micro quiz part 222

Contamination Accidental introduction of unwanted microorganisms. Inoculation Intentional introduction of microbes into a culture. Deep media Contains the highest percentage of agar, solidifying it. Agar deep Used to study bacterial motility and oxygen requirements. Aseptically inoculate Use an inoculating needle to stab agar deep. Oxygen requirements Test for aerobic vs. anaerobic bacteria. P1000 micropipette Set at 68 uL when displaying '068'. Micropipette conversion 068 uL equals 0.068 mL. Air drying slides Prevents cells from washing off during staining. Heat fixing slides Kills bacteria and attaches them to the slide. Heat as mordant Helps stains penetrate tough cell structures. Acid alcohol in Gram stain Stronger decolorizer, may cause Gram-negative appearance. Negative stain Preserves natural shape without heat fixing. Sabouraud Dextrose agar Selective for fungi due to low pH. SabDex characteristics Low pH and high sugar content for fungi growth. TSA agar Supports a wide variety of bacteria. TSA media category General-purpose, non-selective media. Aseptic technique goals Prevent contamination and protect from harmful microbes. Diaphragm (microscope) Controls light passing through the specimen. Coarse focus knob Used with the 10X low power objective lens. Total magnification At 10X objective lens = 100X magnification. Heat fixing consequences Forgetting may wash away bacteria, no visible cells. Heat fixing before air drying May distort or burst bacteria due to moisture. Gram stain steps Crystal Violet → Iodine → Ethanol → Safranin. Decolorizer purpose Removes primary stain from Gram-negative bacteria. Strongest decolorizer Acid alcohol is the strongest used in lab. Stains needing heat mordant Endospore and Acid-fast stains penetrate tough structures.