Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is...

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Molecular Biology of Cancer • What are the environmental influences that are cancer-causing? • What is the difference between an oncogene and a proto-oncogene? • What genetic changes convert proto-oncogenes to oncogenes? • Reference page 272 (Fig 15.12) to understand alterations of chromosome structure: relate this to the statement “Malignant cells are frequently found to contain chromosomes that have broken and rejoined incorrectly, translocating fragments.”

Transcript of Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is...

Page 1: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Molecular Biology of Cancer

• What are the environmental influences that are cancer-causing?

• What is the difference between an oncogene and a proto-oncogene?

• What genetic changes convert proto-oncogenes to oncogenes?

• Reference page 272 (Fig 15.12) to understand alterations of chromosome structure: relate this to the statement “Malignant cells are frequently found to contain chromosomes that have broken and rejoined incorrectly, translocating fragments.”

Page 2: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Molecular Biology of Cancer (responses)

• Chemical carcinogens, physical mutagens (X-rays) or certain viruses

• Proto-oncogene: normal cellular genes-code for proteins that stimulate normal cell growth and division

• Oncogene: cancer-causing gene• “An oncogene arises from a genetic change

that leads to an increase in either the amount of proto-oncogene’s protein product or intrinsic activity of each protein molecule”

Page 3: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Cancer Understood

• Explain how the location of the proto-oncogene being located adjacent to an active promoter leads to an oncogene.

• What is amplication?• Explain how a point mutation can change the

gene’s protein product and therefore lead to an oncogene.

Page 4: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Alterations of Chromosome Structure

Page 5: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

3 Main Categories of Oncogene Conversion

• Movement of DNA within the genome – Translocation or transposition– **new controls / new promoter

• Amplication of proto-oncogene– Increases number of copies of the gene in the cell

• Point mutation in proto-oncogene– More active or resistance to degradation than

normal protein• **All growth stimulating**

Page 6: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Proto-oncogenes into Oncogenes

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Oncogenes

• http://www.teachersdomain.org/asset/tdc02_vid_oncogene/

Page 8: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Tumor-suppressors

• Define and explain tumor-suppressor genes in relationship to cancer.

• What are the functions of normal tumor-suppressor genes?

Page 9: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Tumor Suppressor Genes

• Tumor suppressor genes—proteins prevent uncontrolled cell growth

• Functions:– Repair damaged DNA– Control adhesion of cells to each other– Cell signaling—inhibit cell cycles

• If altered, the suppression is decreased and therefore cancer can be the outcome

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Ras (30%) versus p53 (50%)

• In general, what is the difference between a oncogene and a tumor suppressor gene? Relate them to cancer.

• Signal transduction Pathways: A set of chemical reactions in a cell that occurs when a molecule, such as a hormone, attaches to a receptor on cell membrane. The pathway is actually a cascade of biochemical reactions inside the cell that eventually reach the target molecule or reaction. Thus, the pathway is a method by which molecules inside the cell can be altered by molecules on the outside.

Page 11: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Ras

• Normal ras job:• What does ras need to do its job?• How is the oncogene of Ras hyperactive?

Page 12: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

p53

• What are the main functions of a normal functioning p53? (hint: at least 3 ways)

Page 13: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Cancer and Age

• Why does the incidence of cancer increase with age?

• How does this help explain the predispositions to cancer that run in some families?

• Explain “dominant oncogenes and recessive tumor-suppressors”.

• How do active telomerases relate to cancer?

Page 14: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Viruses

• How do they contribute to cancer development?

• Define retrovirus (use back of book)

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BRCA1 and BRCA2

• What does BRCA stand for?• What type of cancers are these genes related

to?• What type of genes are these? (oncogenes or

tumor-suppressors)

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Metastasis

• Tumor• Benign• Malignant• Metastasis

Page 17: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Khan

• http://www.youtube.com/watch?v=RZhL7LDPk8w

Page 18: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• True or False: A proto-oncogene only makes a protein when a promoter tells it to.

Page 19: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• True

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Question:

• True or False: One possible effect of an oncogene is the inability to repair a damaged cell.

Page 21: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• False

Page 22: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• What is translocation?

Page 23: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• Exchange of information from one chromosome to another.

Page 24: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• What does translocation have to do with promoters and cancer?

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Answer:

• The “switched gene” goes to a new location with a new promoter that tells it to turn on (make a protein) when it normally would not.

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Question:

• What are the three normal jobs of a tumor-suppressor?

Page 27: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• Repair damaged DNA• Control adhesion of cells to each other• Cell signaling—inhibit cell cycles

Page 28: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• Was the video showing how a mutated Ras works or how a mutated p53 works? Explain.

Page 29: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• Ras. It was stimulating cell growth, not stopping it. Ras is an oncogene, not a tumor-suppressor.

Page 30: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• Why is p53 known as the Guardian Angel of the Genome? Why is p53 a part of 50% of all cancers?

Page 31: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• It makes sure all the erred cells do not multiply or continue on with mutations by repairing, signaling to stop cell cycle, or signaling apoptosis.

• An error in p53 is very detrimental to cells and leads to cell overgrowth…aka cancer.

Page 32: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• True or False: A virus can stimulate cancer.

Page 33: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• True

Page 34: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• True or False: It only takes a single mutation to cause cancer.

Page 35: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• False. This is why the incidence of cancer increases with age.

Page 36: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Question:

• BRCA genes are ___________________ genes.

Page 37: Molecular Biology of Cancer What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene?

Answer:

• Tumor-suppressor