10.3 and 10.4 Notes

Control of the Cell Cycle

• The cell cycle is controlled by proteins called cyclins and enzymes that bind to those proteins

• Regulation can be internal or external depending on whether the signal to divide comes from inside or outside the cell

Apoptosis

• A process of programmed cell death• Occurs naturally during development or

can be a result of diseases such as Parkinson’s or AIDS

Cancer

• When the segment of DNA (gene) that codes for the regulatory proteins is damaged the cell may divide uncontrollably

• Cancer is a growth (tumor) resulting from uncontrolled cell division

Cancer

• Scientists have identified p53 as a tumor suppressing gene that controls cell division

• Cells with damaged p53 genes do not respond to signals to divide normally.

Cancer

• Tumors can be benign or malignant depending on whether they affect healthy cells

• Malignant tumors affect surrounding healthy tissue by depriving them of nutrients or blocking nerve connections

• Sometimes cancer can travel to other parts of the body, this is called metastisis

Cancer Causes and Prevention

• Can be caused by genetic or environmental factors (ex: cancer runs in families, smoking, pollution, UV rays)

• Healthy choices about diet, exercise and tobacco use can help prevent cancer

Screening for Cancer

• Doctors can use imaging techniques such as radiology to search for cancer

• Biopsies involve taking a sample of cells or tissues to examine

Do You See the Gorilla?

80% of radiologists did not!

Cancer Treatments

• Surgery if tumor is contained• Radiation targets cells that divide rapidly• Chemotherapy consists of chemical

compounds that target dividing cells and can therefore interfere with normal division in healthy cells

• Fluorescence microscopy allows scientists to label parts of the cell and view the phases of the cell cycle in more detail

http://images.wellcome.ac.uk/indexplus/obf_images/3e/cf/46fa21b8a66206e8763cf29f58d4.jpg

Check For Understanding…

1. The type of protein which controls the cell cycle is

a. tubulin

b. keratin

c. cyclin

d. collagen

2. Which of the following best describes apoptosis?

a. programmed cell death

b. cancer cells migrate to other parts of the body

c. cells divide repeatedly

d. taking a sample of cells

3. Which disease is a result of uncontrolled cell division?

a. diabetes

b. flu

c. cystic fibrosis

d. cancer

4. Which of the following is most likely to result from a malignant tumor?

a. cancer migrates to a different part of the body

b. rapidly dividing cells are destroyed

c. it remains isolated and usually harmless

d. genetic mutations

5. Which of the following is NOT a potential cause for cancer?

a. genetics

b. tobacco

c. lots of fruits and vegetables

d. UV radiation

Cell Differentiation

• Each of us starts life as a single cell• All multicellular organisms pass through

the stage called an embryo

• Cells become specialized for perform different functions through the process of differentiation

• Scientists can map the fate of every single cell division in some organisms ( C. elegans)

Stem Cells• Remember that every

living thing starts out as a single cell. That cell is said to be totipotent because it can become any type of cell.

• Cells that are pluripotent can develop into most, but not all, cells in the body.

• Stem cells are undifferentiated cells from which specific cell types develop. There are two types of stem cells– Embryonic stem cells

which are pluripotent and can become most cell types

• Adult stem cells which are found throughout the body after development and are multipotent because they can develop into several different types of cells

Stem Cell Research

• Benefits: stem cells offer the benefit of using undifferentiated cells to replace or repair those damaged by heart attack, stroke or spinal cord injury

• Ethics: most ethical questions come from obtaining embryonic stem cells because harvesting the cells causes destruction of the embryo– The funding of stem cell research has

become an important political issue– It is controversial because the arguments for

and against involve ethical issues of life and death

Technological Solutions

• There has been research suggesting it's possible to extract a small number of stem cells from an embryo without damaging it

• It may also be possible to switch “on" and reprogram adult stem cells so they can differentiate into a greater variety of cells

Check For Understanding…

1. Cells becoming specialized to perform different functions is known as

a. metastasis

b. differentiation

c. apoptosis

d. chemotherapy

2. Cells that can become any type of cell are known as

a. totipotent

b. pluripotent

c. multipotent

d. adult stem cells

3. Embryonic cells that can become most, but not all, cell types are called

a. totipotent

b. pluripotent

c. multipotent

d. adult stem cells

4. Adult stem cells can become several different types of cells. They are known as a. totipotent

b. pluripotent

c. multipotent

d. adult stem cells

5. Which of the following is NOT a benefit of stem cell research?

a. treating stroke victims

b. treating heart attack victims

c. treating cancer

d. treating spinal cord injuries