1. Cell Growth and Division

2. Chromosomes
A gene is a segment of DNA that codes for RNA and protein; hereditary units.

3. Eukaryotic Chromosome
Chromatin – substance made of DNA and proteins.

4. Eukaryotic Chromosomes
Chromatid – one of the 2 strands of a chromosome that you see during meiosis & mitosis.
Centromere – Region that holds the two sister chromatids together during mitosis.

7. Chromosomes
Homologous chromosomes – Have the same sequence of genes, same structure, and pair during meiosis.
Crossing-over – exchange of genetic material between homologous chromosomes during meiosis

9. Cell Cycle

10. First three phases in the cell cycle are known as Interphase!
Cell Cycle Order
G1 (cell growth)
S (DNA synthesis)
G2 (growth and preparation for mitosis)
Mitosis
Cytokinesis
First three phases in the cell cycle are known as Interphase!

11. * Somatic cells = two copies of chromosomes for a total of 46*
Mitosis
Mitosis:
-Division of somatic (body) cells
* Somatic cells = two copies of chromosomes for a total of 46*

13. Mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

14. Interphase Interesting things happen! Cell preparing to divide
Genetic material doubles

15. Prophase Chromosomes pair up! 1. Chromosomes begin to condense
Centrioles move to the opposite sides of the nucleus and a spindle forms. (Help with mitosis)
Nuclear membrane disappear.

16. Metaphase Chromosomes meet in the middle!
Chromosomes arrange at middle of cell.
Attached to spindle fibers by centromeres.
Homologous chromosomes do not associate.

18. Anaphase Chromosomes get pulled apart
Spindle fibers shorten pulling chromatids apart.

19. Telophase Now there are two! Chromosomes uncoil
Spindle fibers disappear
Nuclear membrane forms
Cell divides

21. Cytokinesis Cell membrane grows in the middle.
Two “daughter” cells form.
Each cell has ½ of the parent’s cytoplasm and organelles.

23. What stage does each number represent?

24. Crazy Cell Growth Cell growth and division depend on protein signals.
Ex: When you cut yourself  skin cells divide rapidly
Cancer- group of diseases characterized by uncontrolled growth of abnormal cells

25. Mitosis and Meiosis

26. Meiosis Meiosis - division of gametes (sex cells)
4 daughter cells produced.
Each daughter cell has half the chromosomes of the parent.
2 sets of cell division involved.

27. Meiosis I Start with a diploid cell. Crossing over occurs.
Two cells formed

28. Meiosis II
Chromosomes divide
Four haploid cells formed

29. Haploid vs. Diploid Cells
Diploid – two sets of chromosomes (body cells)
Haploid – one set of unpaired chromosomes (gametes)
n = number of chromosomes
Haploid = 23 chromosomes
Diploid = 2n = 46 chromosomes

30. Asexual vs. Sexual Reproduction
Asexual reproduction – a parent passes a complete copy of its genetic information to each of its offspring; look the same!
Sexual reproduction – two parents give genetic material to produce offspring that are genetically different.
Males = XY
Females = XX