final exam

The goal of sterilization in microbiology is to remove all microorganisms, making an item absolutely free of microbes, endospores, and viruses.

Pasteurization is a brief heat treatment used to reduce organisms causing food spoilage and to protect heat-sensitive products.

<p>Bacteriostatic refers to inhibiting, but not killing, microbes.</p> Signup and view all the answers

<p>D-value is the time required to kill 90% of a microbial population at a specific temperature.</p> Signup and view all the answers

<p>Number of microbes</p> Signup and view all the answers

<p>Disinfection removes pathogens from inanimate objects, while antisepsis removes pathogens from living tissues.</p> Signup and view all the answers

<p>They inhibit the growth of Gram-positive bacteria, making it selective for Gram-negative organisms.</p> Signup and view all the answers

<p>Such a medium inhibits certain microorganisms while allowing others to grow and differentiates between them based on specific biochemical reactions.</p> Signup and view all the answers

<p>It is used for isolating osmotolerant bacteria and differentiating those that ferment mannitol.</p> Signup and view all the answers

<p>Sterilization removes all microbial life, while sanitization reduces microbial counts to safe levels on surfaces and utensils.</p> Signup and view all the answers

<p>Commercial sterilization specifically targets the destruction of Clostridium botulinum endospores in canned goods.</p> Signup and view all the answers

<p>Filtration physically removes microorganisms from air or liquids.</p> Signup and view all the answers

<p>It describes how a fixed proportion of microbial cells die per unit of time during treatment.</p> Signup and view all the answers

<p>Blood agar helps identify bacteria based on their hemolytic activity.</p> Signup and view all the answers

<p>pH indicators detect metabolic byproducts, such as acid production, and change color accordingly.</p> Signup and view all the answers

<p>Its lactose and pH indicator allow differentiation between lactose-fermenting and non-fermenting bacteria.</p> Signup and view all the answers

<p>Heat sterilization (autoclaving)</p> Signup and view all the answers

<p>It does not achieve sterilization but only reduces the number of pathogens and spoilage organisms.</p> Signup and view all the answers

<p>Irradiation damages microbial DNA, preventing replication and survival.</p> Signup and view all the answers

<p>It is a selective medium used to isolate Neisseria gonorrhoeae by inhibiting contaminating organisms.</p> Signup and view all the answers

<p>Heat sterilization kills microorganisms by denaturing their proteins and disrupting their membranes.</p> Signup and view all the answers

<p>Disinfectants are used on inanimate surfaces, while antiseptics are used on living tissues.</p> Signup and view all the answers

<p>Biofilms are structured microbial communities attached to surfaces, often making microbes more resistant to control methods.</p> Signup and view all the answers

<p>HTST effectively kills pathogens while preserving milk's nutritional and sensory qualities.</p> Signup and view all the answers

<p>A biocide kills microorganisms, whereas a bacteriostatic agent inhibits their growth without killing them.</p> Signup and view all the answers

<p>A chemically defined medium has a known, precise chemical composition, allowing for controlled experimental conditions.</p> Signup and view all the answers

<p>It physically traps microorganisms within the pores of a filter, effectively removing them from liquids or air.</p> Signup and view all the answers

<p>UV light damages microbial DNA, preventing replication and leading to cell death.</p> Signup and view all the answers

<p>Organic matter can shield microbes from disinfectants, reducing their effectiveness.</p> Signup and view all the answers

<p>Use a combination of autoclaving surgical tools, UV light for surface disinfection, and chemical sterilants for heat-sensitive equipment.</p> Signup and view all the answers

<p>Organic matter can block UV light, preventing it from reaching microorganisms effectively.</p> Signup and view all the answers

<p>Moist heat is more reliable for killing all microbes, including spores, but may damage heat-sensitive devices, where chemical disinfectants would be better suited.</p> Signup and view all the answers

<p>Use MacConkey agar to differentiate lactose-fermenting Gram-negative bacteria from other contaminants.</p> Signup and view all the answers

<p>Combine chemical disinfectants like chlorine with mechanical removal methods (scrubbing or ultrasonic cleaning) to disrupt biofilms.</p> Signup and view all the answers

<p>The higher viscosity of cream reduces heat penetration, requiring longer treatment times.</p> Signup and view all the answers

