Mutations !

Gene mutation

Change in DNA base sequence

Permanent

Only inherited if occur in gametes

2 types Spontaneous

Errors in normal processes, rare Ex. DNA segment moving from one location to

another Induced

Exposure dependent (ex. Chemicals, radiation)

Basic Terminology Mutagens

Environmental agents known to create mutations within DNA (ex. UV radiation)

Carcinogens Mutagens that cause cancer “cancer-causing” Ex. Smoking, chemicals used in industries, DDT

**Cancer—accumulation of mutations over time**

What is so bad about radiation?

FREE RADICALS ! ! ! React with DNA—

MUTATION! Ex. X-Rays

DNA Technology

Gel Electrophoresis

Laboratory process for DNA fragment separation.

DNA separates based on the size of each DNA fragment

Restriction enzyme sites (where enzymes will cut DNA) unique to each person SO expose DNA to restriction enzymes

Latest Technology

Getting rid of our reliance on gel electrophoresis….any problems with old method?

Fluorescent labeling of DNA fragments

Creates a graph or “DNA fingerprint” showing repeat numbers based on how much fluorescence is present.

Cancer: the basics

Uncontrolled cell growth

Accumulation of mutations within genes

Gradual development

Cancer: the basics (cont.)

Proto-oncogenes Proteins formed from these genes maintain cell

cycle and stop apoptosis Mutations within these genes form oncogenes

(maintain cell cycle, always simulated, do not listen to signals or conditions to stop)

Examples: ras gene, BRCA 1 oncogene (breast/ovarian cancer)

Cancer: the basics (cont.)

Tumor suppressor genes

-proteins formed from these genes prevent cell cycle and signal apoptosis

Prevent uncontrolled cell cycles and cell division with damaged DNA

Mutations within these genes cause the cell cycle to continue without control

Ex. Common ones seen in human cancer—RB, p53 genes for corresponding proteins

What can cause mutations leading to

cancer? Genetics/Heredity

-certain individuals are more susceptible than others

Viruses

Environmental factors Chemicals Smoke UV/radiation exposure—skin cancer

Cancer Terminology Cancer in situ– tumor at primary site

Tumor: When cancerous cells divide, they form a mass of

cancer cells within an otherwise normal tissue

Benign tumor: Cancerous cells remain in one spot Growth does not continue Noncancerous

Malignant tumor: Cancer cells become invasive enough to impair

the functions of one or more organs Cancer cells have the ability to spread

Cancer Cell Terminology (cont.)

Metastasis: The spread of cancer cells beyond their original site-Cancer cells can break away from tumor to invade other

locations throughout the body

Angiogenesis: The process where cancer cells develop their own blood

supply to obtain continued nutrients so they can keep growing.

New blood vessels and the cancer cells use these to “fuel” their growth

Treatments can fight this process

How do we know a cell is cancerous?—Cancer Cell

Traits

1) No differentiation

-no function, abnormal appearance, unspecialized

2) Abnormal Nuclei

-larger nucleus

-abnormal chromosome numbers, more

3) No apoptosis

-do not respond to signals from cell about abnormality or DNA damages

-evade detection from the body’s immune system

-do not die

How do we know a cell is cancerous?—Cancer Cell

Traits

4) No contact inhibition/ anchor

-cancer cells do not “listen” to neighbors

-continue to grow despite being crowded by neighbors—tumor results

5) Go through metastasis

-break away from tumor and invade other cells throughout the body

6) Go through angiogenesis

-create blood supply to provide nutrients for continued growth

Normal v. Cancer Cells Have density-

dependent inhibition

Will only divide when attached to a substrate (anchored)

Must have sufficient growth factors or nutrients for division

Lack density-dependent inhibition

Will divide in solution or when not anchored

Unaffected by presence of external growth factors or nutrients