1. The Process of Cell Division
Section 10.2

2. What happens when you are done growing?
Does cell division STOP?

3. Chromosomes
Chromosome = Genetic information bundled into packages of DNA
Cells must package large molecules very carefully. They are able to do this because of chromosomes
Even small cells like E-Coli have A LOT of DNA
Total amount of DNA = 1.6mm
1,000 times longer than the cell!
Chromosomes have an important role in cell division
They must make a complete copy of their genetic information before cell division begins

4. Prokaryotic Chromosomes
No nucleus
Their DNA is found in the cytoplasm
Most prokaryotes contain a single, circular DNA chromosome that contains all of the cell’s genetic information

5. Eukaryotic Chromosomes
Eukaryotic cells generally have a lot more DNA than prokaryotes and will contain multiple chromosomes.
The number of chromosomes depends on the organism.
Fruit flies = 8 chromosomes per cell
Human cells = 46 chromosomes per cell
Carrot cells = 18 chromosomes per cell
Dog cells = 78 chromosomes per cell

6. Chromosomes form a close association with histones
Histones = type of protein
Chromatin = DNA tightly coiled around histones
DNA tightly coils around the histones and together they form a beadlike structure called nucleosomes

7. The Cell Cycle Prokaryotic Cell Cycle
Cells go through a series of events known as the cell cycle
During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells
Prokaryotic Cell Cycle
Asexual reproduction also known as binary fission
Results in the production of 2 genetically identical daughter cells

8. Eukaryotic Cell Cycle Consists of 4 phases
G1 S G M
Interphase – period in the cell cycle between cell division
G S G2
G1phase = cell growth
S phase = DNA replication
G2 = preparing for cell division
M phase = cell division
2 main stages: 1. mitosis 2. cytokinesis

9. Mitosis Mitosis – the division of the cell nucleus Four phases
Prophase
Metaphase
Anaphase
Telophase
Depending on the cell mitosis can last a few minutes to several days

10. Prophase The first phase of mitosis Usually the longest phase
What happens during prophase?
Chromatin condense into chromosomes
The centrioles move to opposite ends of the pole and begin to make spindle fibers
The nuclear membrane and nuclear envelope break down

11. Metaphase Second phase in mitosis Generally the shortest phase
What happens during metaphase?
Chromosomes line up in the middle of the cell
Chromosomes are connected to spindle fibers at the centromere

12. Anaphase 3rd phase of mitosis What happens during anaphase?
Chromosomes separate and pulled to opposite ends of the cell by the spindle fibers

13. Telophase The fourth phase of mitosis What happens during telophase?
Spindle fibers begin to break apart
The nuclear envelope begins to form around each set of chromosomes

14. Cytokinesis Cytokinesis = division of the cytoplasm
The cytoplasm pinches in half
Each daughter cell has an identical set of chromosomes