1. Mitosis: When Cells Divide

2. Introduction to Mitosis
Define the following:
1. Chromosome: 9. Draw the phases of
2. Chromatid: mitosis (p.247)
3. Centromere:
4. Prophase:
5. Metaphase:
6. Anaphase:
7. Telophase
8. Diploid number

3. Mitosis
Mitosis: the division of a cell’s nucleus that leads to the formation of two identical cells

4. Chromatin to Chromosomes
Chromatin: long, threadlike strands of DNA (genetic material)
Chromosome: condensed DNA that is formed during mitosis
DNA wraps around proteins to form chromosome
Genes that control traits are located on these chromosomes

5. The Human Genome (Karyotype)

6. Chromosomes Before mitosis, DNA replicates
Chromosomes are then composed of two similar halves, called chromatids
When two chromatids are together they are called sister chromatids (aka homologous chromosomes)
Attached at the centromere
Chromatids
Centromere

7. Chromosomes Sister Chromatids each come from a parent (Mom or Dad)
They are the same (homologous)
Sister Chromatids
Centromere
One
chromatid
(dark blue)
Parent A
One
chromatid
(light blue)
Parent B

8. Chromosomes – Questions
Human genetic material is organized into _______________.
Label A and B.
Half of each
chromosome comes
from ______ and half
from ______.

9. Where Does Mitosis Occur?
Somatic (body) cell: any cell of the body that is not sperm or egg
Mitosis occurs here
Body cells are diploid: having two sets of each chromosome
Diploid number in humans is 46
Mitosis creates EXACT copies of itself
Original cell DIPLOID creates two identical cells both DIPLOID

10. Where Does Mitosis NOT Occur?
Gametes (sex cells): egg, sperm, pollen ovule of flower, spores
Gametes are haploid: having only one set (half) of each chromosome
Haploid number is humans is 23

11. Haploid or Diploid? Haploid or Diploid? How many sets of chromosomes?

12. Cell Types and Division – Questions
Division of the nucleus of body cells is ________.
There are two types of cells in the human bodies: body cells and _________.
Cells that undergo cell division are ______________ to each other.

13. Interphase The cells prepares to divide in INTERPHASE
Interphase occurs BEFORE mitosis
G1: cell growth
S: DNA replicates
G2: duplication of organelles, prepare for mitosis

14. Mitosis Prophase- Metaphase- DNA condenses into chromosomes
Nuclear envelope disappears
Metaphase-
Chromosomes line up in the middle

15. Mitosis Anaphase- Telophase- Cytokinesis- sister chromosomes separate
nuclei divide, nuclear envelope reforms
Cytokinesis-
cells separate

16. How to remember the phases of mitosis
In order – PMAT
Prophase
Metaphase
Anaphase
Telophase

18. Interphase Cells in normal living processes
Cell Grows and replicates DNA and organelles
Replicates centrioles

19. Prophase Chromatin condenses into chromosomes Centrioles separate
Spindle apparatus begins to form
Nuclear envelope disappears

20. Metaphase Chromosomes line up (at the metaphase plate)
Spindle fiber connects to chromosome at centromere
Centrosome
Centromere
Metaphase
plate
Sister
chromatids
Polar
microtubules

21. Sister chromatids separate
Anaphase
Sister chromatids separate
Individual chromatids are moved apart

22. Telophase and Cytokinesis
chromosomes gather at opposite ends of the cell
Chromosomes lose shape
New nuclear envelope forms
Cytokinesis:
Cytoplasm pinches into 2 daughter cells
Each daughter cell has identical duplicate chromosomes

24. Discussion Questions What are the four phases of the cell cycle?
How are cytokinesis, and telophase different?
What is important about metaphase?
Where are genes found?
What is the difference between a chromatid and a homologous chromosome?
Cancer cells undergoing mitosis in 6 hours
Mitosis 1 3D
Mitosis 2