ASCP RNA & DNA Questions and Verified solution 2023/2024

ASCP RNA & DNA Questions and Verified solution 2023/2024 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 Helicase - correct answer Breaks H-bonds of double helix at the replication fork Primase - correct answer DNApol α (DNA dep RNA pol) adds short segments of complementary RNA to ssDNA template (primers), serves as starting points for replication single-strand DNA binding proteins (SSBPs) - correct answer Binds ssDNA and prevents it from re-annealing during TXN, replication, repair, and recombination Okazaki fragments - correct answer Short fragments of DNA synthesized by DNApol δ using the lagging strand (3'-5') as a template Ligase - correct answer Closes gaps in DNA Catalyzes phosphodiester bond between 3'OH and 5'P What are the steps in DNA replication? - correct answer 1. Initiate 2. Elongate 3. Terminate Telomeres - correct answer Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation RNA polymerase - correct answer DNA dependent RNApol Transcribes DNA template to RNA (3'--5'; anti-parallel) Splicesomes - correct answer Complex of snRNPs Removes introns from pre-mRNA and splices exons together Enhancers - correct answer Short regions of DNA that bind proteins (TXN factors) that enhance TXN of a gene Poly-A tail - correct answer Prevents mRNA from being degraded in cytoplasm 100-250 A's at 3' end 5' cap - correct answer 5'-5' pyrophosphate bridge to a methylated G added to 5' end of a mRNA Protects against degradation and as a recognition signal for TLN apparatus aminoacyl tRNA - correct answer tRNAs that carry amino acids Ribosomes - correct answer Where TLN occurs Prok: 30s and 50s Euk: 40s and 60s Catalyzes peptide bond between a.a.'s