Mr. Lopez's Biology Class: Chapter 5

5.1 The Cell Cycle

Cycle=repetition or repeating patterns.

G0 (Gap 0): cells carry out their normal functions but are unlikely to divide ex: Neurons

1. gap 1
2. cell growth, normal functions, replications of organelles, length of time a cells varies for each cell & organism. Critical check point in cell division #1 @ the end of G1.
3. synthesis.
4. copies DNA from the nucleus
5. gap 2
6. more growth and normal functions, Critical check point in cell division #2 @ the end of G2.
7. mitosis
8. cell division
9. prophase
10. metaphase
11. anaphase
12. telophase
13. cytokinesis Cyto=Cell Kinesis=division
14. mitosis
15. interphase

Cells divide at different rates:

Rates of cell division vary widely
Cell divides according to the body’s need (Ex. Skin cells divide more often then liver cells.)
The length of gap 1 varies widely among cell types.
Neurons, enter a stage called G0, where cells are unlikely to divide again.

Cell size is limited due to surface to volume ratio:

If cell is small it could not contain organelles and needed molecules.
If cells is large it could not move enough materials across the membrane surface.
To be at perfect size cell growth and division must be coordinated.

Experiment Explaining The Importance of Size of Cell

G1& G2 stages got their names because scientists did not see any activity going on in cells, and thought there were Gaps in cell activity.

M-Phase (Mitosis): the cell nucleus and its contents divide this includes cytokinesis.

What Breast Cancer Cells Look Like When Dividing

Section 2: Mitosis and Cytokinesis

Chromosome Structure

A chromosome is one long thread of DNA.

DNA wraps around proteins called histones.

Each Sister Chromatids join together forming a structure called Chromosomes.

Chromosomes condense at the start of mitosis so that they be ready to divided. They don't remain condensed all the time because genes must be easily accessible.

Telomeres and Aging

What organelles are involved in Mitosis?

Nucleus (chromosomes)
Centrioles (where the spindle fibers are produced)
Cell membrane

1. interphase: duplicates organelles, duplicates DNA, cell grows

2. prophase: chromosomes condense, nucleus breaks down, spindle fibers form (long threads used in cell division)

3. metaphase: spindle fibers align chromosomes along the middle of the cell

4. anaphase: chromatids separate to opposite sides of cell

5. telophase: nucleus membranes start to form around chromosomes & chromosomes begin to uncoil

6. cytokinesis: divides the cytoplasm between two daughter cells

Mitosis

Mitosis using your hands

But what happens in Plant Cells?

Lets Review

Download the app VINE for tomorrow....

Creating mitosis using VINE

You will create a vine on mitosis correctly placing the names with the process.
Be sure to allow enough time to show how Mitosis works.

Mitosis Vine Video
Mitosis Vine Labels

Section 5.3 Regulation of Cell Cycle

The regulation, or control, of the cell cycle is important for healthy cells to grow. Having uncontrollable division results in what we know as CANCER!

Take a look at this video....

Cancer Cells vs Normal Cells

How does cancer affect the body?

The cell uses Internal and External Factors

External Factors: The cell uses physical and chemical signals to control the cell cycle. When cells get around other cells they stop dividing.

Many cells release chemicals to neighboring cells to begin to divide.

Internal Factors: When external factors bind to cells they cause a response inside the cell. Enzymes and proteins, called kinase and cyclins, help the cell move through the cell cycle.

Apoptosis: Programmed cell death. When the cell is damaged or it is no longer useful it programs itself to die. This avoids any problem the cell might contain from spreading to neighboring cells.

take a look...

Apoptosis

Uncontrolled Cell Division

Benign tumors: relatively harmless because they clump together and can be removed

Malignant tumors: cancer cells that break away from the tumor and travel to other parts of the body.

Metastasize: Once the malignant tumors break away and travel through the blood stream they appear at other parts of the body

Metastasis

Carcinogens substances that are known to cause or lead to cancer

Is Red Meat Giving You Cancer

Benign Tumor?

Lets review

Section 5.4 Asexual Reproduction

Asexual reproduction is the production of offspring from a single parent. The offspring are, for the most part, genetically identical to each other and to the parent.

Usually seen in unicellular organisms (prokaryotes and some eukaryotes).

Multicellular organisms undergo a different type of asexual reproduction called known as mitosis, vegetative reproduction, and/or "budding". EX: Starfish, Hydra