1. Cell Division and Mitosis
Chapter 6

2. Chromosome Chromosomes are tightly coiled DNA and protein
Chromatin is a mass of DNA and protein
Chromatin coil up to form Chromosomes during the early stages of cell division
The human chromosome contains about ½ billion nucleotides

3. Structure of the Chromosome
Has 2 identical strands called sister chromatids that are connected to the centromere.
Before cell division, chromosomes replicate to make the sister chromatid.
The shape of the chromosome is a double helix.

4. Chromosome number
In humans there are:
46 in normal cell
23 in sex cells
The set of chromosomes for an organism is called a karyotype
Diploid - 2 sets of chromosomes (pair), one from each parent
Haploid - 1 chromosome

5. Diploid
Haploid 23 8 66 46 4 33

6. Sex Chromosomes
Sex chromosomes determine whether you are male or female
X and Y
In humans: XX is female and XY is male.
the female egg can only contain a X chromosome.
the male sperm contains either a X or Y chromosome. The male determines the sex of the child
In birds, moths, and butterflies: XX is male and XY is female.

7. The Cell Cycle
Cell Cycle is a cycle of growth and division

8. Three major parts of cell cycle
Interphase
Mitosis – nucleus division
Cytokinesis - cell division
For all eukaryote cells the stages are the same, but the length of time the stages last varies.

10. Interphase Cells carry out the tasks of life. DNA duplicates G1 phase
Organelles duplicate
3 stages of Interphase
G1 phase
Intense growth
Cells spend most of their life in this stage

11. DNA duplicates to create sister chromatids
S phase
DNA duplicates to create sister chromatids
G2 phase
Growth
Organelles duplicate
Cell prepares for division

13. Mitosis
4 stages
Prophase
Metaphase
Anaphase
Telophase

14. Cytokinesis Cellular division
Cell divides in half and becomes 2 identical daughter cells

15. Controlling the cell cycle
The cell cycle is controlled by proteins called cyclins.
Cancer is the uncontrolled growth and division of cells. A clump of cells is called a tumor
Factors that may cause cancer:
Mutation in genes
Radiation
Cigarette smoke
Diet and obesity

17. Cell Division Cell division in Prokaryote cells (bacteria)
Bacteria grows
Circular DNA copies itself and attaches to the cell membrane
Cell pinches inward and splits
This is called binary fission

19. Mitosis 4 distinct phases
Process in which the nucleus divides to form two identical nuclei
Occurs after interphase
4 distinct phases
“PMAT” to help
remember
4 steps of Mitosis

20. Prophase Chromatin finish condensing and coil up to form chromosome.
Nuclear membrane disappears
Spindle fibers begin to stretch across the cell

21. metaphase chromosomes attach to spindle fibers at the centromere.
Chromosomes line up in the middle of the cell.

22. Anaphase Chromatids separate. Spindle fibers start to break down.
Chromatids are pulled the opposite sides by the spindle fibers.
Spindle fibers start to break down.

23. Telophase Nuclear membrane reappears around each set of chromosomes.
Chromosomes uncoil and form chromatin.
Spindle fibers disappear.

24. Cytokinesis Cytoplasm is pinched in half and separates.
Forms two identical daughter cells.

25. Results of Mitosis
1. Each cell in your body (except sex cells) has the same number of chromosomes- 46

26. Results of Mitosis
Allows for growth and replaces worn out or damaged cells

27. D. Asexual Reproduction
A new organism is produced from one parent organism
3 types
Fission
Budding
Regeneration

28. D. Asexual Reproduction
1. Fission- An organism with no nucleus divides into two identical organisms by fission
Example: bacteria

29. D. Asexual Reproduction
2. Budding- A small exact copy of the adult grows from the body of the parent
Example: hydra

30. D. Asexual Reproduction
3. Regeneration, a whole new organism grows from a piece of the parent
Example: sea star