Cancer Genetics Flashcards
Three key checkpoints in cell cycle control
- G1/S - monitors for proper cell size and undamaged DNA
- G2/M - holds up cycle until replication and DNA repair are complete
- M Checkpoint - proper spindle formation and attachment
Tumor
mass of abnormal cells that don’t have normal controls on cell division
Benign
noncancerous abnormal cells remain localized
Malignant
cancer cells invade surrounding tissue
Metastatic
cancer cells spread and make secondary tumors
Most cancers are sporadic and influenced by the…
environment
High incidents of cancer correlate with tissues that…
undergo more cell divisions due to errors in replication.
Tumor suppressor genes…
prevent “bad” cells from diving uncontrollable
Proto-oncogenes
promote cell division, allow “good” cells to divide
Most cancers are not ________ but are based on _______ factors
inherited, environmental
What role does loss of function mutations play in the origin of tumors?
They cause complete or partial absence of protein function
What role does the gain of function mutations play in the origin of tumors?
The cell may produce proteins that are not normally present
Tumor suppressor genes produce factors that _______ cell division
inhibit
What is the normal function of BRCA1 gene and which cancer when mutated is it correlated with
Function: DNA repair, transcription factor
Cancer: Breast & Ovarian
What is the normal function of p53 gene and which cancer when mutated is it correlated with
Function: regulates cell division, apoptosis, DNA repair, and other functions, acts like a “fork in the road”
Cancer: Many types of cancer
What is the normal function of RB gene and which cancer when mutated is it correlated with
Function: regulates cell division
Cancer: Retinoblastoma & many others
BRCA1, p53, and RB are all examples of what types of genes
tumor suppressor genes
What is Knudson’s Two Hit Hypothesis
says that both chromosomes have to be defective in the same cell to allow tumors to develop
Tumor Suppressor Retinoblastoma-RB Gene Mechanism
-G1 to S transition
-RB normally prevents E2F from activating replication
-Late in G1, RB releases E2F and Replication can begin
Tumor Suppressor p53 Gene Mechanism
-Functions at G1 checkpoint
-The fork in the road: if DNA is damaged p53 delays cell division until the damage is repaired or programs cell to die
Tumor suppressor mutations are typically _________. Low damage _____ and high damage ________
recessive, blocks the cell cycle and causes cell death
Mutations in proto-oncogene results in ______ that allows ________.
oncogene, uncontrolled cell division
Oncogenes are (dominant/recessive) acting mutations
dominant
What is the normal function of c-myc gene and which cancer when mutated is it correlated with
Function: transcription factor
Cancer: Burkitt’s Lymphoma, leukemias, neuroblastoma
