VT BIOL 2604 (SEYLER) EXAM 4 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

VT BIOL 2604 (SEYLER) EXAM 4 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Molecular Basis of Mutation - Answers Spontaneous or Induced Arise because of changes in the base sequence of the nucleic acid of an organism's genome. point mutation - Answers change in a single base pair and can lead to a single amino acid change in a polypeptide or to no change at all Deletion - Answers A change to a chromosome in which a fragment of the chromosome is removed. Insertion - Answers A mutation involving the addition of one or more nucleotide pairs to a gene. frameshift mutation - Answers mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide mutation rates - Answers •Mutations can occur spontaneously during nucleic acid replication. •Rates of 10-7 to 10-11 per base pair is generally seen. •Although RNA and DNA polymerases make errors at about the same rate, RNA genomes typically accumulate mutations at much higher frequencies than DNA genomes. thymine analog - Answers 5-bromouracil adenine analog - Answers 2-amino purine DNA repair - Answers • Some DNA damage can lead to cell death if not repaired. A complex cellular mechanism called the SOS regulatory system is activated as a result of some types of DNA damage and initiates a number of DNA repair processes, both error-prone and high-fidelity. Homologous recombination - Answers arises when closely related DNA sequences from two distinct genetic elements are combined in a single element Ames test - Answers • Histidine auxotrophs are plated on a medium with no histidine. • Spontaneous mutants arise that have regained the ability to make their own histidine. • Paper disks with chemicals that increase the mutation rate allow the formation of more colonies. • Mutagenesis is linked to tetarogenesis (carcinogenesis) Transformation - Answers uptake of "naked" DNA directly from the environment Transduction - Answers phage-mediated transfer of DNA Conjugation - Answers transfer via cell-to-cell contact; pilus mediated Discovery of Transformation - Answers Griffith's experiment with pneumococcal infections in mice Types of transformation - Answers with DNA Fragments with Plasmid transformation with DNA fragments - Answers uptake of DNA integration by nonreciporacal recombination: stable transformation degradation: unsuccessful transformation generalized transduction - Answers binding destruction of host dna synthesis of virus DNA and coat proteins virus capsid synthesis and virus assembly lysis of cell with release of phage particles lysogenic pathway - Answers integrate its genome into the host, replicating with the bacterium lytic pathway - Answers viruses replicate new virions lifecycle of temperate virus - Answers attachment injection lysogenic/lytic pathway specialized transduction - Answers specific bacterial genes are packaged inside a phage and transferred to a recipient cell conjugation steps - Answers pilus retracts cell pair stabilized F plasmid nicked on one strand transfer of one strand from F+ to F- simultaneous F+ replication synthesis of complementary strand in F- completion of DNA transfer and synthesis cells seperate Prokaryotic Transcription - Answers • Single form of RNA polymerase • Introns are rare • Polycistronic messages • Little RNA processing (especially mRNA) • Few transcription initiation factors • Transcription is cytoplasmic Eurkaryotic Transcription - Answers • Multiple forms of RNA polymerase • Introns are common • Monocistronic messages • Extensive RNA processing • Multiple transcription initiation factors • Transcription is nuclear mechanisms of regulating gene product activity - Answers control of enzyme activity-no product translational control- no enzyme synthesis transcriptional control- no mRNA synthesis genetic palindrome - Answers DNA sequences in which regions are repeated and inverted relative to each other. features of DNA binding proteins - Answers domain containing protein-protein contacts DNA binding domain fits in major groove genetic palindromes restriction modification system - Answers A system used by bacteria to cleave exogenous DNA at specific sites using a restriction endonuclease, and protect the sites on its own DNA by methylation. positive control - Answers requires an activator protein to stimulate transcription at the operon negative control - Answers repressor protein inhibits transcription at the operon catabolite repression - Answers presence of glucose inhibits transcription of sugar metabolism genes positive control by CAP CAP must bind to cAMP for activation glucose & cAMP=inversely related higher glucose=lower cAMP and lower transcription Attenuation - Answers termination of transcription prior to structura genes result of hairpin formation high tryptophan: ribosome speeds thru reg 1 and to reg 2 prevents 2&3 binding form attenuator-stops transcription