Untitled Flashcards Set
Genetics – Day 9
Bacterial Operon Parts:
Promoter: Binds RNA polymerase for transcription.
Operator: Repressor/activator binding site, regulates gene expression.
Structural Genes: Encode enzymes/proteins involved in metabolic pathways.
Regulatory Gene: Produces repressor/activator proteins that regulate transcription.
Inducible vs. Repressible Operons:
Inducible Operon (lac operon): Normally off, activated by an inducer (e.g., lactose).
Repressible Operon (trp operon): Normally on, deactivated by the end product (e.g., tryptophan).
DNA to mRNA (Transcription):
RNA polymerase synthesizes mRNA using DNA as a template at the promoter.
Bacterial vs. Eukaryotic Genome:
Bacterial: Circular, in the nucleoid region.
Eukaryotic: Linear, in the nucleus, with histone proteins.
Definitions:
Genetics: Study of heredity.
Genome: Full set of genes.
Chromosome: DNA structure carrying genes.
Gene: Unit of heredity coding for a protein.
Genetic Code: Translation of DNA/RNA into proteins.
Genomics: Study of whole genomes.
DNA Replication:
Helicase unwinds, primase adds primers, DNA polymerase replicates, ligase seals gaps.
Translation:
Codons: mRNA triplets coding for amino acids.
Anticodons: tRNA triplets complementary to codons.
Translation: tRNA brings amino acids to ribosomes to form proteins.
Horizontal Gene Transfer:
Transformation: Uptake of DNA from the environment.
Conjugation: Direct DNA transfer between bacteria via pilus.
Transduction: DNA transfer via bacteriophages.
Conjugation:
F+ × F–: F plasmid transfer from F+ to F– cell.
Hfr × F–: Chromosomal DNA transfer from Hfr to F– cell.
Engineering a Bacterium to Produce Insulin:
Insert the insulin gene into a plasmid, transform bacteria, and culture them to produce insulin.
PCR:
Amplifies DNA by repeating cycles of denaturation, annealing, and extension using DNA polymerase.
Physical and Chemical Control of Microbes – Day 10
Microbial Control Terms:
Sterilization: Kills all microorganisms.
Disinfection: Kills most but not all microorganisms.
Antisepsis: Kills microorganisms on living tissues.
Degerming: Removes microbes by scrubbing.
Sanitization: Reduces microbial load.
Biocide/Germicide: Kills microbes.
Bacteriostasis: Inhibits growth without killing.
Asepsis: Prevention of infection.
Microbial Control Agents:
Disrupt membranes, denature proteins, and damage DNA.
Heat Effectiveness:
Moist heat (boiling, autoclaving) is more effective than dry heat at killing microbes.
Other Microbial Control Methods:
Filtration: Removes microbes.
Low Temperature: Slows growth.
High Pressure: Denatures proteins.
Desiccation: Dehydration prevents growth.
Osmotic Pressure: High salt/sugar concentrations prevent growth.
Disinfection Factors:
Concentration, exposure time, temperature, microbial resistance.
Antisepsis vs. Disinfection:
Antisepsis: For living tissues.
Disinfection: For inanimate surfaces.
Antimicrobial Treatment – Day 11
Ideal Properties of Antimicrobial Drugs:
Selective toxicity, broad-spectrum, non-toxic to host, bactericidal.
Antibiotic Resistance Mechanisms:
Enzyme production (e.g., beta-lactamase), target alteration, efflux pumps.
Antibiotic Actions:
Inhibit cell wall synthesis, protein synthesis, and DNA replication.
Misuse Encouraging Resistance:
Overuse, self-medication, incomplete courses.
Disk-Diffusion Method:
Measures the effectiveness of antibiotics by observing inhibition zones on agar.
Selecting Microbial Control Methods:
Depends on the situation (e.g., sterilization for surgical tools, antiseptics for wounds).
Antibiotic Producers:
Streptomyces (soil bacteria) produce most antibiotics.
Chemotherapy Challenges:
Viral, fungal, protozoan, and helminthic infections are harder to treat due to fewer drug targets and host toxicity.
Definitions:
Spectrum of Activity: Range of organisms an antibiotic can target.
Broad-Spectrum Antibiotics: Effective against a wide range of microbes.
Superinfection: Infection caused by antibiotic-resistant microbes.
Challenges Targeting Viruses:
Viruses use host machinery, making it difficult to target them without harming host cells.
Broad-Spectrum Antibiotics:
Useful but can disrupt normal flora and promote resistance.
Antifungal Drug Actions:
Target ergosterol in cell membranes and cell wall components.
Antiviral Drug Actions:
Inhibit viral enzymes (e.g., reverse transcriptase) and replication.
Antiprotozoan/Antihelminthic Drugs:
Target metabolic processes specific to protozoa and helminths.
Microbial Susceptibility Tests:
Kirby-Bauer Test: Disk diffusion method.
E-Test: Determines the minimum inhibitory concentration (MIC).
Why Bacteria Become Drug Resistant:
Mutations, acquisition of resistance genes, and selective pressure from antibiotics.
MBC vs. MIC:
MIC: Minimum concentration to inhibit growth.
MBC: Minimum concentration to kill 99.9% of bacteria.
Interactions – Day 12
Infectious Disease Classifications:
Pandemic: Global outbreak.
Epidemic: Regional outbreak.
Sign: Objective evidence (e.g., fever).
Symptom: Subjective (e.g., pain).
Microbial Antagonism/Competitive Exclusion:
Normal flora prevent pathogens from colonizing by competing for resources.
Stages of Microbial Disease:
Incubation, Prodromal, Illness, Decline, Convalescence.
Infectious Disease Transmission:
Indirect: Through fomites, droplets, air.
Direct: Physical contact, sexual transmission.
Reservoirs of Disease:
Sources of infection (e.g., humans, animals, environment).
Vectors:
Organisms like mosquitoes that transmit diseases.
Zoonotic Infections:
Diseases transmitted from animals to humans (e.g., rabies, Lyme disease).
Nosocomial Infection Precautions:
Hand hygiene, sterilization, isolation of infected patients.
Portals of Entry:
Skin, mucous membranes, respiratory tract, GI tract.
Gram-Negative Bacteria and Fever:
Endotoxins trigger immune response, leading to fever.
Exotoxins vs. Endotoxins:
Exotoxins: Secreted proteins causing damage.
Endotoxins: Lipid A part of LPS that causes immune response.
Superantigens:
Overstimulate the immune system, causing severe reactions like toxic shock.