Video #: Cancer and its Causes
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Reference Pages: Ch. 3 Pgs. 93-96 (old text or 105-107new text - PowerPoint PPT Presentation

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Video #: Cancer and its Causes Go to this site: Scroll down & Find “ Session 8: Cell Biology & Cancer Click on “VoD” and watch. Reference Pages: Ch. 3 Pgs. 93-96 (old text or 105-107new text

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Reference pages ch 3 pgs 93 96 old text or 105 107new text

Video #: Cancer and its CausesGo to this site: down & Find “ Session 8: Cell Biology & CancerClick on “VoD” and watch

Reference Pages: Ch. 3 Pgs. 93-96 (old text or 105-107new text

**While watching the video be sure to have a minimum of 15 key statements. Some of your statements should address:

What was thought to be the cause of cancer in the earlier years? What do we know today in regards to the causes of cancer?

Differences between an Oncogene and a Tumor suppressor gene and what these genes specifically do.

The RAS gene and p53 gene and what they do. Which one is a proto-oncogene

Why is the p53 gene considered to be the “Guardian Angel of the cell” Give three things that is does.

How has the study of Telomeres and the enzyme Telomerase contributed to our knowledge of cancer.

Genes that cause cancer useful when watching the video
Genes that Cause Cancer(useful when watching the video

  • Genes: are the A, T, C, G sequences that are used to make proteins in all of our cells. When genes get “expressed” a portion of the DNA is used to make a particular protein.

    (**genetic expression = protein synthesis)

  • Oncogenes: cause cell division to continue at a faster & faster rate. Other genes are activated that normally are “off”

    (Ex. From video: ras gene) – seen in 30% of all cancers

  • Proto-Oncogenes: normal genes that code for normal cell growth and division

  • Tumor Suppressor Genes: normally inhibits cell division and prevents uncontrollable cell growth. Typically, these genes stops tumors from growing. When mutated, this ability is lost.

    (Ex. From video: p53 gene) – seen in 50% of all cancers

    *Environmental factors can change how genes get expressed

Characteristcs of cancer pg 95
Characteristcs of Cancer(Pg. 95)

Mitosis gone Haywire (uncontrolled cell division)

Cells develop & no longer have their specialized function (unable to produce what they are supposed to produce)

All they do is make more cancer cells

Will induce blood vessels to grow (angiogenesis)

Has the ability to spread (metastasize)

Cells will divide and grow into tumors

Benign (non-cancerous) vs. -Malignant (cancerous)

Mitotic clock mechanisms in cells telomeres proteins cell size sa hormones growth factors
Mitotic Clock Mechanisms in CellsTelomeres, Proteins, Cell size (SA), hormones, & Growth factors

Telomeres: Segments of DNA (200 repeated sequences of nucleotides) are lost at the tips of the chromosomes with each mitotic event.

(Mitotic clock) the tips of chromosomes wear down and lose DNA sequences over time.

Six Nucleotide sequence repeated hundreds of times

1,200 nucleotides are removed after each mitotic event


Short, non-coding pieces of DNA

Contains repeated sequences (ie. TTGGGG 20 times)

Can lengthen with an enzyme called Telomerase

Lengthening telomeres will allow more replications to occur.

Telomerase is found in cells that have an unlimited number of cell cycles (commonly observed in cancer cells)

Artificially giving cells telemerase can induce cells to become cancerous

Shortening of these telomeres may contribute to cell aging and Apotosis (programmed cell death)

Ex. A 70 yr old person’s cells divide approx. 20-30X vs an infant which will divide 80-90X