MCM Final

Question 1

1) explain the intended function of Ara-C (cytarabine/arabinosylcytosoine)
2) by what mechanism is this function achieved

Answer 1

1) DNA polymerase inhibitor. inhibits DNA synthesis
2) Ara-C contains arabinose sugar; converted by animal cells to Ara-CTP, competetive inhibitor of DNA polymerase. commonly used to treat leukemia

Question 2

explain hereditary colon cancer and how it relates to the MER complex

Answer 2

mutations in one of the alleles of genes for MER complex (MSH2, MLH1) are predisposed. mutation in remaining good copy of genes would mean the MER system is nonfunctional and allow tumor development

Question 3

explain xeroderma pigmentosum (XP) and how sunlight affects individuals with this disease

Answer 3

UV light causes cyclobutane thymine dimers to form in the DNA. normally this is repaired using NER. XP patients, have abberant NER complex proteins (XP-A through XP-G) and cannot repair the damage. leads to squamous cell carcinoma and melanomas

Question 4

explain Cockayne syndrome, the symptoms observed, and the process that is abberant that leads to this condition

Answer 4

ERCC 6 & 8 are messed up
inability to carry out TCR (transcription coupled repair)
patients exhibit sensitivity to light, developmental and neurologic delay and usually die by age 20

Question 5

explain how BRCA mutations can lead to breast cancer

Answer 5

BRCA1 & 2 are tumor suppressor genes
mutations in these genes make women 5X more likely to develop breast or ovarian cancer before menopause
men can develop breast cancer too
can lead to basically any other type of cancer as well