JeffState Microbiology Ch #4

What structures do all bacteria possess?

Cytoplasmic membrane, bacterial chromosome/nucleoid, ribosomes, and cytoplasm.

What are four structures that some bacteria possess?

Cell wall, outer membrane, S layer, glycocalyx/capsule.

What are the three major shapes of bacteria?

Coccus (spherical), bacillus (rod-shaped), and curved (vibrio, spirillum, spirochete).

What is pleomorphism in bacteria?

Variations in size and shape among cells of a single species due to nutritional or genetic differences.

What is the function of the bacterial cell wall?

Provides structural support and shape to the bacterium.

What is the role of ribosomes in bacteria?

Sites of protein synthesis.

What is the average size of bacteria?

Approximately 1 µm.

What is the function of fimbriae?

Aid in adhesion to surfaces and cells.

What is a flagellum?

A specialized appendage for motility that pushes the cell forward.

What is the difference between a slime layer and a capsule?

A slime layer is a loose coating, while a capsule is a denser, thicker coating tightly bound to the cell.

What is chemotaxis?

Movement of bacteria in response to chemical signals.

What is positive chemotaxis?

Movement toward a favorable stimulus.

What is negative chemotaxis?

Movement away from a harmful repellent.

What are the three parts of a bacterial flagellum?

Filament, hook, and basal body.

What is the function of the glycocalyx?

Functions in protection, adhesion, and reception.

What is an endospore?

A dormant body formed within a cell allowing survival under adverse conditions.

What is a pilus used for?

To draw another bacterium close for DNA transfer (conjugation).

What are nanowires/nanotubes?

Thin tubular extensions allowing electron or nutrient transmission between cells.

What is the role of the outer membrane in some bacteria?

Controls material flow and contains lipopolysaccharide (LPS), which can cause immune reactions.

What is the function of the actin cytoskeleton in bacteria?

Contributes to cell shape with long protein fibers encircling the cell.

What is the significance of biofilms?

Microbial habitats where bacteria live in cooperative associations.

What is the term for pairs of cocci?

Diplococci.

What are tetrads in bacterial arrangements?

Groups of four cocci.

What are streptococci?

Chains of a few to hundreds of cocci.

What is the term for a chain of rod-shaped bacteria?

Streptobacilli.

What is the role of the S layer?

Provides protection in hostile environments.

What is the difference between a 'run' and a 'tumble' in bacterial movement?

'Run' is a straight movement, while 'tumble' is a random change in direction.

True or False: Bacterial fimbriae are used for conjugation.

False - Pili are used for conjugation.

What are the main structural differences between capsules and biofilms?

Capsules are well-defined structures surrounding the cell, while biofilms are complex communities of bacteria adhering to surfaces.

What are the two main types of bacterial envelope structure?

Gram-positive and Gram-negative.

Why are gram-positive cell walls stronger than gram-negative cell walls?

Gram-positive walls have a thicker peptidoglycan layer.

What substance in the envelope structure of some bacteria can cause severe symptoms in humans?

Lipopolysaccharide (LPS).

What is the structure of peptidoglycan?

Repeating long glycan chains (N-acetylglucosamine and N-acetylmuramic acid) cross-linked by short peptide chains.

What is unique about the cell walls of Mycobacterium and Nocardia?

They contain mycolic acid, contributing to pathogenicity and chemical resistance.

What are endospores?

Dormant bodies produced by some bacteria, capable of withstanding extreme conditions.

What triggers sporulation in bacteria?

Depletion of nutrients, especially carbon or nitrogen.

What is the primary stain used in the Gram stain mechanism?

Crystal violet.

What happens during the decolorization step of the Gram stain?

Alcohol dissolves outer membrane lipids in Gram-negative cells, washing out the dye.

What is the difference between bacterial ribosomes and eukaryotic ribosomes?

Bacterial ribosomes are 70S, while eukaryotic ribosomes are 80S.

What are plasmids?

Nonessential double-stranded circles of DNA that confer adaptive traits.

What type of bacteria is characterized by the presence of teichoic acid?

Gram-positive bacteria.

What are the four divisions of bacteria ending in -cutes?

Gracilicutes, Firmicutes, Tenericutes, Mendosicutes.

What is the definition of a bacterial species?

A collection of bacterial cells sharing an overall pattern of similar traits.

What is the role of porins in the bacterial outer membrane?

They form channels allowing small molecules to pass through.

What are methanogens?

Archaea that convert CO2 and H2 into methane gas in anaerobic environments.

What is the significance of the Gram stain?

It differentiates between gram-positive and gram-negative bacteria based on cell wall structure.

What does the term 'extremophiles' refer to?

Organisms that thrive in extreme environmental conditions.

What is the function of the cytoskeleton in bacteria?

It contributes to cell shape.

Name a disease caused by spore-forming bacteria.

Anthrax (Bacillus anthracis).