Cancer :A Genetic Disease

Drill:

1. Write down 1 thing you know about the disease.

2. What would you most like to learn about cancer / What question would

you most like answered?

It affects millions of lives every year – so always use respect

when discussing cancer

What is Cancer?• Cancer is a growth of cells that do not stop

dividing. It is a progressive disease.

Benign vs. Malignant Tumors

• A Benign (buh-nine) tumor is one made of cells that don’t spread around the body.

• A malignant (aka cancerous) tumor is made of cells that can spread throught the body and make new tumors.

What causes cancer?• Mutations in

certain genes cause the cancer cells to divide without stopping. (Normal cells stop growing when they’re in contact with other cells)

What causes these mutations?

• Anything that can cause mutations in cells is a carcinogen.

Ok… but what causes mutations?

1: Certain chemicals can alter a DNA sequence by changing the sequence of bases.

2: Radiation:Careful with that Sunlight!

3: Viruses• Many viruses, like this one

(HPV) can insert their genetic information into the DNA of their hosts. This mutation can sometimes lead to cancer.

• HPV causes genital warts & is strongly linked with cervical cancer.

• Why do you think the HPV vaccine (approved in the last year) is controversial?

Mutation Happens

• Mutations happen all of the time in your body – but your cells have a lot of tricks for keeping your DNA in good shape!

The DNA Repair Kit• The DNA repair kit

is a group of enzymes that fix mutations when they happen.

• Cells may commit suicide (called apoptosis) when important genes malfunction, preventing cancer.

Broken Repair Kit = bad news.

• Some mutations cause the repair kit to malfunction.

• For example, a mutation in a gene that makes a DNA repair enzyme might make a non-functional protein or no protein at all!

• Cells with bad repair kits will then accumulate more mutations

It’s Probability! That’s why cancer rates increase with age.

What we’ve seen so far:

• Cancer is an uncontrolled growth of cells.– What process isn’t controlled anymore?

• Cancer is a progressive disease.–Malignancy is one of the most dangerous

characteristics of cancer – what is it?

• Cancer is caused by mutations in DNA that affect cell growth and function

• Cancer cells accumulate more mutations.

Can it be prevented?

• Yes, but not 100%

• Anything that reduces the number of mutations your cells suffer reduces your chances of developing cancer, so…

Are some people “predisposed” to cancer? YES

• Being born with certain mutant forms of different genes can affect your chances of developing cancer.

• For example – if some of your DNA repair mechanisms don’t work, you’re more likely to accumulate mutations.

• If science could tell you approximately when you might develop cancer, would you want to know?

What genes are involved? Hundreds, perhaps thousands.

• DNA microarrays like this one can show which genes a cell is transcribing, and how fast.

• By comparing cancer cells to normal cells, scientists can identify what’s going wrong in cancer cells

Is cancer always fatal? NO!

Treatments

• Surgery

• Chemotherapy– Uses modified nucleotides to cause rapidly dividing

cells (like cancer cells) to mutate and die off.

• Radiation– Targets the cancer cells and destroies them.

The Future

• Individualized genetic fixes• Drugs targeted to cancer cells• Gene therapy (inserting new genes to a

person)• Better screening• Better tissue transplants – stem cells?• Nanobots?

Exit Ticket & Homework

• Read “Cancer” pp . 211-214

• Exit Ticket: Answer the following questions before you leave!

1. What is cancer?

2. What causes cancer?

3. What cell process is uncontrolled in cancer cells?