Microbiology Quiz 2 - Chapter 4

Chemotaxis is the process by which cells move in response to a chemical stimulus. This can involve moving towards or away from the source of the chemical. It is a crucial mechanism for various biological processes such as immune response, wound healing, and the movement of sperm cells towards an egg. Therefore, the correct answer is "Move in response to a chemical."

Bacterial appendages serve two main functions: attachment and motility. Attachment refers to the ability of bacteria to adhere to surfaces, which is important for colonization and biofilm formation. Motility, on the other hand, enables bacteria to move and navigate through their environment. These two functions are crucial for bacterial survival and play a significant role in their ability to interact with their surroundings and carry out various biological processes.

Lysozyme is an enzyme that is found in tears and saliva. It is capable of hydrolyzing the bonds in the glycan chains of certain bacterial cell walls. This means that lysozyme can break down the structure of bacterial cell walls, leading to their destruction. Therefore, lysozyme is an important component of the innate immune system, helping to protect the body against bacterial infections.

Mycobacterium is the correct answer because it is a bacterial genus that is known to have waxy mycolic acid in its cell walls. Mycolic acid is a unique component of the cell wall structure of Mycobacterium species, which gives them their characteristic waxy appearance. This waxy layer helps protect the bacteria from environmental stresses and makes them more resistant to antibiotics and disinfectants. Mycobacterium species include important human pathogens such as Mycobacterium tuberculosis, the causative agent of tuberculosis.

Lipopolysaccharide is a major component of the outer membrane of Gram-negative bacteria. It acts as an endotoxin and is responsible for the strong immune response triggered by these bacteria. Gram-positive bacteria do not have an outer membrane and therefore do not contain lipopolysaccharide. Acid-fast bacteria, mycoplasmas, and protoplasts also do not have lipopolysaccharide in their cell walls. Therefore, the correct answer is Gram-negative bacteria.

Amphitrichous refers to the presence of flagella at both poles of a bacterial cell. This means that the flagella are located at both ends of the cell, allowing for movement in multiple directions. The other options, Atrichous, Lophotrichous, Monotrichous, and Peritrichous, all refer to different arrangements of flagella on a bacterial cell, but none of them specifically indicate flagella at both poles. Therefore, the correct answer is Amphitrichous.

During bacterial conjugation, the transfer of genes occurs through sex pili. Sex pili are rigid, tubular appendages that are used by bacteria to establish contact between donor and recipient cells. These pili allow for the transfer of genetic material, such as plasmids, from one bacterium to another. Unlike flagella, cilia, and fimbriae, which serve different functions such as locomotion or attachment, sex pili specifically facilitate the transfer of genetic material during bacterial conjugation.

Inclusions are not directly involved in the ability of pathogenic bacteria to cause disease. Inclusions are storage granules that allow bacteria to store excess nutrients for later use. While they play a role in the metabolism of bacteria, they do not directly contribute to the ability to cause disease. On the other hand, fimbriae, capsule, slime layer, and the outer membrane of gram-negative cell walls are all structures that contribute to the virulence and pathogenicity of bacteria by aiding in adhesion, evasion of the host immune system, and protection against host defenses.

Endotoxins are specific bacterial cell wall lipids that can stimulate fever and cause septic shock in the human body. They are also involved in typhoid fever and some meningitis cases. However, they are not found in acid fast bacterial cell walls.

Lysozyme is an enzyme that targets the peptidoglycan layer in bacterial cell walls. Gram positive organisms have a thick layer of peptidoglycan, making them more susceptible to lysozyme's action. In contrast, Gram negative organisms have an outer membrane that provides additional protection, making them less susceptible to lysozyme. Mycoplasmas, Cyanobacteria, and Archea have different cell wall compositions, making them less affected by lysozyme. Therefore, the most effective target for lysozyme is Gram positive organisms.

The basal body of a flagellum is anchored into the cell membrane because the cell membrane is the outermost layer of the cell and provides structural support. The flagellum is a whip-like appendage that helps in cell movement, and it needs to be firmly anchored into the cell membrane to function properly. The cell membrane also acts as a barrier, regulating the movement of substances in and out of the cell, so anchoring the flagellum into the cell membrane ensures that it remains securely attached while allowing for the movement of the flagellum.

When gram positive bacteria are exposed to lysozyme or penicillin, they lose their cell wall and become fragile. The term used to describe this fragile cell is "protoplast." A protoplast is a bacterial cell that has lost its cell wall but still retains the cell membrane. This term is specifically used for gram positive bacteria because gram negative bacteria have an outer membrane that protects them from becoming protoplasts. Therefore, the correct answer is protoplast.

The cell membrane is responsible for most ATP synthesis in prokaryotic cells. This is because prokaryotes lack mitochondria, which are the main sites of ATP synthesis in eukaryotic cells. The cell membrane of prokaryotes contains enzymes and transport proteins that are involved in the electron transport chain and ATP synthesis. These enzymes generate ATP by utilizing the energy from the electron transport chain. Therefore, the cell membrane is the primary site for ATP synthesis in prokaryotic cells.