1. The Cell Cycle

2. The Cell Cycle: Eukaryotes
The series of events that cells go through as they grow and divide.
During the cell cycle, a cell grows, prepares for division, and divides to form two identical daughter cells, each
of which then begins the cycle again.

4. Interphase: The longest phase of the cell cycle
G0 Phase:
Suspended rest period
The cell is not actively dividing
Includes nerve, heart and muscle cells
G1 Phase: (Gap-1)
Period of cell growth
New proteins & organelles
S Phase: (Synthesis)
Chromosomes are replicated
DNA synthesis
G2 Phase: (Gap -2)The Shortest of the 3 phases
organelles and molecules required for cell division are produced
Final Preparation for Mitosis

5. M Phase: Division of the cell Mitosis and Cytokinesis
Mitosis : Division of the nucleus
consists of 4 stages
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis:
*The division of the cytoplasm, occurs at the same time as telophase.

6. Cell Cycle Checkpoints
Cell cycle checkpoints verify whether the processes at each phase of the cell cycle have been accurately completed before continuing into the next phase

7. Cell Cycle Checkpoints

9. What are Chromosomes?
Carry the genetic information (traits) of the cell that are passed on from one generation of cells to the next.
Chromatids
A chromatid is basically one half of a chromosome
Prior to cell division, each replicates and consists of two identical sister chromatids.
When the cell divides, the chromatids separate from each other. One chromatid goes to each of the two new cells.
Each pair of chromatids is attached at an area called the centromere.

10. Chromosome Structure
Centromere
Sister Chromatids

11. The Cell Cycle
G0 Phase: rest
G1 checkpoint
M checkpoint
G2 checkpoint

12. Division of the Cell : All cells come from preexisting cells.
Why do cells divide?
Growth and Development
Repair (Healing)
Reproduction
( We will talk about this later in the year)

13. Division of the Cell : All cells come from preexisting cells.
Why do cells divide?
Growth and Development
Humans start off as one single cell, and by the time they are adults, they have over 10 trillion cells!!! This increase in the number of cells also allows for some of those cells to be specialized for various functions. This is important to the survival of many organisms.
A RESULT OF MITOSIS

14. Division of the Cell : All cells come from preexisting cells.
Why do cells divide?
Repair (Healing)
Some organism, are able to regenerate lost limbs (such as arms or tails). Humans can repair skin, blood vessels and bones, or replace cells that have died. You have a “new” skin every 28 days!
A RESULT OF MITOSIS

15. Division of the Cell : All cells come from preexisting cells.
How do cells divide?
PROKARYOTES
EUKARYOTES
Have only one circular chromosome
Divide by binary fission
Have a nucleus containing many chromosomes
Divide by Mitosis
VS.

16. Division of the Cell : All cells come from preexisting cells.
How do cells divide?
PROKARYOTES
EUKARYOTES
Binary fission in E. Coli
Mitosis in White Fish
VS.

17. Includes Mitosis as well as Cytokinesis
M Phase
Includes Mitosis as well as Cytokinesis

18. Mitosis Prophase Chromosome coil more tightly becoming visible
Centrioles move to poles of the cell
Nucleolus disappears
Nuclear envelope breaks down.

19. Mitosis Metaphase Chromosomes line up across the center of the cell.
The spindle connects the centromere of each chromosome to the two poles.

20. Mitosis Anaphase Chromosomes are separated
Spindle fibers shorten so chromosomes are pulled to poles of cell
Ends when the chromosomes stop moving.

21. Mitosis Telophase Chromosomes uncoil Nuclear membrane reappears
Mitosis is complete, Cell division is NOT.

22. Mitosis
Prophase
Metaphase
Anaphase
Telophase

23. Cytokinesis
At the end of mitosis, 2 nuclei are formed within the cytoplasm of a single cell. All that remains if the division of the cytoplasm.
This usually occurs at the same time as telophase.

24. VS. Cytokinesis Animals Plants
th cell membrane pinches in to form a cleavage furrow
Plants
A cell plate forms midway between the divided nuclei.
VS.