GENETICSGene Control, Cancer and

Genetic Techniques

All cells have the same DNA, but not all cells produce the same proteins; how does this happen?

GENE CONTROL Gene expression controlled by:

Using promoters—sections of DNA that bind RNA polymerase to make mRNA

Using repressors—proteins that bind DNA to turn off genes

Permanently turning off genesControl RNA splicing

CANCER Uncontrolled, abnormal cell division Cancer can be caused by genetic

factors, environmental factors, or a combination of both

ONCOGENE A gene that causes a cell to become

cancerous A gene can become an oncogene in 3 ways:

Mutation occurs in a growth-factor gene (a gene that controls cell division)

Error in DNA replication results in multiple copies of a single growth-factor gene

A change in a gene’s location

TUMOR SUPPRESSOR GENE Gene responsible for preventing

uncontrolled cell growth If a gene mutation occurs in a tumor

suppressor gene so that it does not work anymore, uncontrolled cell growth could result

CARCINOGEN & MUTAGEN Carcinogen: an agent that causes or

tends to cause cancer (ex: UV radiation or tars in cigarette smoke)

Mutagen: a factor in the environment that can cause mutations in DNA (ex: radiation)

REDUCING CANCER RISK Screening tests such as mammograms,

Pap smears and prostate screenings should be done

Healthy behaviors:Avoid smokingEat a low fat dietEat a high fiber dietUse sunscreen

DNA FINGERPRINTING Procedure that creates a DNA profile Because no two people on this earth can

have the same DNA (with the exception of identical twins), each profile is unique to each person, like a fingerprint

USES FOR A DNA PROFILETissue Matching: used to match crime scene evidence to a suspect or to help identify a bodyInheritance Matching: used to determine paternity

TISSUE MATCHING EXAMPLE

The two samples must have the same band pattern

INHERITANCE MATCHING EXAMPLE

Each band in a child’s DNA fingerprint must be present in at least one parent

CREATING A DNA FINGERPRINT1. Extraction: DNA must be removed from

the nucleus of the cells

CREATING A DNA FINGERPRINT (CONT.)2. Restriction Fragments: Restriction

enzymes are used to cut apart the DNA at specific sites

CREATING A DNA FINGERPRINT (CONT.)3. Amplification: Polymerase

Chain Reaction (PCR) generates multiple identical copies from trace amounts of DNA

CREATING A DNA FINGERPRINT (CONT.)4. Electrophoresis:

In this process, DNA fragments created through PCR are separated by using an electrical fieldDNA is negatively charged and will move towards a positive electrodeThe smaller the fragment, the faster it will travel