Cell Bio Ch 20 Flashcards
______ is a disease of multicellular organisms
cancer
cancer occurs when ____
somatic cells incur mutations that prevent them from “behaving” and begin to divide uncontrollably
two properties of cancer cells
- they reproduce in defiance of normal constraints on cell growth
- they invade and colonize territories normally reserved for other cells.
a benign tumor
multiplies in one are and does spread into other types of tissue
malignant tumor
a tumor that has spread into other types of tissue from the one it started in.
metastases
secondary tumors derived from the cells that break off the primary tumor
cancer classifications
- carcinomas
- sarcomas.
- leukemias and lymphomas
carcinomas
derive from epithelial cell
sarcomas
derive from connective tissue or muscle cells
leukemias and lymphomas
derive from white blood cells
when most tumors are found they have about ________ cells
a billion
carcinogenesis
the production of cancer
mutagenesis
mutation in DNA
causes of mutagenesis
- radiation - x rays, radon, UV light
2. mutagens - chemicals in the environment; viruses
carcinogenesis is usually caused by _________
mutagenesis
a single mutation is ________ to cause cancer
not enough
cancer is cause by
a progressive accumulation of random mutations
carcinogen
cancer causing agent
incidence of cancer ______ upon exposure to a carcinogen
increase
multiple mutation, at least _____, are responsible for cancer
at least five
Both ______ and ______ changes can lead to cancer
genetic
epigenetic
genetics changes
modifications in the DNA sequence
epigenetic changes
alter gene expression through packing of DNA or changing patterns of DNA methylation
Many cancer cells have mutations in
genes involved in DNA repair or enzymes responsible for epigenetic control of gene expression
cancer stem cells
are capable of indefinite self-renewal
most cells in a tumor are not capable of
independently forming new tumors
normal cell division, normal apoptosis
homeostasis
cell produced from cancer stem cells, most have a ________
limited capacity for self-renewal
How do cancer stem cells arise?
- normal stem cells that acquire a mutation
2. a highly differentiated cell (transit amplifying cell) can acquire the capacity for prolonged self-renewal
cancer is difficult to eradicate because:
all cancer stem cells must be killed in a patient
In order to metastasize, malignant cancer cells must________
break free from their current environment, and survive and proliferate in a foreign environment
tumors induce ________ or the development of new blood vessels to feed the tumor
angiogenesis
cancer cells do not ct in isolation but are supported by the ______ - epithelial cells such as __________ and ___________ that help sustain the tumor.
stroma
fibroblasts and white blood cells
genes that have been found to be alter in various human cancer are referred to as:
cancer-critical genes
two classes of cancer critical genes
proto-oncogenes
tumor suppressor genes
what should be considered a third class of cancer critical genes?
DNA maintenance genes
proto-oncogenes
overactive or overexpressed forms of these genes promote cancer and are called oncogenes
tumor suppressor genes
inactive forms of these genes contribute to cancer development
overactivity mutations (like oncogenes) require mutation in
one gene
underactivity mutations (like tumor suppressor genes) require mutation in
two genes
Ways that proto-oncogenes can be made overactive
mutation in coding sequence, gene amplification, chromosome rearrangement
over activity - mutation in coding sequence
hyperactive protein made in normal amounts
over activity - gene amplification
normal protein greatly overproduced
over activity - chromosome rearrangement
two types:
- nearby regulatory DNA squence causes normal protein to be overproduced
- fusion to an actively transcribed gene produces hyperactive fusion protein
way sof eliminating normal Rb genes, or tumor suppressor genes
- nondisjunction causes chromosome loss
- chromosome loss then chromosome duplication
- mitotic recombination
- gene conversion
- deletion
- point mutation
5 types of treatment for cancer
- Surgical methods
- Radiotherapy or DNA-damaging chemotherapy
- targeted treatment
- Block formation of the new blood vessels
- Target products of specific oncogenes
radio therapy or DNA-damaging chemotherapy treatment for cancer
cancer cells lack normal checkpoint mechanisms so they are genetically unstable and can be killed by these radio- or chemotheray
target treatment for cancer
using a medication that targets a weakness in the cancerous cells that causes them to kill themselves or be unable to divide.
block formation of new blood vessels - treatment for cancer
keep tumor from creating blood vessels to feed their growing needs
color codes in DNA microarray (DNA chips)
red - gene amplification
green - gene loss
