Mutation, Gene Regulation, and Antimicrobial Drugs

Flashcards about Mutation, Gene Regulation, and Antimicrobial Drugs

What is a mutation?

Any permanent alteration in DNA sequence that can be harmful, beneficial, or neutral. For it to be heritable, DNA must be changed and no repair happens.

What are the classes of mutations?

Point mutations/base substitutions, Insertion/Deletion, Frameshift mutation, and Inversion.

List the three types of point mutations.

Silent mutation, Missense mutation, and Nonsense mutation.

What are some causes of mutations?

Mistakes by DNA polymerase, physical agents (cosmic rays, X-rays, UV radiation), and chemical agents (reactive oxygen molecules, acridine orange, mutator strains).

What are some ways to repair DNA?

Base excision repair, Methyl mismatch repair, SOS repair, DNA recombination, Nucleotide excision repair, and Photoreactivation.

How can genes be regulated?

By changing DNA sequence, control of transcription (repressors, activators, alternative sigma factors), translational control, and post-translational control.

What are the promoter and the operon?

Promoter: region where gene is regulated where the activator proteins bind and gene expression takes place. Operon: a set of genes controlled by the same promoter.

What does 'mRNA is polycistronic' mean?

mRNA can code for multiple proteins due to having multiple genes on it, typically in bacteria.

What is vertical gene transfer?

Occurs during reproduction between generations of cells.

What is horizontal gene transfer?

The transfer of genes between cells of the same generation, including transformation, transduction, and conjugation.

What are plasmids?

Mostly circular, double-stranded, extrachromosomal DNA that are self-replicating.

What is induction?

Protein in the presence of inducer binds to activation protein and induced expression of gene. When inducer is absent, it leads to a repression of the gene

How do cells sense and respond to their environment?

Sensing the intracellular environment, global regulators affect expression of many genes, and sensing the extracellular environment using two-component protein phosphorylation relay systems.

What is genetic recombination?

Transfer of genetic material from one bacterial cell to another that alters genetic characteristics of the recipient cell.

What functions do plasmids provide to bacterium (that allows them to survive)?

Direct synthesis of the protein towards the pili, Resistance (R) plasmids carry genes that provide resistance to antimicrobials. Virulence plasmids (neurotoxin) cause disease signs and symptoms, tumor inducing plasmids – cause tumor formation in plants.

What are mobile genetic elements?

Genes that can move on a chromosome to another are called transposable elements, or transposons. They contain a transposase gene that moves the element.

What is transformation?

Importing free DNA from the environment into bacterial cells.

What is transduction?

Gene transfer is mediated by a bacteriophage (bacterial virus) vector.

What is conjugation?

Gene transfer requires contact between donor and recipient cells; larger quantities of DNA are transferred compared to transduction or transformation.

What is gene fusion?

Transposition of genes from one location of the chromosome to another, resulting in the fusion of two genes together.

What is the degree of microbial control?

The degree of microbial control can be evaluated using a microbial death curve to describe the progress and effectiveness of a particular protocol when exposed to a particular microbial control protocol, a fixed percentage of the microbes within the population will die.

What are biosafety levels?

Levels of disease ordered by severity of disease and ease of transmission.

Define Sterilization

Process by which ALL living cells, spores, and viruses are destroyed on an object

Define Disinfection

The killing or removal of DISEASE-PRODUCING organisms from inanimate surfaces; DOES NOT necessarily result in sterilization

Define Antisepsis

Similar to disinfection, but applies to removing pathogens from the surface of LIVING tissues, such as skin

Define sanitation

Consists of reducing the microbial population to safe levels and usually involves cleaning an object as well as disinfection

What are the two categories of antimicrobials?

Cidal agents (kill microbes) and Static agents (inhibit or control growth).

What are factors to select the disinfectant?

Must be fast-acting, effective against all microorganisms, easily penetrate material, easy to prep, inexpensive, and not have an unpleasant odor.

What is a microbial death curve?

