1. POD Compare and contrast asexual and sexual reproduction.
What do you think triggers cells to divide?
Give reasoning for your predictions

2. The structure of eukaryotic chromosomes

3. The Relationship between Chromosomes, DNA and Genes
DNA – deoxyribose nucleic acid
macromolecule, carries genetic information
A gene is a short section of DNA

4. DNA is tightly packed in the nucleus of every cell.
DNA wraps around special proteins called histones
which form loops of DNA called nucleosomes.
These nucleosomes coil and stack together to form fibers called chromatin.
Chromatin in turn forms larger loops and coils to form chromosomes.

5. TERMS YOU NEED TO KNOW:

6. Structure of a Chromosome

7. Chromosome Numbers Sex chromosomes - determine the sex of an organism
Autosomes - All other chromosomes in an organism

8. Somatic Cells (body cells) –
- 2 Sex chromosomes X or Y
- all other chromosomes are autosomes
Gametes (Sex cells)
- half the number of chromosomes as a somatic cell
- 1 sex chromosome

9. Example: Humans Somatic cells have 46 chromosomes Gametes
2 sex chromosomes
women have two X chromosomes
men have an X and a Y
44 autosomes
Gametes
1 sex chromosome
22 autosomes

10. Chromosome Numbers
Haploid and diploid are terms referring to the number of sets of chromosomes in a cell.
diploid cells (2n) - Somatic cells (body cells), contains two complete sets of chromosomes
every organism has a characteristic diploid number
haploid cells (n) - Gametes (sex cells) have only one complete set of chromosomes
the length and number of chromosomes is unique to each species of organism.

11. Chromosome Number 18 32 48 78 36 94
Organism
Carrot
Cat
Chimpanzee
Dog
Earthworm
Goldfish
Lettuce

12. Mactching sets of chromosomes in a diploid cell are
called homologous chromosomes. Both chromo in a
homologous pair contain information that code the
same trait (genes).
Example of trait: Eye color
Are sex chromosomes homologous? Why or Why not?

15. Cell Division and Reproduction
PBS : How Cells divide

16. Prokaryotic chromosomes
Lack true nuclei
DNA found in cytoplasm
Most contain a single, circular DNA chromosome

17. The Prokaryotic Cell Cycle Cell Division in Prokaryotes/Asexual Reproduction
BINARY FISSION is the division of a prokaryotic cell into 2 offspring cells. (asexual reproduction)
The cell grows in size.
DNA replication - The chromosome makes a copy of itself, resulting in two identical chromosomes
Cytokinesis - The cell splits into two new cells.  Each new cell contains identical genetic information as the original cell

19. A protozoan undergoes binary fission

20. Eukaryotic Cell Cycle The stages of life of a cell
Interphase
Mitosis
Cytokinesis

21. Eukaryotic Cell Cycle

22. Cell Division in Eukaryotes
A cell typically goes through stages during its life, growing and developing before it divides into new cells.
The cell cycle is the repeating events that make up the life of a cell

23. Interphase Period of normal metabolic activity
Carries on all usual functions
Increases in size
Synthesizes new proteins and organelles
DNA Replication – DNA is duplicated (copied)
Reminder: DNA exist as chromatin within the nucleus. Chromatin are thin uncoiled strands of DNA wrapped around a protein
allows each new cell will have a complete copy of each chromosomes

24. The actual dividing of the cell consists of two steps:
Mitosis
cytokinesis

25. Mitosis The division of the Nucleus
Process by which a nucleus divides into 2 identical nuclei
Mitosis produces two daughter cells that are identical to the parent cell.  If the parent cell is haploid (N), then the daughter cells will be haploid.   If the parent cell is diploid, the daughter cells will also be diploid. 
N ® N
2N ® 2N
This type of cell division allows multicellular organisms to grow and repair damaged tissue.

26. 4 phases of Mitosis

27. Prophase the chromatin coils (condenses) to form visible chromosomes*
nucleolus and the nuclear membrane begin to disappear
centrosomes (centrioles) appear
Spindle fibers start to form
Centrioles begin to move to opposite ends

28. The constricted area of each chromatid is called a centromere
The chromatin condensed into chromosomes
each chromosome contains two identical halves called sister chromatids
The constricted area of each chromatid is called a centromere
Centromere
Sister chromatids

29. Metaphase
chromosomes are moved to the center of the cell (equator) by the spindle fibers attached to the centromeres
The two sister chromatids of each chromosome are attached to spindle fibers from opposite ends of the cell

30. Anaphase
The sister chromatids are separated from each other; now considered to be individual chromosomes
The centromeres of each chromosome are pulled by the spindle fibers toward the opposite ends (poles) of the cell

31. Telophase
after the chromosomes reach opposite ends of the cell, the spindle fibers breakdown
the chromosomes return to less tightly coiled Chromatin
new nuclear envelope begins to form around the chromosomes at each end of the cell
End of mitosis
Nuclear envlopes reappear

32. Cytokinesis
The cell membrane begins to pinch the cell in two as cytokinesis begins
the cytoplasm of a cell and its organelles are equally separated into two daughter cells
Completes the process of cell division
the new cells are now in interphase

33. Cytokinesis differs between plants and animals
Plant cells have a rigid cell wall, so the plasma membrane does not pinch in.
the material for the new cell wall is called the cell plate
The cell plate and membranes gather and fuse along the equator, between two two nuclei forming two identical cells

34. Results: unicellular organisms remain as single cells
in multicellular organisms, cell growth and reproduction result in groups of cells that work together as tissue to perform a specific function

35. Normal Control of the Cell Cycle
Proteins regulate the progress of cell division
Occasionally, cells lose control of the cell cycle.
uncontrolled dividing of cells can result from proteins not functioning properly
cancer is a malignant growth resulting from uncontrolled cell division