Microbiology exam part 2

Study Notes

Prokaryotic cells, derived from Greek "prenucleus," differ from eukaryotic cells, which mean "true nucleus."
Prokaryotes contain one circular chromosome that is not membrane-bound, while eukaryotes have paired chromosomes enclosed in a nuclear membrane.
Eukaryotic cells have histones, organelles, and cell walls composed of polysaccharides, unlike prokaryotes.
Prokaryotes reproduce through binary fission, whereas eukaryotes undergo mitosis and possess a mitotic spindle.

Smaller cells have a higher surface-to-volume (S/V) ratio, promoting better nutrient and waste exchange.
They tend to grow more rapidly than larger cells and accumulate mutations faster, leading to quicker evolutionary changes. Eukaryotic cells adapt more slowly.

Prokaryotic cells are characterized by a lack of internal membrane systems and are classified into two domains: Bacteria and Archaea.
Bacteria can be further categorized based on their Gram stain reaction into Gram-positive and Gram-negative.

Cells can divide along one plane to form pairs (diplococci) or chains (streptococci).
Division along two or three planes results in cubical packets (Sarcina) or clusters (Staphylococcus).

Glycocalyx refers to a network of polysaccharides on the cell surface, including capsules and slime layers.
Capsules are well-organized, composed of polysaccharides, and not easily removed; slime layers are less organized and easily detachable.
S-layers are complex layers of glycoprotein found in some bacteria and Archaea.

Provides protection against host defenses and harsh environmental conditions.
Facilitates attachment to surfaces, forming biofilms and interacting with host receptors.
Shields against viral infections, predation, and environmental chemicals.

Dense masses formed by microbes adhering to solid surfaces, such as rocks, pipes, and medical implants.

Flagella are responsible for locomotion; fimbriae facilitate attachment and movement.
Pili come in different types, such as sex pili for genetic exchange, attachment, and secretion.

Fimbriae are short, thin, hair-like structures with up to 1,000 per cell, crucial for surface attachment.
Pili are tubular structures with fewer than 10 per cell, serving roles in attachment and gene transfer.

Flagella consist of chains of the protein flagellin and are anchored to the cell wall and membrane by a basal body.
Motility is achieved through rotation, allowing movement toward or away from stimuli (taxis). Flagella proteins act as H antigens.