1. Mitosis and DNA Replication

2. Cell Division
Occurs in humans and other organisms at different times in their life.
Cell Division differs depending on type of organism:
Eukaryotic organisms undergoing growth, development, repair, or asexual reproduction divide by mitosis.
EXAMPLE: new hair, nails, skin, liver, cells, etc… are produced.

3. Interphase
95% of cell cycle in interphase
Cells replicate their DNA

4. Mitosis
Mechanism used by cells to replicate DNA and produce identical cell copies.
5% of cell cycle is mitosis
Happens in all cells

5. Mitosis It is broken down into 5 major stages: Prophase Metaphase
Anaphase
Telophase

6. Prophase 1st phase of Mitosis
Nucleolus breaks down & Nuclear membrane disappears
Chromosomes condense –sister chromatids stay attached by the centromere
Kinetochore fibers form

7. Metaphase 2nd phase of Mitosis
The kinetochore fibers move the Chromosomes to the equator (middle)
Each chromatid is attached to the fibers at the centromere.

8. Anaphase 3rd phase of Mitosis Centromeres split
Sister chromatids are pulled apart to opposite poles of the cell
After chromatids separate, they are considered to be individual chromosomes.

9. Telophase 4th phase of Mitosis
Chromosomes begin to uncoil back into chromatin state.
Cytokinesis
Cytoplasm divides
Two new daughter cells are now separate
2 nuclear membranes form around each set of chromosomes.
Nucleolus forms in
each of the newly
formed cells.

10. Mitosis Animation

11. Deoxyribose Nucleic Acid
DNA
double-stranded
sugar = deoxyribose
bases = A,T,C,G

12. Free Nucleotide

13. DNA Replication

14. DNA Replication
DNA copies itself exactly
(Occurs within the nucleus)
Any mistake in copying = mutation

15. Basic Facts of DNA Replication
Complementary base pairing
makes replication possible
C - G
A - T

16. Basic Facts of DNA Replication
One side of DNA molecule is a
template for making the other side (strand)

17. DNA Replication Step 1: Uncoil & unzip DNA molecule
This occurs because of a weak hydrogen bond between the bases.

18. DNA Replication
Step 2:
Enzyme brings in complementary N-bases

19. DNA Replication Each new DNA molecule contains one old strand &
one new strand

20. DNA Replication Animation