BIO 400 Exam 1 A+ Pass Verified 2025 Brand New!!

BIO 400 Exam 1 A+ Pass Verified 2025 Brand New!! Which RNA carries genetic information for protein synthesis? - Answer- mRNA. What are the main types of RNA and their functions? - Answer- mRNA = coding info, rRNA = ribosome structure/catalysis, tRNA = amino acid transfer, snRNA = splicing, miRNA/siRNA = regulation, lncRNA = epigenetic regulation. Which base pairs are strongest in DNA? - Answer- G≡C (3 hydrogen bonds, more stable). What stabilizes DNA besides H-bonds? - Answer- Base stacking via van der Waals interactions. What are the major and minor grooves in DNA? - Answer- Sites where proteins (e.g., transcription factors) interact with DNA. Which enzyme unwinds DNA? - Answer- Helicase. Which enzyme synthesizes DNA? - Answer- DNA polymerase. What distinguishes a nucleotide from a nucleoside? - Answer- Nucleotide = nitrogenous base + sugar + phosphate group; Nucleoside = base + sugar, no phosphate. What is the template strand in transcription? - Answer- The antisense strand read by RNA polymerase 3′→5′ to synthesize RNA 5′→3′. What is the coding strand? - Answer- It has the same sequence as the RNA transcript (except U replaces T). What is the direction of DNA synthesis? - Answer- 5′→3′, adding nucleotides to the 3′-OH end. What are Okazaki fragments? - Answer- Short DNA synthesized on the lagging strand. What enzyme seals nicks between Okazaki fragments? - Answer- DNA ligase. How does DNA polymerase proofread? - Answer- 3′→5′ exonuclease activity. Which factor binds the TATA box in eukaryotes? - Answer- TFIID. What is the Shine-Dalgarno sequence? - Answer- Prokaryotic ribosome-binding site upstream of start codon. What is the Pribnow box? - Answer- Bacterial promoter (-10, TATAAT). What is the Hogness box? - Answer- Eukaryotic TATA box at ~-25 upstream. What is the CAT box? - Answer- Eukaryotic promoter element around -75 (CATAAT). What is the GC box? - Answer- Upstream eukaryotic promoter element with GC-rich repeats. Which initiator amino acid is used in prokaryotes? - Answer- N-formylmethionine (fMet). Which initiator amino acid is used in eukaryotes? - Answer- Methionine. What post-transcriptional modifications occur in eukaryotic mRNA? - Answer- 5′ capping, splicing, and 3′ polyadenylation. What does polycistronic mean? - Answer- One mRNA encodes multiple proteins (common in prokaryotes). What does monocistronic mean? - Answer- One mRNA encodes a single protein (common in eukaryotes). What is an operon? - Answer- Cluster of genes under one promoter/operator in prokaryotes. How do repressors regulate transcription? - Answer- Bind operator to block RNA polymerase. How do inducers work? - Answer- Bind repressors to release them and allow transcription. What do activators do? - Answer- Enhance RNA polymerase binding to promoters. What are sigma factors? - Answer- Guide bacterial RNA polymerase to promoters. What is recombinant DNA? - Answer- DNA formed by combining DNA from different sources. What is cloning? - Answer- Producing identical copies of DNA fragments in host organisms. What does DNA ligase do? - Answer- Joins DNA fragments by forming phosphodiester bonds.