Microbiology Exam Questions with 100% Correct Answers | Verified | Updated

Microbiology Exam Questions with 100% Correct Answers | Verified | Updated Peptidoglycan is a polymer of millions of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) sugars based on glucose molecules linked together in long chains cross-braced with four amino acids that link individual polymer chains together in a chain-link fence pattern. Layers of cross-braced NAG and NAM sheets are stacked vertically and held together by proteins with lipid anchors attached to the cell's cytoplasmic membrane to form a scaffold of sugars and proteins that is able to hold the bacterial cell's shape, even in response to extreme osmotic pressures. How would you expect a microbiology student to be able to describe the composition of peptidoglycan? What is the composition of the peptidoglycan layers found in the cell wall of bacteria? - answerShort amino acid chains, NAG, NAM, and some lipid proteins Gram-positive bacterial cell wall - answerTeichoic acids Single lipid bilayer membrane Thick layer of peptidoglycan Gram-negative bacterial cell wall - answerLipopolysaccharides Dual lipid bilayer membrane Thin layer of peptidoglycan Periplasmic space At this point in writing your tutorial, you have to find a way to get across to the students the importance of a cell wall to a bacterium. How do you convey that the bacterial cell will be at the mercy of its environment? The cell wall will need to act as a support mechanism to neutralize the inflow or outflow of water that would alter the shape of the cell. The cell cannot search out for a better place in the environment that has more available water; or if there is water that it has a high enough solute concentration that the cell will not gain water. Because that's the problem for a bacterial cell, it cannot control the tonicity due to solute concentrations in the surrounding water. Water will flow in or out depending on solute concentrations and the only thing a bacterial cell can do to keep from collapsing due to water loss or rupturing due to too much water coming in is to have a strong cell wall that will hold - answerFalse Since the bacterial cell is at the mercy of the environment, it requires a rigid structure to maintain its shape when osmotic pressure would cause a cell to shrink or expand. The cell wall The cell wall peptidoglycan layer is flexible but still rigid enough to maintain its shape; the cytoplasmic membrane is attached to the cell wall through the use of proteins and lipids A cell wall is a requirement for all living bacteria - answerFalse With the description of the different cell walls, membranes, and associated proteins set in the students' minds, you now need to