Microbiology Exam 1 (set 2)

Eukaryotes are defined by having a true nucleus with organelles, enclosed DNA associated with histone proteins, and the ability to divide by mitosis. This sets them apart from prokaryotes, archaea, and viruses, which lack one or more of these characteristic features.

Monomorphic refers to prokaryotes that have a consistent and singular shape, as opposed to pleomorphic prokaryotes which can have varying shapes.

Streptococcus bacteria are known for their characteristic arrangement in chains, giving them their name (Strep - chains).

Vibrio is a genus of bacteria that are characterized by their short curved shape.

Spirillum bacteria have a helical shape and use flagella to move by rotating and propelling themselves forward in a corkscrew-like motion.

Glycocalyx acts as a sugar coat on the surface of cells, capsules, and slime layers. It primarily functions in attachment and protection.

The filament is not made of DNA, lipid bilayer membrane, or carbohydrates. It is made of protein called flagellin wrapped like a hollow rope.

Pili are hair-like structures on the surface of bacteria that are primarily used for attachment to surfaces and other cells, as well as for invasion of host cells. They are not involved in energy production, genetic storage, or communication.

Frimbriae are small, hair-like appendages found on some bacteria that are used for attachment to host cells. They are typically short and numerous, making them a good indicator of an infectious organism.

Peptidoglycan is a polymer consisting of sugars and amino acids that forms a major component of the cell walls of bacteria. The correct answer describes the structure accurately, with NAG (N-Acetylglucosamine) and NAM (N-Acetylmuramic acid) forming the backbone chain linked by polypeptides.

Gram negative bacteria have a unique cell wall structure with one or few layers of peptidoglycan, which makes the cell wall weaker compared to Gram positive bacteria. In addition to the peptidoglycan layer, Gram negative bacteria have an outer membrane that contains lipopolysaccharides (LPS), which serve as endotoxins.

Acid Fast bacteria have very little peptidoglycan, and their mycolic acids and waxes help them resist drying out in harsh environments. This characteristic makes them difficult to stain and treat with antibiotics, particularly in cases of TB and leprosy.

Integral proteins play a crucial role in facilitating the transport of molecules across the membrane and are also involved in cell signaling processes. They are embedded within the phospholipid bilayer rather than being located on the surface of the membrane. Additionally, integral proteins are present in both prokaryotic and eukaryotic cells, where they serve essential functions.

Tonicity refers to the relationship between the concentration of solutes inside and outside a cell, which determines the direction and extent of osmosis across a cell membrane.

Endocytosis is a cellular process in which the cell membrane invaginates or folds inward to form a vesicle that contains extracellular fluid, macromolecules, or particles. This process allows the cell to take in substances from the outside environment.

Phagocytosis specifically refers to the engulfment of large particles by cells, not the breakdown of glucose for energy, movement of water, or cell division.

Staphylococcus bacteria are known for their large clusters arrangement, which can be observed under a microscope.

Spirochetes are unique bacteria that use a twisting motion to move, rather than relying on flagella or other methods of locomotion.

Flagella are composed of three main parts: the filament, which is the long, whip-like structure that extends outward from the cell, the hook, which connects the filament to the basal body, and the basal body, which anchors the flagellum to the cell membrane and acts as a motor to rotate the filament.

The hook is the part of the flagella that is attached to the filament and basal body, and it is responsible for rotating the flagella. The other options are not correct because they do not accurately describe the function or location of the hook in relation to the flagella.

Taxis in biology refers to the movement of an organism towards or away from a stimulus. It is a behavioral response to an external stimulus.

Axial filaments are unique to spirochetes and are bundles that wrap around the spirochete cells, providing the characteristic corkscrew movement observed in these bacteria.

Sex pili are longer and fewer in number compared to fimbriae, and they play a crucial role in facilitating the transfer of DNA between bacterial cells.

The cell wall is primarily used for protection and maintaining the shape of the cell. Additionally, it serves as a target for antibiotics due to their unique structure, making them effective against bacteria but not animals.

Gram positive bacteria have a thick peptidoglycan layer in their cell wall, which is linked by teichoic acid. This provides structural support and also plays a role in regulating ion movement and providing antigenic specificity.

Peripheral proteins are not embedded within the phospholipid bilayer or located in the cytoplasm of the cell. They play a role in various cellular functions such as signaling, providing support, and acting as enzymes.

A phospholipid bilayer is composed of polar heads and nonpolar tails, with the tails facing inward and heads facing outward to interact with water and other molecules appropriately.