Cancer Genetics Exam Questions with Verified Answers Latest Update (Rated A+)

Cancer Genetics Exam Questions with Verified Answers Latest Update (Rated A+) What is Cancer? - Answers Tumorigenesis Metastasis Carcinogenesis Tumorigenesis - Answers Loss of control of cell division Induce genes that promote cell division Repress genes that inhibit cell division Deregulation of apoptosis Angiogenesis Metastasis - Answers Nodal involvement Organ involvement Carcinogenesis - Answers the production, development, or origin of cancer Environmental carcinogens - Answers Mutate somatic cell DNA Interrupt normal cell cycle Tumor formation Inherited Cancer: The Two-Hit Model - Answers Retinoblastoma Inherited: Affected parent Affected offspring 50% Bilateral Non-inherited: no familial pattern Unilateral Two-Hit Model: Inherited form already has one copy of abnormal gene Non-inherited form has acquired two mutations in somatic cells Tumor Suppressor Genes - Answers Normally block uncontrolled cellular proliferation Therefore, suppress tumor formation Usually involved in regulating cell cycle Recessive at the cellular level Require two copies of mutant allele to form tumor Somatic (non-tumor) cells will still be heterozygous Proto-oncogenes - Answers Produce 4 basic regulators of cell growth Growth factors Growth factor receptors Signal transduction molecules Nuclear transcription factors Mutation in proto-oncogene Oncogene Unregulated cell growth and differentiation Dominant at the cellular level -gain-of-function mutation Very rarely present in the germline Senescence - Answers Telomeres at ends of chromosomes shorten with each cell division After 50 -70 cell mitotic events, telomeres depleted --senescence--apoptosis Tumor cells activate gene for telomerase Adds telomeres to newly divided cells Allows for continued cell division Rarely found in normal cells Telomerase present in up to 90% of tumor cells TP53 - Answers -Mutations in TP53occur in half of all human tumor types (50 types isolated so far) -TP53codes for p53 -1st function of p53: Halt cell cycle for DNA repair to occur prior to S phase 2ndFunction of p53: - Answers -Induce apoptosis if DNA damage is beyond repair -If problems with normal function of pRbpathway of repair, then apoptosis induced by p53 If problems with TP53(i.e. mutation): - Answers -Can not repair damage prior to replication -Can not induce apoptosis of cells with DNA damag TP53 and Clinical Prognosis - Answers Tumor tissue analysis to determine prognosis TP53mutations carry particularly poor prognosis Associated with aggressive form of cancer Therapeutic potential Insertion of "normal" TP53into tumors with TP53mutation Induces apoptosis in transfectedcells Results in tumor regression Fraught with typical problems of gene therapy TP53and Li FraumeniSyndrome (LFS) - Answers Autosomal dominant (at the organismallevel) Early onset ½ develop invasive cancer by age 30 90% have primary tumor by age 70 Often multiple primary tumors Breast, Colon, Soft tissue sarcoma, Osteosarcoma, Brain tumors, Leukemia, Adrenocorticalcarcinoma 75% have mutations in p53 (two-hit model) Remainder have mutation in CHEK2which activates p53 TP53 and Toxins - Answers AflatoxinB1 Present in Aspergillussp.