1. The Cell Cycle and Cell Division
Chapter 3 Lesson 1
The Cell Cycle and Cell Division

2. The Cell Cycle
Cell Cycle- most cells in an organism go through a cycle of growth, development, and cell division.
Organisms Grow
Organisms Develop
Organisms Replace Old and Damaged Cells
Organisms Produce New Cells

3. Phases of the Cell Cycle
Two Main phases
Interphase
A cell spends most of its life in interphase
Rapid growth and replication ( copying) of its membrane bound organelles
Copying DNA
Preparation for cell division
Mitotic Phase

4. Mitotic Phase A Cell reproduces at this time It has two phases
Nucleus divides in the first stage
Cell’s cytoplasm divides in the second stage
End product of mitosis is two identical daughter cells

5. Length of the cell cycle
Depends on the type of cell dividing
Eukaryotic cells have many membrane- bound organelles
Some cells it may last 8 minutes
Some cells it may take as long as a year
Most human cells take 24 hours

6. Interphase The cell rapidly grows
Increase in cellular activities like making proteins
Actively dividing cells make copies of their DNA
The DNA is called chromatin
It resembles spaghetti because it is long strands of chromatin are tangled together

7. Interphase cont.
G1 stage- Period of rapid growth, longest period of interphase
S stage- continues to grow, it also copies its DNA
G2- final period before the cell divides, also a period of growth
Each organelle is also replicated or copied

8. Mitosis The nucleus and the cells contents (organelles) divide
Divided into 4 stages
Prophase
Metaphase
Anaphase
Telophase

9. Prophase The copied chromatin coils together
Chromosomes begin to appear
Nucleolus disappears
The nuclear membrane dissolves
The spindle fibers begin to form

10. Metaphase The chromosomes line up in the middle of the cell
The spindle fibers attach to the centrioles and the centromeres
Shortest phase of mitosis

11. Anaphase The two sister chromatids in the chromosomes separate
The spindle fibers pull them apart in opposite directions
The cell begins to lengthen ( become longer or more oval in shape)

12. Telophase The spindle fibers begin to disappear
Chromosomes begin to uncoil
Nuclear membrane forms around each set of chromosomes forming a new nucleus
Spindle fibers begin to disappear

13. Cytokinesis Animal Cell Cells cytoplasm divides In animal cell
Cell membrane contracts around the middle of the cell
A furrow forms
The furrow gets deeper until the cell membrane comes together to divide the cell
In plant cell
A new cell wall forms in the middle of the plant cell
A cell plate forms and grows outward until a new cell wall is formed.
Plant cell

14. Results of cell division
Two identical daughter cells are formed
Reasons for cell division
Reproduction- some unicellular organisms reproduce this way
Growth- growth of an organism is dependent on mitosis
Replacement- cells in the skin are constantly being replaced
Repair- when a bone breaks or you cut your skin