exam prep Flashcards
in class we discussed two compounds that inhibit production of dTMP. What are these compounds and what specifically do they inhibit?
Flurouracil
- inhibit thimidylate synthase enzyme
methotrexate- inhibit the enzymatic conversion of dihydrofolate to tetrahydrofolate
your patient is suffering from gout-like symptoms. What treatment do you recommend? Why is this treatment effective
allopurinol
- will inhibit xanithine oxidase thus decreasing production of uric acid
- also binds to PRPP thus lowering the amount of purine synthesis
Will elevated PRPP levels increase, or decrease purine biosynthesis
increase
a defect in the enzyme ApeI will affect which DNA repair pathway
base excision repair
describe the specifics of a DNA repair pathway. What type of DNA lesion is corrected? What proteins detect the damage? how is it removed? how is it repaired?
Nucleotide excision repair
-repairs larger lesions in DNA, not just single nucleotides
-XPA and XPE detect the damage then XPB and XPD of TFIIH act as helicase
-XPE and XPG then remove the error
-DNA polymerase then replaces correct bases
ligase then seals the DNA
why does acetylation of histone N terminal tails often correlate with high transcriptional activity?
acetylation neutralized the positive charge of the histone-this decreasing the histones ionic interactions with the negative charge of DNA. this allows DNA to be exposed (TATA box, promoters) thus allowing transcription to occur more highly
what complex of proteins binds specifically to the TATA box
general transcription factors- TFIID-TBP(TATA binding protein)
transcription factors activation domains can stimulate transcription. Describe several ways that these domains can function.
activation domains such as acid blobs, proline rich or glutamine rich act to bridge info/relay between general transcription factors and DNA binding domain of transcription factors. they can also act to bring proteins to the transcription area- such proteins may act to speed up the initiation or process of transcription.
describe in detail cleavage/polyadenylation
when mRNA has a AAUAAA sequence produced on it, CPDF and CSH move from the CTD to the new mRNA. CPSF brings to the AAUAAA sequence, while CSTF beings to a GU. Cleavage factors 1 and 2 then act to cleave the mRNA near the CSTF. PAP then acts to initiate/produce a poly-A tail of around 200 onto the end of the mRNA- in this way the mRNA is cleaved and then a poly-a tail is added
what is the function in translation of the shine dalgarno sequence in bacterial mRNA
shine dalgarno ensures that the mRNA enters the ribosome correctly, so it may be read 5-3 and so that start condon may be found and initiate act of translation
if a viral RNA sequence contained an internal ribosome entry site, what eukaryotic translation protein would be dispensable for translation of the viral sequence?
eIF4E
???
bacterial EF-G is needed for which step in bacterial translation
moving the growing polypeptide attached to a tRNA from the Asite to the Psite and move RNA 3 nucleotides
you have normal and disease tissue samples from your patient. you would like to compare the gene expression profile in these samples. What diagnostic method would you use?
microarray assay
a mouse hepatitis virus outbreak has closed your lab facility. the outbreak appears to be contained because serological tests do not reveal viral proteins. However you suspect a low level of viral infection persists. what test would you use to detect trace levels of virus in your mouse blood samples?
PCR
your patient’s beta globin gene is silent due to DNA methylation. What compound could be given to demethylate the DNA and activate the gene?
5-azacytidine
