Chapter 20: Cancer Flashcards
What is cancer?
result of genetic alteration (mutations) that allow a cell to survive and divide when it should not
What are the two properties of cancer cell?
- Proliferate independent of normal constraints
- Invade and colonize areas normally reserved for other cells
What are the three types of cancer cells?
- Benign
- Malignant
- Metastasis
What are benign tumor
cells that remain cluster in a single mass but are not invasive
What are malignant tumors?
invasive tumor
What does it mean for a tumor to metastasis?
Tumor break off and colonize different area
What are the factors that can cause cancer?
Environment
Life style
Genetic predisposition
Birth place
Virus infection
What does the conversion of normal cell to cancerous cell require?
multiple mutations
Why does the chance that a cell becoming cancerous increase greatly with age?
cells are continually experiencing accidental changes to their DNA—which accumulate and are passed on to progeny cells when the mutated cells divide
What is genetic instability?
mutations that interfere with the accurate replication and maintenance of the genome and thereby increase the rate at which mutations accumulate.
How does sequential accumulation of tumor lead to cancer?
at each step, a mutation can enhance a cell’s ability to proliferate, or survive, or both, so that its progeny become a dominant clone in the tumor.
What are the two main class of gene critical for cancer?
Oncogene and tumor surpressor gene
What are oncogene?
mutated gene that has the potential to cause cancer
what are proto-oncogene
The normal form of the oncogenes
ex: ras
What are Tumor-suppressor genes
gene that regulates a cell during cell division and replication
ex: p53
What might happen if ras is mutated?
The oncogene is hyperactive, causing excess cell survival or proliferation
What happens if one of the p53 gene is mutated?
There will be no effect because p53 mutant are recessive. No effect is done unless another mutation comes in
What are the three ways a proto-oncogene can be converted to an oncogene
- Mutation in coding sequence
- Gene Amplification
- Chromosome Rearrangement
How can virus cause tumor?
the src gene in src containing virus triggers uncontrolled growth in abnormal host cells.
What distinguishes cancer cells from normal cells?
- Cancer cells have a reduced dependence on signals from other
cells for their survival, growth and division - Cancer cells can survive levels of stress and internal derangement that
would cause normal cells to undergo apoptosis. - Cancer cells can proliferate indefinitely.
- Cancer cells are genetically unstable.
- Cancer cells are abnormally invasive.
- Cancer cells are abnormally avid for nutrients, which they use to generate
ATP by glycolysis, useful in an oxygen-deprived environment of the center of
a fast growing tumor. - Cancer cells can survive and proliferate in abnormal locations.
- Cancer cells influence the behavior of their environment, producing signals
that support their survival.
Compare a normal ras from a mutated ras
Normal ras are rtk dependent and is activated by GDP/GTP exchange stimulated by GEFs. However, mutated ras can activate without GTP hydrolysis
What is causing cancer cell to survive stress conditions that would normally lead to normal cell undergoing apoptosis
mutations in p53 that
regulate the intracellular death program responsible for apoptosis
What would be the effect
of a mutation that
inactivate Rb on cell
division?
increased cell proliferation or increased cell death
Why can cancer cell proliferate indefinitely if normal cell can lose the ability to produce telomerase?
Telomerase is reactivated by cancer cell even if its activity is decreased, by passing cell senescence