<p>Benefits include sterilization of heat-sensitive tools, but risks involve toxicity, flammability, and requiring special equipment.</p> Signup and view all the answers

<p>Calculate the time needed to achieve a specific microbial reduction at a given temperature to ensure safety while preserving food quality.</p> Signup and view all the answers

<p>Include daily cleaning with chemical disinfectants, weekly heat sterilization of machinery, and regular microbial testing.</p> Signup and view all the answers

<p>Biofilms provide a physical barrier and a supportive environment, reducing disinfectant penetration and effectiveness.</p> Signup and view all the answers

<p>Autoclaving is cost-effective and widely used but unsuitable for heat-sensitive materials, while gamma irradiation is better for packaged and heat-sensitive items.</p> Signup and view all the answers

<p>Use sterile packaging and seal them in airtight containers to prevent microbial contamination.</p> Signup and view all the answers

<p>Observe hemolysis patterns to identify pathogens like Streptococcus pyogenes based on their ability to lyse red blood cells.</p> Signup and view all the answers

<p>Solid or dense foods can prevent uniform heat penetration, leaving some microbes unaffected.</p> Signup and view all the answers

<p>Disinfectants are practical and easy to use but less reliable than heat sterilization for complete microbial elimination.</p> Signup and view all the answers

<p>Use a combination of chemical disinfectants and UV sterilization, ensuring no residues remain on bottles.</p> Signup and view all the answers

<p>Use strict sterilization protocols, limit antibiotic use, and monitor for resistant strains regularly.</p> Signup and view all the answers

<p>Organic residues can insulate microbes from heat and prevent complete sterilization.</p> Signup and view all the answers

<p>UV light leaves no chemical residue but doesn't provide residual protection like ozone does.</p> Signup and view all the answers

<p>Use portable autoclaves or chemical sterilants for heat-sensitive equipment and prioritize single-use sterile items when possible.</p> Signup and view all the answers

<p>Physical methods (e.g., heat, irradiation, filtration) and chemical methods (e.g., antimicrobial chemicals)</p> Signup and view all the answers

<p>Bacteriostatic refers to inhibiting, but not killing, microbes.</p> Signup and view all the answers

<p>The number of microbes, environment (organic matter, temperature, biofilms), time of exposure, and microbial characteristics</p> Signup and view all the answers

<p>It describes how a fixed proportion of microbial cells die per unit of time during treatment.</p> Signup and view all the answers

<p>Heat sterilization (autoclaving) and chemical sterilization (ethylene oxide gas)</p> Signup and view all the answers

<p>Use a combination of autoclaving surgical tools, UV light for surface disinfection, and chemical sterilants for heat-sensitive equipment.</p> Signup and view all the answers

<p>Organic matter can block UV light, preventing it from reaching microorganisms effectively.</p> Signup and view all the answers

<p>Moist heat is more reliable for killing all microbes, including spores, but may damage heat-sensitive devices, where chemical disinfectants would be better suited.</p> Signup and view all the answers

<p>Use MacConkey agar to differentiate lactose-fermenting Gram-negative bacteria from other contaminants.</p> Signup and view all the answers

<p>Combine chemical disinfectants like chlorine with mechanical removal methods (scrubbing or ultrasonic cleaning) to disrupt biofilms.</p> Signup and view all the answers

<p>The higher viscosity of cream reduces heat penetration, requiring longer treatment times.</p> Signup and view all the answers

<p>Benefits include sterilization of heat-sensitive tools, but risks involve toxicity, flammability, and requiring special equipment.</p> Signup and view all the answers

<p>Calculate the time needed to achieve a specific microbial reduction at a given temperature to ensure safety while preserving food quality.</p> Signup and view all the answers

<p>Include daily cleaning with chemical disinfectants, weekly heat sterilization of machinery, and regular microbial testing.</p> Signup and view all the answers

<p>Biofilms provide a physical barrier and a supportive environment, reducing disinfectant penetration and effectiveness.</p> Signup and view all the answers

<p>Autoclaving is cost-effective and widely used but unsuitable for heat-sensitive materials, while gamma irradiation is better for packaged and heat-sensitive items.</p> Signup and view all the answers

<p>Use sterile packaging and seal them in airtight containers to prevent microbial contamination.</p> Signup and view all the answers

