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Microbio lab middie
| Question | Answer |
|---|---|
| bacteria culture | pinpoint colonies that increase in size over time |
| bacteria colony | a cluster of closely packed cells that originates from a single cell |
| Fomites | animate and inanimate sources that collect microorganisms |
| Turbidity | The term for being cloudy in appearance. |
| compound microscope | A magnifying instrument that uses two types of lenses to magnify an object with different zoom levels of magnification |
| simple microscope | magnifying instrument that uses only one lens to magnify objects |
| Parfocal | the ability of a microscope to stay relatively in focus as the user switches among the objectives |
| Resolving power | the smallest detail that a microscope can resolve when imaging a specimen |
| Why is oil used with the 100X objective | to eliminate any air gaps and loss of light due to refraction |
| Resolution | The smallest distance between two points on a specimen that can still be distinguished as two separate entities |
| Resolving Power | The ability of a lens to resolve two independent points as discrete entities. It is dependent on the wavelength (λ) of light used |
| Par Focal | The capacity of an instrument to maintain focus regardless of the magnification used |
| What are the 2 factors that enhance resolution | numerical aperture wavelength of light used |
| Name four positive stains | MRSA Strep Staph bacillus |
| Name two negatives stains | E colli Neisseria |
| Aseptic Techniques | Procedures that reduce the risk of unwanted microbes present in air, bodies, and other lab equipment from contaminating our cultures or infecting us |
| Sterile | The point where no microbial forms are present including endospores and viruses |
| Streak for Isolation | A technique for isolating colonies to generate pure culture of bacteria; involves successive streaking to spread a few cells in the inoculum over an agar plate surface |
| Subculturing | The transfer of microorganisms from one medium to another to prepare fresh microbial cultures |
| Antibiotics | compounds that target bacteria |
| bactericidal | a substance which kills bacteria |
| bacteriostatic | biological or chemical agent that stops bacteria from reproducing |
| How can you tell whether the test microorganism was sensitive or resistant to the chemotherapeutic agent? | Sensitive-zone of inhibition resistant-no zone of inhibtion |
| What does the zone of inhibition represent | zero colonies |
| State the factors that influence the size of the zone of inhibition | potency, not right type of agar, concentration |
| Simple Stain | A basic stain that is used to give color to bacterial cells. |
| Differential stain | A staining procedure or media that allows one to distinguish types of bacteria based on how they stain or grow |
| Biological stains | improve the visibility of particular structures, cells, or tissues when viewed via a microscope |
| Negative Stain | A stain that is used to color the background of a slide leaving the bacterial cells colorless |
| Describe the morphology and cellular arrangement of two species of bacteria. | Staphylococcus epidermidi - Gram-positive cocci (round) arranged in tetrads and grape-like clusters. Serratia marcescens - Gram-negative, rod-shaped, clustered. |
| State two reasons why a negative stain is used. | To observe bacterial that have external features that may be either impermeable to dyes or may get distorted by heat (ex. capsules). Cells less shriveled, more natural. |
| Discuss the implications of capsules in bacterial diseases. | The capsule is a polysaccharide outer cover that some bacteria have. - It is used for attachment to the host cell. It enhances the bacteria's ability to cause disease because it can protect cells from engulfment by eukaryotic cells, such as macrophages. |
| As you rush to be in time for the Microbiology lab, you accidentally spill coffee on your lab coat and the white fabric gets stained. Is this a biological stain or simply a compound that is capable of imparting color to the fabric? Explain your reasoning. | Simply a compound capable of imparting color to the fabric - coffee does not contain an autochrome group which converts the property of ionization to the chromogen, enabling it to form salts and bind to fibers or tissues. |
| List and describe the rationale for the steps required to prepare a bacterial smear. | Thin and uniform smear - to avoid clumping and make it easier to observe. Air dry - remove excess water Heat fix - to secure microbes to slide and kill unwanted contaminants Apply stain - to make the microbes visible |
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