ASCP Molecular Biology Certification Exam| 321 questions| with complete solutions

Pyrimidine Correct Answer: One carbon ring Cytosine, Thymine, Uracil Purine Correct Answer: Two carbon rings Adenine, Guanine How are nucleotides joined together? Correct Answer: Condensation to form phosphodiester bond What is the function of mRNA? Correct Answer: Carries genetic info out of nucleus Transcript translated to protein What is the function of tRNA? Correct Answer: Carries aa to ribosome Anticodon pairs with codon on mRNA strand What is the function of rRNA? Correct Answer: part of ribosome structure most abundant RNA coordinated coupling of tRNA to mRNA codons Feedback inhibition Correct Answer: Product of pathway is noncompetitive inhibitor Binds to allosteric site to slow down rxn b/c too much product Exonucleases Correct Answer: Degrades nucleic acids by removing one terminal nt at a time Cleaves phosphodiester bond at end of chain 5' -- 3' and 3' -- 5' Endonucleases (Prok) Correct Answer: Restriction enzymes Cleaves phoshpodiester bonds w/i poly-nt chain Recognition site is palindromic sequence Types I-V ORI sites Correct Answer: nt sequence where replication is initiated Topoisomerase I Correct Answer: Induces ss breaks Remove DNA supercoils during TXN and DNA replication; for strand breakage during recombination; for chr condensation; and to disentangle intertwined DNA during mitosis topoisomerase II Correct Answer: cuts both strands of one DNA double helix, passes another unbroken DNA helix through it, and then reanneals the cut strands Gyrase (topoisomerase II) Correct Answer: Unwinds supercoiling caused by unwinding at the rep fork by introducing DSBs