Why do cells divide?

Agenda for Friday Dec 19th 1. Go over test2. Mitosis notes & video3. Mitosis worksheet

Grades on wall

Why does a cell divide?• Too large to work efficiently

– Smaller the cell = quicker it can work• Transport of Substances• Cellular communication

– Ratio of surface area to volume

Other reasons for cellular division• Growth

• Replace damaged cells

The Cell Cycle

• Cell reaches max size it stops growing or divides– Cells reproduce by growing and dividing = cell cycle

• 3 main stages of cell cycle1. Interphase – cell grows, replicates DNA2. Mitosis – nucleus and nuclear material divide3. Cytokinesis – cytoplasm divides

3 Stages of InterphaseGap 1 (G1)• Right after cell divides, normal functions,

prepares to replicate DNASynthesis (S)• Cell copies DNA (contains genetic material)

– Chromatin is the relaxed form of DNA– Chromosomes are the condensed form of DNA

Gap 2 (G2)• Cell prepares for mitosis

Mitosis• Cell’s DNA separates

– Creates 2 identical daughter cells– Same DNA– Same Number of Chromosomes in each cell

• 4 Stages – Prophase, Metaphase, Anaphase, Telophase

1. Prophase• Chromatin condenses into chromosomes

– X – shaped– Consist of two chromatids – identical copies of DNA– Chromatids are connected at a centromere

1. Prophase

• Nuclear membrane disappears • Spindle apparatus appears

– Spindle fibers, centrioles, and aster fibers– Helps move chromosomes

2. Metaphase• Chromatids Line up at center of cell

3. Anaphase• Chromatids pull apart

4. Telophase

• Chromosomes arrive at the poles• Chromosomes unwind (back to chromatin)• Two nuclear membranes begin to form• Spindle apparatus disappears

Cytokinesis

• Divides cytoplasm

• Animal Cells– Microfilaments constrict/pinch the cytoplasm

• Plant Cells– Cell plate forms between two daughter nuclei – Cell walls then form on either side of cell plate

Explain what happens in each step of mitosis.

Agenda for Monday Jan. 5th 1. Review mitosis (video)2. Go over HW3. Mitosis Cell Lab

• https://www.youtube.com/watch?v=L0k-enzoeOM

If a cell has 150 chromosomes how many daughter cells are created at the

end of mitosis? How many chromosomes are in each cell?

Agenda for Tuesday Jan 6th 1. Finish mitosis onion cell lab

http://www.sumanasinc.com/webcontent/animations/content/mitosis.html

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

What is cancer?

Agenda for Thursday Jan 8th 1. Cancer Notes2. Cancer worksheet

Cancer Vocab• Cancer – uncontrolled growth and spread of

abnormal cells• Neoplasm – new growth of tissue that serves

no physiological function• Tumor – clumping of neoplasmic cells• Malignant - cancerous• Benign - noncancerous• Biopsy –examination of cell development

Skin Cancer• The ABCD’s of melanoma (skin cancer):

– Asymmetry: one half is not like the other– Border: the edges are jagged or irregular– Color: the color is varied, tan, red, black ect– Diameter: the diameter is larger than 8mm

(the top of a pencil eraser

A

B

C

D

Cancer

• Uncontrolled cell division

• Tumors begin with a single cell that reproduces by mitosis– Cells in tumors divide continuously

• Metastasis: Process in which cells are invasive and move to other sites in the body

How does it happen?

• Two classes of genes: Oncogenes and tumor suppressor genes– Proto-oncogenes: control cell division – Tumor suppressor genes turn off cell division

p. 181

4Cell

division

Mitosis

3DNA

repair

G21

Cell grows,

doubles in size

G1

S

2Chromosome

duplication

G2/M checkpoint

G1/S checkpoint

Stepped Art

• Checkpoints in the cell cycle regulate cell division

The Cell Cycle and Cancer

• Neoplasm- abnormal growth of cells • Benign neoplasms are not cancerous

– Encapsulated; Do not invade neighboring tissue or spread

• Malignant neoplasms are cancerous – Not encapsulated; Readily invade neighboring

tissues – May also detach and lodge in distant places –

metastasis

Stages of Cancer

• 4 stages, – 1 = not so bad – 4 = really bad

• Stage I – localized to one part of the body Stage II - locally advanced

• Stage III - also locally advanced• Stage IV - often metastasized, or spread

Causes of Cancer

• Mutation: change in genetic makeup

• A factor which brings about a mutation is called a mutagen.

• Any agent that causes cancer is called a carcinogen and is described as carcinogenic.

What Causes Cancer?

Lifestyle

Environment

Family History

Lifestyle Risks

• Smoking

• Diet high fat and low in fruits and vegetables

• Lack of exercise

• Unprotected exposure to the sun, (UV) rays

• Obesity

Environmental Risks

• Second hand smoke

• Air pollution

• Industrial pollution

• Chemical exposures– tar from cigarettes– some foods

Inherited Risks

• Less than 15% of cancers are inherited• Gene mutations are linked to some inherited

cancers• Cancers that may be caused by inherited gene

mutations are:– Colon cancer– Breast cancer– Ovarian– Prostate cancer– Skin cancer

• Some families are more susceptible to getting certain cancers. – Remember you can’t inherit cancer its just that you

maybe more susceptible to getting it.

Stress

• There is connection between stress, immune system and cancer, that is changing the direction of research – it now appears that cancer cells make proteins

that actually tell the immune system to let them alone and even to help them grow.

Other ways• Many forms of cancer related to:

– Physical surroundings– Personal behavior– Or both

• At least 50% of all cancer can be attributed to some type of environmental factor

Treatment

Chemotherapy treatment • uses medicine to weaken and destroy cancer

cells in the body, including cells at the original cancer site and any cancer cells that may have spread to another part of the body.

• a systemic therapy, which means it affects the whole body by going through the bloodstream.

TreatmentRadiation therapy (also called radiotherapy)• high-energy rays are used to damage cancer

cells and stop them from growing and dividing.

• A specialist in radiation therapy is called a radiation oncologist

• Like surgery, radiation therapy is a local treatment; it affects cancer cells only in the treated area

Cancer Prevention

Healthy lifestyle • Exercise and proper breathing • Balanced diet• Complete rest and sleep • Water • Eating Fruit

lab

How does one go about getting cancer (name 2 ways)?

Agenda for Friday Jan 9th 1. Quiz2. Cancer lab

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Mitosis Foldable

Go to Page 243

Follow those directions

Homework

• Page 253 – 257• Questions 1 – 7 on page 257