1. KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. (unicellular organisms divide to reproduce

2. The cell cycle represents the life cycle of a cell.
The cell cycle has three main stages:
(1) INTERPHASE
(a) G1: cell grows, organelles double in number; cell does its job
(b) S (DNA synthesis) DNA is copied
(c) G2 : More growth;
(2) Mitosis: division of the cell’s DNA
(3) Cytokinesis (cell divides into 2 cells)

3. Why do cells divide? They become too large
The volume of the cell increases faster than the surface area
Cells need large surface area (cell membranes) to move things in and out

4. 2. To make more cells so the organism can grow
Why do cells divide?
2. To make more cells so the organism can grow
Example: a growing baby needs more skin cells!
3. To replace old, worn out cells
Cells reproduce at different times depending on their jobs.

5. Some cells do not divide in adults:
Brain cells
Nerve cells
Muscle cells
Stem Cells are the focus of much research to find ways to create new cells of these types. Stem cells are cells that can produce or become any type of cell.

6. This is called the diploid number & is abbreviated 2n
KEY CONCEPT The goal of mitosis/cytokinesis is to make 2 identical daughter cells.
The number of chromosomes in a mitotic cell is double the number in a sperm or egg cell
This is called the diploid number & is abbreviated 2n
One mitotic 2n mother cell produces 2 identical daughter cells which are also diploid or 2n

7. The product…
Mitosis is a form of asexual reproduction that makes identical body cells
It results in two 2n daughter cells that are genetically identical to each other

8. KEY CONCEPT To remain healthy, mitosis must be controlled.

9. Apoptosis is programmed cell death.
It’s normal for healthy cells
cell produces self-destructive enzymes
Example:
Webbing between
Fingers in fetus
webbed fingers

10. In cancer, mitosis is uncontrolled.
Cancer cells divide constantly and form clumps called tumors.
Benign tumors: remain clumped; can be removed.
Malignant tumors: break apart (metastasize) and can form tumors in other parts of the body.
cancer cell
bloodstream
normal cell

11. Cancerous cells do not carry out normal functions.
Cancerous cells come from normal cells with damage to DNA.
Carcinogens are substances known to promote cancer.
Examples:
Standard cancer treatments typically kill both cancerous and healthy cells. (Radiation & chemotherapy)
People who have sunburns have an increased risk of cancer: Too much sun exposure can cause cancer due to radiation exposure from the sun which alters your DNA in a harmful way
UV light from the sun can alter DNA in a harmful way