MIC 102 Final Exam Questions with Correct Answers

MIC 102 Final Exam Questions with Correct Answers What are the different types of microscopy and staining and when are they used? - Answer-Types of microscopy include: light microscopy- used primarily to get an idea of the form of the bacteria, used in combination with staining to get an idea of Gram positive and Gram negative protein. Green fluorescent is used to observe cell occurrences like binary fission and movement of proteins. Electron microscopy is very detailed at getting an idea of what is occurring inside and outside of the cell (when frozen and cracked in half to see inside) Gram + turns out purple, Gram - is red. Crystal violet essentially gets stuck in the thicker cell wall of Gram +, and iodine is used to bind it, alcohol is used to rinse stain, so if its Gram- it will rinse right out. Safranin is red and used a counter stain so anything left with just red is Gram-. This is used in conjunction with light microscopy. List and outline the differences between Gram positive and Gram negative bacteria, structurally. Explain what their independent structures are functional for. Explain some unique types of outer membranes and archaea cell wall structure, too. - Answer-Gram-: Has thin cell wall with outer membrane. LPS, which acts as an antigen towards the host cell, is protective for the bacteria-- makes it difficult to be consumed by host phagocytosis. Has porins in the outer membrane available as transport channels- allows ionically charged molecules and sugars into the periplasm- unlike the phospholipid bilayer in the inner membrane. Contains lipoproteins which attach the outer membrane to the cell wall. Gram +: has a very thick peptidoglycan cell wall. Both - and + cell walls are made of murein layers. Teichoic acids are in the Gram + wall, which add stability and make the cell wall more rigid and can also be antigenic. Also contains lipo-teichnoic acids- attaches to the inner membrane and holds everything together-goes the furthest in. Both are able to have capsules, which helps for adherence and against desiccation and phagocytosis. Mycoplasma don't have a cell wall. Additionally, acid-fast envelopes are present on mycobacterium, are very waxy and hard to get rid of. Made of waxes called mycolic acids. Archaea have a crystalline S-layer (sometimes bacteria have it). Its attached to the cell wall of the archaea- also made of monomers linked together to make crystalline plate. Helps surface adherence and is protective against other microbes and host defenses (for the archaea). Archaea have ether bond linkage instead of ester (like bacteria), and their cell walls made of isoprenoids which are functioning in place of lipoproteins. Isoprenoids have a different structure from fatty acids that makes them more stable at high temperatures.