VBS 2032 BACTERIAL GENETICS QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026

VBS 2032 BACTERIAL GENETICS QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026 Bacterial classification - Answers Classified by genus and species nomenclature similar to higher organisms but classification is difficult because bacteria have huge diversity with thousands of strains (ex: Salmonella enterica has over 2,000 strains) Mutation - Answers A change in DNA sequence that can be harmful, harmless, or rarely beneficial Fitness - Answers How well a bacterium is able to reproduce Harmful mutation - Answers A mutation that is lethal or decreases bacterial fitness Harmless mutation - Answers A DNA change that does not change the protein or changes it so slightly that the function remains the same Helpful mutation - Answers Rare mutation that improves survival such as antibiotic resistance when the drug is present Antibiotic resistance mutation - Answers Mutation that allows bacteria to survive antibiotics such as streptomycin or rifampin but may reduce fitness when the drug is absent Base substitution - Answers Most common mutation where one base is replaced by another resulting in silent, missense, or nonsense mutations Silent mutation - Answers A base substitution where the codon still codes for the same amino acid so the protein is unchanged Missense mutation - Answers A base substitution that results in a codon coding for a different amino acid which may still allow partial or full protein function Nonsense mutation - Answers A base substitution that changes a codon into a stop codon producing a shortened nonfunctional protein Insertion or deletion mutation - Answers Bases are added or removed causing a frameshift so the entire reading frame and resulting protein changes Frameshift mutation - Answers Mutation caused by insertion or deletion of bases that changes the reading frame and often produces a nonfunctional protein DNA proofreading - Answers DNA polymerase checks newly synthesized DNA and removes incorrect bases before adding the correct one Mismatch repair - Answers Repair system that scans DNA for mismatched bases, removes a section of DNA, and allows DNA polymerase to rebuild the correct sequence Repair of modified nucleobases - Answers Enzymes recognize chemically damaged nucleotides such as oxidized bases and repair them Thymine dimer - Answers UV radiation damage where two thymine bases bond together disrupting DNA replication Photoreactivation - Answers Light dependent repair where an enzyme uses light energy to break thymine dimer bonds Excision repair - Answers Dark repair process where enzymes remove damaged DNA sections and DNA polymerase replaces them Mutation in photoreactivation or excision repair enzymes - Answers Often leads to cancer because UV DNA damage cannot be repaired properly SOS repair - Answers Emergency DNA repair system where the cell stops dividing and repairs severe DNA damage caused by chemicals or UV light Vertical gene transfer - Answers DNA is copied and passed from parent cell to daughter cells during binary fission Horizontal gene transfer - Answers Transfer of DNA between bacteria by transformation, conjugation, or transduction Transformation - Answers Uptake of free DNA from dead bacteria by a living bacterium Conjugation - Answers Transfer of DNA between bacteria through direct cell to cell contact using a specialized pilus Transduction - Answers Transfer of bacterial DNA from one bacterium to another via bacteriophages Frederick Griffith transformation experiment - Answers Demonstrated transformation using rough and smooth strains of Streptococcus pneumoniae Smooth strain of Streptococcus pneumoniae - Answers Encapsulated bacteria that cause disease because the capsule acts as a virulence factor Capsule virulence factor - Answers Protects bacteria from immune cells by preventing phagocytosis Rough strain of Streptococcus pneumoniae - Answers Nonencapsulated bacteria that do not cause disease