BIOL 1000 Lecture 5 - Prokaryotic and Eukaryotic Diversity

50 vocabulary flashcards covering the key terms, cellular structures, genomic components, cell division mechanisms, cell walls, and domain comparisons of Bacteria and Archaea based on BIOL 1000 Lecture 5.

LUCA

The Last Universal Common Ancestor, represented by the node on the tree of life that gives rise to all living organisms alive today.

Domain Bacteria

One of the three domains of life, comprising unicellular prokaryotic organisms with cell walls containing peptidoglycan.

Domain Archaea

One of the three domains of life, consisting of prokaryotic organisms that lack peptidoglycan in their cell walls and often inhabit extreme environments.

Domain Eukarya

One of the three domains of life, comprising organisms composed of cells containing a distinct nucleus enclosed by a nuclear envelope.

Eukaryotic Cell

A cell type featuring a distinct nucleus surrounded by a nuclear envelope and membrane-bound organelles belonging to the endomembrane system.

Prokaryotic Cell

A cell type characterized by the absence of a membrane-enclosed nucleus, storing its genetic material in a nucleoid region.

Nucleoid

The non-membrane-bound region in a prokaryotic cell where the main circular chromosome is localized.

Bacterial Chromosome

The primary genetic material in most bacteria, usually consisting of a single, circular DNA molecule.

Bacterial Plasmid

A small circular DNA molecule in bacteria that replicates independently of the chromosome and carries non-essential genes that offer beneficial functions such as antibiotic resistance or toxin production.

Binary Fission

The bacterial cell division process encompassing DNA replication, chromosome partitioning, and cytokinesis.

ParM Proteins

Bacterial proteins responsible for actively pushing replicated chromosomes apart toward opposite poles during cell division.

FtsZ Protein

A cytoskeletal protein in bacteria that forms a ring at the division site and constricts to direct cell wall and plasma membrane infolding during cytokinesis.

MreB Protein

A bacterial cytoskeletal protein that forms helical filaments inside the cell and plays a major role in determining and maintaining cell shape.

Bacterial Ribosome

A macromolecular complex consisting of RNA and protein in the bacterial cytoplasm that carries out protein synthesis.

Bacterial Organelles

Membrane-enclosed compartments in certain bacteria specialized for storing substances such as calcium, magnetite, or specific enzymes.

Bacterial Plasma Membrane

The selectively permeable boundary of a bacterial cell that functions in transport and cellular metabolic activities such as ATP production.

Photosynthetic Membranes

Internal membrane structures derived from the plasma membrane in photosynthetic bacteria that house photosynthetic machinery.

Cyanobacteria

A group of oxygenic photosynthetic bacteria widespread in lakes, rivers, and oceans that contain chlorophyll.

Gram-Positive Bacteria

Bacteria having a cell wall composed of a single, relatively thick layer of peptidoglycan that retains crystal violet stain and appears purple.

Gram-Negative Bacteria

Bacteria with a cell wall featuring a thin layer of peptidoglycan enclosed by an outer membrane composed of lipopolysaccharides, lipoproteins, and phospholipids, appearing pink after Gram staining.

Peptidoglycan

A complex polymer forming bacterial cell walls, consisting of carbohydrate glycan backbones connected by peptide cross-links.

Gram-Negative Outer Membrane

A lipid bilayer structure outside the thin peptidoglycan layer of Gram-negative bacteria made up of lipopolysaccharides, lipoproteins, and phospholipids.

Lysozyme

An enzyme that breaks down peptidoglycan bonds in bacterial cell walls, causing cell wall weakening, lysis, and cell death.

Glycocalyx

A outer layer of polysaccharides (and sometimes protein) surrounding the bacterial cell wall that provides protection against desiccation, extreme temperatures, antibiotics, viruses, and host antibodies.

Slime Layer

A loosely associated and highly hydrated form of bacterial glycocalyx.

Capsule

A glycocalyx structure that is tightly associated with the cell wall and contains less water than a slime layer.

Flagellum

A long extracellular appendage on prokaryotic cells used specifically for cellular movement and swimming.

Fimbriae

Short, hair-like extracellular appendages on prokaryotic cells used for attachment to surfaces or host cells during infection, but not involved in motility.

Helicobacter pylori

A species of bacteria that utilizes flagella for cellular motility.

Acinetobacter calcoaceticus

A bacterial species whose surrounding capsular material can be visualized using an India ink suspension light microscope preparation.

Mycoplasma mycoides

One of the smallest known bacterial species, measuring far smaller than the typical $1\,\mu\text{m}$ bacterial diameter.

Thiomargarita namibiensis

One of the largest known bacterial species, measuring up to $100\,\mu\text{m}$ in diameter.

Campylobacter jejuni

A bacterial species that exhibits a spiral cell morphology.

Oscillatoria limosa

A filamentous cyanobacterial species that demonstrates gliding motility.

Pseudomonas aeruginosa

A motile bacterial species capable of swimming.

Archaeal Information System

The cellular machinery governing transcription, translation, and ribosome structure in Archaea that shares closer structural similarities to Eukarya than to Bacteria.

Archaeal Cell Wall

An outer cell boundary found in most Archaea that lacks peptidoglycan and is structurally distinct from bacterial cell walls.

Archaeal Membrane Lipids

Unique chemical lipids forming the plasma membrane of Archaea that differ structurally from those in both Bacteria and Eukarya.

Human Microbiome

The aggregate of microorganisms living on and in the human body, which includes commensal Archaea despite there being no identified human archaeal pathogens.

Endomembrane System

A system of internal membrane-bound compartments characteristic of eukaryotic cells that includes organelles derived from or interacting with the nuclear envelope.

Z-ring

A ring assembly composed of FtsZ protein that forms around the middle of a bacterial cell prior to division and constricts during cytokinesis.

Supercoiled Plasmids

The highly compacted, twisted physical state assumed by circular plasmid DNA molecules inside bacterial cells.

Glycan Chains

Parallel chains made of alternating sugar subunits that form the carbohydrate structural backbone of peptidoglycan.

Peptide Cross-links

Short amino acid chains that form cross-bridges between parallel glycan chains in peptidoglycan to form a sturdy cell wall lattice.

Bacterial Cytoskeleton

An internal protein network within bacterial cells, including FtsZ and MreB proteins, that provides structural support, maintains cell shape, and guides cell division.

Antibiotics targeting peptidoglycan synthesis

Antimicrobial agents that interrupt the formation of peptidoglycan, weakening the cell wall and causing cell rupture.

Bacterial Morphological Diversity

The extensive structural variation in bacterial size (ranging from $0.5\,\mu\text{m}$ to $100\,\mu\text{m}$), cell shape (spheres, rods, spirals), and motility mechanisms.

Nostoc sp.

A genus of cyanobacteria whose chlorophyll-containing cells assemble into chain-like filaments commonly found in aquatic environments.

Prokaryote Size relative to Eukaryote

On average, prokaryotic cells are about $10$ times smaller in diameter and about $1000$ times smaller in volume than eukaryotic cells.

Common Ancestor of Archaea and Eukaryotes

The phylogenetic node indicating that Domain Archaea and Domain Eukarya share a more recent common ancestor with each other than either does with Domain Bacteria.