1. Cell Division : Mitosis

2. Cell Division
essential to the production of new cells for the purpose of growth, tissue repair and sexual reproduction

3. Interphase Cells spend most of time performing valuable functions
This period when they are not dividing is called Interphase

4. DNA Replication Before dividing-DNA replication
- Duplication of DNA in nucleus
- DNA double helix unwinds, splits
into two strands (like a zipper)

6. Cell division:
- DNA strands coil & condense
- Form rod-like structure called
Chromosomes
- shaped like an “X”
- 2 rods (chromatid) joined
at centre
(rods exact copy of the other)
- Chromosomes form pairs (one with genetic info. From Mother, the other from Father)

7. # of chromosomes different in each species
Human contain “2n” where n represents number of pairs
Humans : n=23, so we have
23 pairs of chromosomes
so 2n=46 total chromosomes
other creatures:
Dogs : 2n=78, Cats: 2n=38
Fruit Fly: 2n= 8

8. Human Genome Contains 23 pairs of chromosomes
First 22 homologous (same size)
- 23rd pair -sex chromosomes (determines gender)
Ex. Males XY, Females XX

9. Human Genome (Karyotype)

10. Two types of cell division:
Mitosis: the process of cell division in which cells multiply in order to ensure growth and tissue repair.
- increases number of cells & replaces dead or worn cells
- Parent cell (original cell) divides producing 2 identical daughter cells
- forms diploid cells (2n: two sets of chromosomes)
- Somatic cells:cells that form tissues(not gametes)

11. All Diploid cells are somatic (form tissues in body)
- Consists of 4 phases:
Prophase
Metaphase
Anaphase
Telophase
(see p.134)

12. Diploid (2n)
Diploid (2n)