<p>Observe hemolysis patterns to identify pathogens like Streptococcus pyogenes based on their ability to lyse red blood cells.</p> Signup and view all the answers

<p>Solid or dense foods can prevent uniform heat penetration, leaving some microbes unaffected.</p> Signup and view all the answers

<p>Disinfectants are practical and easy to use but less reliable than heat sterilization for complete microbial elimination.</p> Signup and view all the answers

<p>Use a combination of chemical disinfectants and UV sterilization, ensuring no residues remain on bottles.</p> Signup and view all the answers

<p>Use strict sterilization protocols, limit antibiotic use, and monitor for resistant strains regularly.</p> Signup and view all the answers

<p>Organic residues can insulate microbes from heat and prevent complete sterilization.</p> Signup and view all the answers

<p>UV light leaves no chemical residue but doesn't provide residual protection like ozone does.</p> Signup and view all the answers

<p>Use portable autoclaves or chemical sterilants for heat-sensitive equipment and prioritize single-use sterile items when possible.</p> Signup and view all the answers

<p>A virus can infect any type of cell, including bacteria, while a bacteriophage is a type of virus that specifically infects bacteria.</p> Signup and view all the answers

<p>The lysogenic cycle allows the viral DNA to integrate into the host cell's genome, becoming a prophage. This allows the virus to replicate along with the host DNA.</p> Signup and view all the answers

<p>A genetic switch determines whether a temperate phage will follow the lytic or lysogenic lifecycle. This decision depends on factors like the host's health and environmental stimuli.</p> Signup and view all the answers

<p>Attachment = The phage attaches to the bacterial cell through tail fibers. Penetration = The bacteriophage injects its DNA into the host cell using lysozyme. Maturation = The phage's DNA is incorporated and replicated within the host cell. Biosynthesis = New phage particles are assembled inside the host cell. Release = The phage lysozyme degrades the bacterial cell wall, releasing the newly formed bacteriophages.</p> Signup and view all the answers

<p>Attachment = Attachment of viruses to the cell membrane, often through a specific receptor. Penetration = Entry of the virus into the host cell through endocytosis or fusion. Uncoating = Removal of the viral capsid, releasing the viral genome into the cytoplasm. Biosynthesis = Replication of viral nucleic acid (DNA or RNA) and synthesis of viral proteins using host cell machinery. Maturation = Assembly of viral nucleic acid and proteins into new viral particles. Release = Release of newly formed viral particles from the host cell, usually through budding or lysis.</p> Signup and view all the answers

<p>Bacteriophages typically inject only their DNA into the host cell, while animal viruses generally enter the host cell as a whole. Bacteriophages often cause lysis of the host cell during release, while animal viruses may use budding for release.</p> Signup and view all the answers

<p>The lytic cycle results in the destruction of the host cell. The virus replicates and produces new viral particles, leading to the lysis of the host cell, releasing the new viruses.</p> Signup and view all the answers

<p>The lysogenic cycle allows for the viral DNA to integrate into the host cell's DNA and replicate along with it. The viral genes are typically repressed, allowing the virus to coexist with the host cell.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Integration involves the incorporation of the phage's DNA into the host cell's genome. This occurs through a specific recombination process involving the phage's attachment site (attP) and the host's attachment site (attB).</p> Signup and view all the answers

<p>Transduction is a method of horizontal gene transfer in bacteria, mediated by bacteriophages. It occurs when a bacteriophage carries bacterial DNA from one host cell to another.</p> Signup and view all the answers

<p>General transduction involves accidental packaging of bacterial DNA fragments into a phage. Specialized transduction occurs when a phage excises itself from the host chromosome carrying a segment of the host DNA, often a specific gene.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>The sigma factor is a protein that helps RNA polymerase recognize and bind to promoter regions, while the Kozack sequence is a specific sequence in mRNA essential for the initiation of protein synthesis.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>The key steps include attachment, penetration, uncoating, biosynthesis, maturation, and release. Viruses bind to the host cell, enter through endocytosis or fusion, release their genetic material, replicate using host cell machinery, assemble new viral particles, and then exit the host cell.</p> Signup and view all the answers

<p>Animal viruses often use endocytosis or membrane fusion, while bacteriophages can penetrate directly through the cell wall.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers