VBS 2032 EXAM II QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026

VBS 2032 EXAM II QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026 Mutations - Answers Permanent alteration in the DNA sequence of a microorganism. It may be lethal. Fitness - Answers How well bacteria can reproduce. Affected by mutations. Base substitutions - Answers Genetic mutation where one base is incorrectly exchanged for another during DNA replication. Silent mutation - Answers Redundant mutation that does not change the protein. Missense mutation - Answers Most likely results in a protein that is changed, can still be understood Nonsense mutation - Answers Unlikely to function properly and results in a stop codon. Additions or deletions - Answers Change the reading frame of the DNA sequence. Reading frame - Answers A way of dividing a sequence of nucleotides in DNA or RNA into a series of consecutive, non-overlapping three-base units called codons. Proofreading - Answers Process by which DNA polymerase corrects errors during DNA replication. Mismatch repair - Answers Cellular system that corrects errors in DNA. Vertical gene transfer - Answers Transfer of DNA from parent to offspring during binary fission. Horizontal gene transfer - Answers Transfer of DNA between different bacteria without cell replication. Transformation - Answers Process of taking up free DNA from the environment. Conjugation - Answers Genetic material is transferred from one bacterial cell to another through direct contact. Transduction - Answers DNA is transferred from one bacterium to another by phage. Smooth strains - Answers Variant of bacteria that appear smooth on agar plates and are virulent. Capsules - Answers Produced by smooth strains, helping bacteria evade the host's immune system. Pilus - Answers Hair-like appendage that assists in motility, host attachment, and transfer of genetic material. Resistance genes - Answers Segments of DNA that code for proteins making organisms resistant to specific drugs. VRE - Answers Gram-positive bacteria resistant to antibiotic vancomycin, causing hospital-required infections. MRSA - Answers Gram-positive bacteria resistant to many microbial medications including methicillin. VRSA - Answers Gram-positive bacteria that have acquired resistance genes from MRSA through conjugation. Virulence genes - Answers Molecules or traits produced by pathogens that contribute to their ability to cause disease. Bacteriophages - Answers Viruses that infect and replicate within bacteria. Lysogeny - Answers Stage of dormancy where a temperate bacteriophage integrates its genome into the host's chromosome. Temperate phage - Answers Phage that can integrate into the bacterial chromosome and remain indefinitely. Lytic/virulent phage - Answers Bacteriophage that replicates exclusively through the lytic cycle, causing host cell death. Prophage - Answers Dormant, integrated form of a bacteriophage within the host bacterial genome. Restriction-modification systems - Answers Bacterial enzymes that recognize and degrade foreign phage DNA. CRISPR - Answers Natural bacterial defense mechanism and revolutionary gene-editing technology. Plasmid - Answers Replicon that is independent of the chromosome and generally encodes non-essential genetic information. Antibiotic - Answers Low molecular weight substance produced by a microorganism that inhibits or kills other microorganisms. Antimicrobial drug - Answers Any substance that inhibits or kills microorganisms without harming the host. Paul Erlich - Answers Known as the 'father of chemotherapy' for discovering arsenic compounds to treat syphilis. Gerhard Domagk - Answers Discovered the first sulfa drug (Prontosil) to treat Streptococcus. Alexander Fleming - Answers Identified Penicillium mold that excretes a compound toxic to Staphylococcus. Selman Waksman - Answers Discovered many antibiotics produced by soil bacteria, including Streptomycin. Kirby-Bauer - Answers Disc diffusion assay, each disc contains a different drug, if it is sensitive, bacteria doesn't grow there, no inhibition and resistance is high. E-test - Answers Measures the minimum inhibitory concentration (MIC). Therapeutic window - Answers Concentration of drug that inhibits the microbe without harming the host. Most drugs exhibit adverse effects at high concentrations. AMR genes - Answers 1. Drugs can't enter the cell - outer membrane changes so they cannot get in, 2. drugs are pumped out of the cell (efflux pumps), 3. enzymes inactivate drug (B-lactamases degrade various B-lactam drugs), 4. host target is mutated (changes shape) so that drugs cannot bind. Types of AMR - Answers Intrinsic: quality that doesn't change, ex. Mycoplasma and B-lactams; Physiological: biofilms produce EPS, persisters (non-dividing state), altered physiology, more temporary; Genetic change: spontaneous mutations, horizontal gene transfer, need enough antibiotic at a high level for short time. Co-selection - Answers One antimicrobial agent, such as heavy metal, selects for resistance to a different agent, like an antibiotic. Resistance development time - Answers Not very long, depending how much you use it, sometimes 2-3 years. Urgent threats - Answers Acinetobacter - hospital required infection, hard to get rid of; Candida Auris - fungus, assisted nursing; Clostridioides Difficile - C. diff; Enterobacteriaceae - E. coli; Neisseria Gonorrhoeae - gonorrhea. C. diff - Answers A bacterium that causes inflammation of the colon (colitis), it is a common cause of antibiotic associated diarrhea, and can lead to severe health problems. Serious threats - Answers Vancomycin-resistant, multidrug-resistant, drug resistant TB, streptococcus pneumoniae. New antibiotic class discoveries - Answers Less than 30 due to high economic costs and low financial returns, and regulatory challenges. AMR spread - Answers Through human contact, animals to humans, environment, soil and water, plasmid with disinfectants, form endospores and persist, travels with staff and they can become carriers. Slow AMR spread - Answers Global surveillance and cooperation, responsibilities of physicians and healthcare workers, increase efforts to identify cause of infection, only prescribe antimicrobials when appropriate. Covid-19 PCR tests - Answers Reverse transcribing the virus's RNA into DNA, then repeatedly amplifying specific viral DNA sequences using primers and enzymes to create millions of copies. Restriction enzymes - Answers Enzymes that recognize specific sequences of DNA (palindrome), bind, and cut it. Isolated from bacteria which make them to protect themselves. Use of restriction enzymes - Answers To precisely cut DNA at specific nucleotide sequences, creating sticky or blunt ends. Discovery of restriction enzymes - Answers Werner Arber predicted existence, then Daniel Nathans and Hamilton Smith isolated and demonstrated their use. Structure of DNA - Answers Double helix held together by base pairs, base pairs held together by sugar-phosphate backbone. Dideoxynucleotides - Answers Synthetic DNA building blocks that stop DNA strand elongation during DNA synthesis. Act as chain terminators. Frederick Sanger - Answers Figured out a way for DNA sequencing using dideoxynucleotides. Chain terminators - Answers Prevent a growing DNA strand from extending further by lacking the necessary 3' hydroxyl group to form a phosphodiester bond. Sanger sequencing - Answers Determines the exact order of nucleotide bases in a DNA fragment by creating DNA fragments of varying lengths through random incorporation of fluorescently labeled, chain terminating deoxynucleotides. Requirements for DNA replication - Answers Buffer, template DNA, DNA polymerase, dNTPS, primer. Fluorescent dyes - Answers ddNTPS are labeled with this. Absorb light at one wavelength and emit it at a longer wavelength. Electrophoresis - Answers Many different size fragments can be separated on a gel. DNA sequence - Answers A specific order of nucleotide bases Adenine, Guanine, Cytosine, Thymine that make up a DNA molecule, functioning as the genetic instructions for an organism. PCR - Answers Polymerase chain reaction, amplifies (copies) specific pieces of DNA using primers, nucleotides and DNA polymerase from thermophilic bacterium.