is found in the nucleus  Cytokinesis –Division of the cytoplasm of the cell after mitosis

18. INTERPHASE

19. Interphase  Stage when a cell is between mitotic cycles: A. G1- cell grows B. S- DNA replication C. G2- Organelle replication

20. MITOSIS

21. Prophase  Chromosome become visible  Centrioles move to opposite poles of the cells  Microtubules form spindles  Spindle fibers become attached to centromeres  Nuclear membrane disappears  Nucleolus disappears

22. Prophase:

23. Metaphase  Chromosomes attach to the microtubule spindles  Chromosomes line up on the equator of the cell

24. Anaphase  Centromeres double  Chromosomes(si ster chromatids) move to opposite poles  Division (cleavage furrow) appears

25. Telophase  Begins when chromosomes reach the poles  Chromosome uncoil and become invisible  Spindle disappears  Nuclear membrane forms  Nucleioli reappears

26. Telophase

27. Cytokinesis in Animal Cells  Begins during late anaphase  Cytoplasm is pinched off by cell membrane

28. Mitosis & Cytokinesis in Plant Cells  Main events are the same  Plants do not have centrioles or asters  Cytokinesis cannot occur by pinching off of membrane a cell plate forms between the new cells during anaphase or telophase

29. Cytokinesis End with two identical daughter cells

30. Cells that divide rapidly  Plants  Animals

31. Cells that seldom or never divide  Xylem (part of a plant)  Nerve Cells  Muscle Cells