1. What you’ll learn about in this unit:  Why and how cells divide  The three types of cell division: Binary Fission, Mitosis and Meiosis Binary Fission, Mitosis and Meiosis  What regulates or controls when cells start and stop dividing.  How cells specialize during their life  Mistakes that occur during division that can lead to cancer and genetic disorders

2. Unit 5 Cell Division Key Concept: All cells come from preexisting cells – Cell Theory

3. Cell division – process by which cells produce new cells

4. Purpose of Cell Reproduction /Division   Create new cells that contain the genetic material (DNA) stored in chromosomes.  

5. Purpose of Cell Division 1. 1. Binary Fission – Creates 2 genetically identical new organisms by asexual reproduction 2. Mitosis – Creates somatic / body cells Ex. Skin, nerve, blood Used for growth, to repair damage or replace worn out cells 3. Meiosis – Creates gametes / sex cells Used for sexual reproduction

6. Chromosomes When a new cell is made it must receive a copy of the genetic material from the parent cell. Chromosomes are made of the DNA (genetic info) and“carry” it from a parent cell to the daughter cells.

7. Chromosome Location in Cells   Eukaryotic cells – Nucleus   Prokaryotic cells– Cytoplasm (Nucleoid Region)

8. Chromosome Shape  Eukaryotic cells - Rod, Linear  Prokaryotic cells – Circular

9. Chromosome Structure  2 Types of Molecules joined together 1. DNA (nucleic acid) 1 in each chromosome 2. Histones (protein) 1000’s in each chromosome

11. Two Types of Chromosomes  Autosomes – carry genes not related to sex  Sex chromosomes – carry genes for sex traits XX – Female XY - Male

12. Homologous Chromosomes

13. Body Cells and Sex Cells have different numbers of chromsomes Somatic / Body Cells   Have 2 copies of each chromosome 1 from each parent – Diploid 2n   Members of a species have the same chromosome number in body cells Ex. Humans 46 Dogs 78 Fruit Flies 4   Made through Mitosis

14. Body Cells and Sex Cells have different numbers of chromsomes Gametes / Sex Cells   Have only 1 copy of each chromosome - Haploid 1n   Made through Meiosis

15. Haploid 1n Diploid 2n

16. 3 Major Types of Cell Division

17. Binary Fission * Used by Prokaryotes and some unicellular Protists * Makes two genetically identical daughter cells (clones)   Form of asexual reproduction

18. Mitosis   Used by eukaryotic organisms   Process of making somatic/ body cells   Ex Skin, nerve, muscle   Used for growth, to repair damage or replace worn out cells   2 Daughter cells are created from the division on one parent cell   Daughter cells are genetically identical to the parent cell –they “inherit” an exact copy of the same chromosomes

19. Mitotic Cell Division X= Number of chromosomes Parent Cell X Daughter Cells X X

20. Meiosis   Used by sexually reproducing eukaryotics.   Process of making gametes/ sex cells.   4 new cells are made from one parent cell.   New cells are NOT genetically identical to the parent cell.   Daughter cells have only half the number of chromosomes as the parent cell.   Also known as Reduction Division

21. Meiotic Cell Division X= Number of chromosomes Parent Cell Parent Cell X Daughter Cells Daughter Cells ½ X

22. Gametes are made in Meiosis

23.  DNA in threadlike form – Chromatin  DNA in coiled /condensed form - Chromosome

24. Chromosome number is different in sex cells and body cells Haploid (n) cells have only 1 copy of each type of chromosome - Sex cells are haploid Diploid (2n) cells have 2 copies of each type of chromosome. –Body cells are diploid.

25. The zygote (fertilized egg) doubles its chromosomes and divides millions of times resulting in growth. Each new cell receives a complete set of all the chromosomes

26. 6.1 Chromosomes and Meiosis Meiosis occurs in the testicles and ovaries. –Produces sex cells: egg and sperm. –Sex cells are what transport/carry the parents DNA to their kids body cells sex cells (sperm) sex cells (egg)

27. 6.1 Chromosomes and Meiosis Haploid (n) cells have one copy of every chromosome. –Gametes are haploid. –Gametes have 22 autosomes and 1 sex chromosome.

28. 6.1 Chromosomes and Meiosis Chromosome number must be maintained in animals. Many plants have more than two copies of each chromosome. Mitosis and meiosis are types of nuclear division that make different types of cells. Mitosis makes more diploid cells.

29. 6.1 Chromosomes and Meiosis Meiosis makes haploid cells from diploid cells. –Meiosis occurs in sex cells. –Meiosis produces gametes.

30. Cell Division Vocabulary  diploid (2N) – a cell with 2 chromosome sets in each of its cells; all body (somatic) cells  haploid (N) – a cell with 1 chromosome set in each of its cells; all gametes (sperm, eggs)