A curve that plots the number of surviving microbial cells as a function of exposure time to a particular antimicrobial agent.

What factors influence the speed at which lethal damage accumulates?

Initial population size, population composition, agent concentration or dose, duration of exposure, and presence of organic material (organic load).

Can microbes be controlled without chemicals?

Yes, physical agents are often used to kill microbes or control their growth. Commonly used physical control measures include Temperature extremes, Pressure (usually combined with temp), Filtration, Irradiation

What is the goal of pasteurization?

To kill pathogens without affecting the texture, color, or taste of the product

Name the 3 processes for pasteurization

Low temp and long time (LTLT); High temp, short time (HTST); Ultra high temp (UHT)

What are the basic purposes of cold temps in microbio?

To temper growth and preserve strains.

What is sonication?

It is the use of high-frequency ultrasound waves to disrupt cell structures, leading to cavitation and cell lysis, useful for lysing cells and cleaning instruments.

What does the efficiency of a chemical agent depend upon?

The presence of organic matter, the kinds of organisms present, corrosiveness, stability, odor, and surface tension.

What are key characteristics of Gas Sterilization?

destroys proteins, microbicidal/sporicidal, rapidly penetrates packing materials, including plastic wraps, highly explosive

What are the first antimicrobial drugs?

Compound 606 (Salvarsan), Penicillin, Prontosil, and Sulfanilamide.

What is a chemotherapeutic agent?

Any chemical agent used in medical practice.

What is an antibiotic agent?

A chemical substance made by a microorganism that can inhibit the growth or kill microorganisms.

What is an antimicrobic or antimicrobial agent?

A chemical substance similar to an antibiotic, but may be synthetic.

What is selective toxicity?

Harms microbes but not damaging to the host.

What does spectrum of activity refer to?

No single chemotherapeutic agent affects all microbes; antimicrobial drugs are classified based on the type of organism they affect (narrow, broad)

How do superinfections develop?

Normal microbiota are killed by broad-spectrum antibiotics, allowing drug-resistant pathogens to proliferate.

What is the minimal inhibitory concentration (MIC)?

The lowest concentration of the drug that will prevent the growth of an organism.

What is the Kirby-Bauer disk susceptibility test?

A test that uses disks impregnated with different antibiotics placed on a bacterial lawn to determine drug susceptibility based on zones of inhibition.

What are the attributes of an ideal antimicrobial

Solubility in Body fluids, Selective toxicity, Toxicity not easily altered, Non-allergenic, Stability, Resistance by microorganisms not easily acquired, Long shelf-life, Reasonable cost

What is the chemotherapeutic index?

The ratio of the toxic dose to the therapeutic dose; the higher the index, the safer the drug.

What are synergism and antagonism?

Synergistic drugs work better when combined, while antagonistic drugs interfere with each other and diminish effectiveness.

Which antibiotics target the bacterial membrane?

Polymyxin, Tyrocidin, and Platensimycin

How do antibiotics work?

By disturbing enzymes or structures unique to the target cell, including cell wall synthesis, cell membrane integrity, DNA synthesis, RNA synthesis, protein synthesis, and metabolism.

Which antibiotics target the cell wall?

Penicillins and Cephalosporins

What mechanisms do microbes develop for drug resistance?

Drug modification or inactivation, Blocked penetration, Efflux pumps, Target modification, Target overproduction, Enzymatic bypass, Target mimicry.

What are the Antiviral agents that prevent virus uncoating or release?

Amantadine, Oseltamivir (Tamiflu) and Zanamivir (Relenza)

Nucleoside and NonNucleoside reverse transcriptase inhibitors

They both inhibit or stall viral particles.

What fungal infections are target by Anti-fungal agents?

Polyenes, Azoles, Allymides, Echinocandins, Griseofulvin, Flucytosine

List the ways to treat Anti-parasitic Infections

Antiprotozoal agents and Antihelminthic agents

Differentiate the Sign and Symptom of disease

Sign: Objective and measurable Symptoms: Subjective