CH 23 Cancer Genetics – Flashcards
Unlock all answers in this set
Unlock answersquestion
invades other tissues
answer
malignant
question
process in which malignant tumor travels to distant sites in the body and forms secondary tumors
answer
metastasis
question
What types of evidence indicate that cancer arises from genetic changes?
answer
1. exposure to radiation & enviro mutagens cause higher incidences of cancer (damaged DNA 2. some cancers run in families 3. a few cancers are linked to chromosomal abnormalities 4. oncogenes & mutations cause proto-oncogenes to become oncogenes, or inactivate tumor-suppressor genes
question
How is cancer different from most other types of genetic diseases?
answer
Most cancers arise from genetic changes in somatic cells that arise during an individual's lifetime, whereas other types of genetic diseases are inherited through the germ line.
question
tumor cells acquire more mutations that allow them to become increasingly more aggressive in proliferating and eventually outgrow their predecessors and take over the clone
answer
colonial evolution
question
dominant-actin stimulatory genes that cause cancer
answer
oncogenes
question
inhibitory genes in cancer
answer
tumor-suppressor genes
question
normal cellular genes responsible for basic cellular functions, when mutated contribute to the development of cancer
answer
proto-oncogenes
question
enzymes that add phosphate groups to other proteins, only functional when associated with cyclin protein
answer
cyclin-dependent kinases
question
external signals (hormones & growth factors) trigger a cascade of intracellular reactions that stimulate/inhibit cell cycle
answer
signal transduction pathway
question
formation of new blood vessels
answer
angiogenesis
question
What is the difference between an oncogene and a tumor-suppressor gene?
answer
An oncogene stimulates cell division, whereas a tumor-suppressor gene inhibits cell growth.
question
Why do mutations in genes that encode DNA-repair enzymes often produce a predisposition to cancer?
answer
Mutations that affect DNA repair result in high rates of mutation. Mutations may convert proto-oncogenes into oncogenes or inactivate tumor-suppressor genes.
question
How do chromosome deletions, inversions, & translocations may cause cancer?
answer
All involve breakage & rejoining of chromosomal DNA, rejoining brings together segments of DNA that were previously distant from eachother. May inactivate tumor suppressor genes, put a strong promoter next to a proto-oncogene causing overexpression of the proto-oncogene, or may bring two parts of genes together creating a new oncogene.
question
How do viruses contribute to cancer?
answer
Retroviruses have strong promoters - may cause over expression of a proto-oncogene in the host genome. May inactivate tumor suppressor gene. Some retroviruses carry their own oncogenes, others express gene products that deactivate tumor suppressor proteins.
question
If cancer is fundamentally a genetic disease, how might an environmental factor such as smoking cause cancer?
answer
Environmental factors cause cancer by acting as mutagens. Higher rates of mutation cause higher rates of inactivation of tumor suppressor genes or conversion of proto-oncogenes to oncogenes.
