Chapter 13: Viruses - Cancer Flashcards
What is a tumor?
- abnormal growth of tissue
What is a benign tumour?
does not spread
What is a malignant tumour?
- metastasize and invade nearby tissues (cancer)
What two genes control cell growth of cancer?
- proto-oncogenes
- tumor-supressor genes
What are proto-oncogenes?
- genes that stimulate cell growth
What are tumor-supressor genes?
- genes that inhibit cell growth
What do mutations in proto-oncogenes and tumor-supressor genes cause?
- leads to uncontrolled cell growth, tumor formation, and cancer
What are cancer causing viruses (oncogenic viruses)?
- carry oncogenes, which are genes that interfere with the cell’s control mechanisms
- most are DNA viruses
Most oncogenic viruses are DNA viruses. What are DNA viruses? (2)
- integrate viral DNA into the host xme as a provirus
- oncogenes continue to be supressed (grow indefinitely)
What is believed to be the cause of almost all cases of liver cancer?
Hep B and C
What is Epstein-Barr virus?
- causes infectious mononucleosis
- may cause lymphoma (cancer of WBC) and some cancers of the nose and throat
What is Human Papillomavirus (HPV)? (3)
- STD
- genital warts
- believed to cause almost all cases of cervical cancer (abnormal growth in reproductive system)
In lecture, Hep C is an ___ RNA/DNA virus?
RNA
In lecture, what is the most common STD
HPV
What are two virus-like infectious particles?
- viroids
- prions
What are viroids? (3)
- naked RNA
- No protein coat
- results in some diseases in plants, but not yet found in animals
What are prions? (3)
- infectious protein particles
- No genetic material (RNA/DNA)
- linked to several human and animal diseases
Give an example of disease caused by prions. (2)
Transmissible spongiform encephalopathies
- causes sponge-like holes in the brain
What is the mode of infection for prions?
- transmitted through food
What is the name of disease when these animals are infected by prions?
1) sheep
2) Cow
3) humans
sheep - scrapie
cow - mad cow disease
humans - variant creutzfeldt-Jakob disease
How can prions be destroyed? (2)
- not usually destroyed by high temperatures
- can be destroyed by heat (480C) or a combination of autoclaving in a solution of sodium hydroxide (base
How long does disease caused by prions last in humans? why?
- onset of disease in humans occurs several years after infection
- not clear why or how it accumulates in the brain
Why are prions so dangerous to us? (2)
- always fatal
- no cure or treatment
In lecture, why do prions occur?
- we all have forms of PrPc and the gene that codes forit causes a mutation
- instead of producing PrPc, the gene mutates and produces PrPsc
