Microbiology Chapter 5 Quiz

A small, circular, double-stranded DNA molecule found in bacteria. It exists independently of the main chromosome and can replicate itself. Plasmids carry genes that are not essential for basic bacterial survival but provide additional traits like antibiotic resistance, toxin production, and metal tolerance.

The process by which bacteria move towards or away from chemical stimuli. It involves specialized sensory proteins that detect changes in the environment and trigger flagellar movement.

A dormant, highly resistant form of a bacterium that can survive harsh environmental conditions. It contains a core of genetic material surrounded by a thick, protective coat.

The cell wall of bacteria can be categorized into two main types: Gram-positive and Gram-negative. The difference lies in the structure and composition of the cell wall.

The nucleus is a membrane-bound organelle found in eukaryotic cells. It contains the cell's genetic material, DNA, in the form of chromosomes. The nucleus is responsible for controlling and regulating cellular activities.

A chemical solution used in Gram staining that acts as a mordant, stabilizing the crystal violet dye within the peptidoglycan layer of bacterial cell walls. This results in larger dye complexes being trapped more effectively in thicker Gram-positive walls compared to thinner Gram-negative walls.

A decolorizing agent used in Gram staining that dissolves lipids in the outer membrane of Gram-negative bacteria. This weakens the cell wall, allowing the dye complexes to escape, leaving the cells colorless.

A counterstain used in Gram staining to colorize Gram-negative bacteria that have lost their dye during the decolorizing step. This helps to distinguish the Gram-negative cells from the Gram-positive ones.

A staining technique that differentiates bacteria into two main groups based on differences in their cell wall composition. Gram-positive bacteria retain the initial crystal violet dye, appearing purple. Gram-negative bacteria lose the dye after decolorization and are stained red by the counterstain safranin.

A layer of complex carbohydrates found in bacterial cell walls that plays a crucial role in determining the Gram staining result. It's thicker in Gram-positive bacteria, explaining their ability to retain the dye.

A loosely organized, attached layer of glycocalyx that surrounds some bacteria, aiding in attachment to surfaces, protecting against immune cells, and acting as a receptor for certain molecules.

A tough, dormant structure formed by certain bacteria to survive harsh conditions. They are highly resistant to heat, drying, freezing, radiation, and chemicals.

The process by which a vegetative bacterial cell transforms into an endospore. It involves a series of complex steps and allows the bacterium to preserve its genetic material.

The process by which an endospore returns to its vegetative state, allowing it to resume normal growth and division. This occurs when favorable conditions return.

A form of fungi that consists of intertwining filaments called hyphae. These hyphae collectively form a network called mycelium.

Unicellular fungi that propagate through budding or fission. They may form chains called pseudohyphae.

Organisms that obtain nutrients from dead, decomposing organic matter. They play a crucial role in breaking down complex materials.

The nuclear envelope is a double membrane that encloses the nucleus, regulating the movement of molecules in and out. It is studded with nuclear pores, which act as channels for the transport of substances between the nucleus and the cytoplasm.

Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, which stains purple in Gram staining. This thick layer provides structural support and protection.

Gram-negative bacteria have a thin layer of peptidoglycan and an outer membrane containing lipopolysaccharide (LPS). This outer membrane is responsible for their pink staining in Gram staining.

Mycoplasmas are unique bacteria that lack a cell wall, making them more susceptible to osmotic stress and requiring different survival strategies.

Acid-fast bacteria have a high mycolic acid content in their cell walls. Mycolic acid provides resistance to desiccation (drying out) and helps these bacteria survive in harsh environments.

Lipopolysaccharide (LPS) is a complex molecule found in the outer membrane of Gram-negative bacteria. Its lipid A component can trigger immune responses in the host, potentially leading to inflammation, fever, and even shock.

Teichoic acids and lipoteichoic acids are unique molecules present in the cell walls of Gram-positive bacteria. They play a role in cell wall structure, adhesion, and immune recognition.

The periplasmic space is a region between the inner and outer membranes of Gram-negative bacteria. It contains various enzymes and transport proteins involved in nutrient uptake and detoxification.

Variation in the size and shape of bacteria within a single species, often caused by factors like nutrition and genetics.

Bacterial arrangements describe how individual cells group together.

Cocci are spherical bacteria that can arrange in single cells, pairs (diplococci), groups of four (tetrads), irregular clusters (staphylococci or micrococci), or chains (streptococci).

Bacilli are rod-shaped bacteria that can arrange as single cells, pairs with ends attached (diplobacilli), chains (streptobacilli), or palisades, where chains remain linked at the ends like a fence.

Flagella are whip-like structures used for bacterial movement. They can be arranged differently, affecting movement speed and direction. Monotrichous: one flagellum, lophotrichous: a bunch of flagella, amphitrichous: flagella at both ends, peritrichous: flagella all over.

Fimbrae are fine, hair-like structures found on bacterial surfaces that help with attachment to other cells and surfaces, particularly in the formation of biofilms.

A bacterial capsule is a highly organized, tightly attached protective layer external to the cell wall, made of sugars and proteins. It aids in resisting host immune systems and forming biofilms.

A bacterial slime layer is a loosely attached, unorganized layer external to the cell wall, composed of sugars and proteins. It provides some protection and aids in attachment.