Bacterial Structure and Taxonomy

Comprehensive vocabulary flashcards covering bacterial morphology, cellular structure, taxonomy, domains of life, and clinical significance of various bacterial features as presented by Dr. Md Nurul Islam.

Protista

The single-celled eukaryotes within the five-kingdom classification system.

Monera

The kingdom encompassing prokaryotic organisms.

Archaea

A domain of life containing prokaryotic, unicellular organisms that lack nuclei and often live in extreme environments like high salt or temperature.

Bacteria

Prokaryotic, unicellular organisms lacking nuclei that comprise most human pathogens and reproduce by binary fission.

Eukarya

The domain of life encompassing humans, animals, plants, fungi, and single-celled protists, characterized by cells with nuclei.

Viruses

Unique, acellular, metabolically inert organisms that have no cytoplasm and replicate only within living host cells.

Binary fission

The process of reproduction in bacteria where a parent cell divides into two similar cells.

Cocci

Bacteria with a spherical shape.

Bacilli

Bacteria with a rod-like shape.

Spirochaetes

Bacteria with a helical or spiral shape that move using an axial filament.

Pleomorphic

Bacteria with variable shapes that can appear as both coccal and bacillary forms.

Diplococci

Bacteria arranged in pairs.

Streptococci

Bacteria arranged in chains.

Staphylococci

Bacteria arranged in grape-like clusters.

Gram stain

A clinical microbiology stain that divides bacteria into Gram-positive (purple) and Gram-negative (pink/red) based on cell wall characteristics.

Peptidoglycan

A rigid multilayered structure found in the bacterial cell wall; it is much thicker in Gram-positive bacteria than in Gram-negative bacteria.

Lipopolysaccharide (LPS)

An extremely toxic endotoxin found in the outer membrane of Gram-negative bacteria, responsible for disease features such as fever and shock.

Mycolic acids

Lipids found in the cell walls of acid-fast organisms, such as Mycobacterium tuberculosis, which cannot be Gram stained.

Flagella

Whip-like filaments that act as propellers to guide bacteria toward nutritional sources.

Peritrichous

The arrangement of flagella located all over the outer surface of a bacterium.

Pili

Fine, hair-like filaments composed of the protein pilin, found mainly on Gram-negative organisms, which mediate adhesion to human cell surfaces.

Sex pilus

A specialized pilus that forms the attachment between donor and recipient bacteria during conjugation for the transfer of genes.

Glycocalyx

A polysaccharide slime layer coating the outer surface of many bacteria, allowing firm adherence to structures like teeth and heart valves.

Capsule

An amorphous, gelatinous layer surrounding bacteria that hinders phagocytosis and correlates with virulence.

Cytoplasmic membrane

A phospholipid bilayer located inside the peptidoglycan layer that handles active transport, energy generation, and secretion of enzymes.

Mesosome

A convoluted invagination of the cytoplasmic membrane that functions as the origin of the transverse septum during cell division.

Nucleoid

The inner region of the bacterial cytoplasm containing the single, supercoiled, circular chromosome.

Bacterial Ribosomes

Sites of protein synthesis in bacteria, characterized by a size of $70S$.

Bacterial Spores

Dormant, metabolically inert forms of bacteria produced by genera like Bacillus and Clostridium in response to adverse conditions.

Calcium dipicolinate

A substance found in high concentrations within the keratin-like coat of bacterial spores, contributing to their resistance to heat and chemicals.

Taxonomy

The systematic classification and categorization of organisms into ordered groups based on evolutionary relatedness or genetic homogeneity.

Genotypic taxonomy

A method of classification that evaluates the degree of DNA homology, molecular guanine and cytosine ($GC$) content, and ribotyping.

Core microbiome

The total microbial community within a defined habitat, including both culturable and unculturable organisms and biomolecules.

Microbiota

The total collection of resident microbes within the core microbiome.

Binomial nomenclature

The system of naming organisms using two ranks: the generic name (capitalized) followed by the species name (lowercase), typically written in italics.