1. 10.2 The Process of Cell Division
Lesson Overview
10.2 The Process of Cell Division

2. Chromosomes
Chromosomes make it possible to separate DNA precisely during cell division.
The genetic information that is passed on from one generation of cells to the next is carried by chromosomes.
Every cell must copy its genetic information before cell division begins.
Each daughter cell gets its own copy of that genetic information.
Cells of every organism have a specific number of chromosomes.
mitosis

3. Prokaryotic Chromosomes
Prokaryotic cells lack nuclei. Instead, their DNA molecules are found in the cytoplasm.
Most prokaryotes contain a single, circular DNA molecule, or chromosome, that contains most of the cell’s genetic information.
DNA unzips making 2 strands and each strand is copied giving 2 identical copies of DNA.

4. Binary fission
Binary fission- Bacterial cell grows and then splits into equal halves.
Product of binary fission – 2 identical bacterial

5. Eukaryotic Chromosomes
In eukaryotic cells, chromosomes are located in the nucleus, and are made up of chromatin.
Chromatin is composed of DNA and histone proteins.

6. DNA coils around histone proteins to form nucleosomes
The nucleosomes interact with one another to form coils and supercoils that make up chromosomes.

7. The Eukaryotic Cell Cycle
Interphase consists of phases: G1, S, G2
Interphase is the time between cell divisions.
G1 – rapid cell growth, a cell is in this part
of the cell cycle for the longest period of time
between cell divisions.
S – DNA is copied, chromosome replicated
is now two sister chromatids joined at
centromere

8. G2 Phase: Preparing for Cell Division
G2 – Organelles replicate, microtubules are
reassembled to form spindle apparatus that
will move chromosomes, cell is now
prepared for mitosis.
This is the shortest phase of interphase.
An eukaryotic cell spends most of its time in
Interphase.

9. M Phase: Cell Division
In eukaryotes, cell division occurs in two stages: mitosis and cytokinesis.
Mitosis is the division of the cell nucleus.
Cytokinesis is the division of the cytoplasm.
After cytokinesis is complete, the cell will be in Interphase again.

10. MITOSIS Biologists divide the events of mitosis into four phases:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

11. PROPHASE
Chromosomes condense and become visible.
Centrioles form and take up positions on opposite ends of the nucleus.
Spindle becomes visible.
Nuclear membrane breaks down, and the nucleolus
disappears.

12. Metaphase
Spindle fibers (kinetochore) assist in moving the chromosomes to the equator (middle) of the cell.
The centromeres of all the sister chromatids line up.
The imaginary line that bisects each of
the chromatids through the centromere
is called the metaphase plate.

13. ANAPHASE Sister chromatids separate from each other at the centromere.
The spindle now pulls each chromosome to opposite ends of the cell (toward the centrioles).
The spindle is taken apart as the chromosomes move.
Each pole now has one complete set of chromosomes.

14. TELOPHASE
Chromosomes uncoil, spindle fibers disappear, and the nuclear membrane reforms.
Mitosis is complete.
Is the cell divided???

15. Cytokinesis
Cytokinesis is the division of the cytoplasm. Cytokinesis completes the process of cell division – it splits one cell into two.
Animal cells pinch in the membranes forming a cleavage furrow.

16. Cytokinesis in Plant Cells
In plants, the cell membrane is not flexible enough to draw inward because of the rigid cell wall.
Instead, a cell plate forms between the divided nuclei that develops into cell membranes.
The plate is formed from secretions of the golgi.
A cell wall then forms in between the two new membranes.

17. Important Cell Structures Involved in Mitosis
Chromatin- genetic material in a non-dividing cell, loose strands
Chromatid – each strand of a duplicated chromosome
Centromere – the area where each pair of chromatids is joined
Centrioles – tiny structures located in the cytoplasm of animal cells that help organize the spindle
Spindle – a fanlike microtubule structure that helps separate the chromatids

18. The Stages of the Cell Cycle mitosis review