Nester's Microbiology: Chapter 03 - Prokaryotic and Eukaryotic Cells

Vocabulary practice flashcards covering prokaryotic and eukaryotic cell structures, mechanisms of transport, cell wall compositions, and microscopy/staining techniques based on Chapter 03.

Hans Christian Joachim Gram

A Danish physician who developed methods to stain bacteria in 1884, revealing two different kinds of bacteria which became the basis for the modern Gram stain.

Gram stain

A staining method that identifies two major groups of bacteria—Gram-positive and Gram-negative—according to their cell wall structure and chemistry.

Prokaryotic cells

Cells characterized by a lack of a membrane-bound nucleus; this group includes all members of the domains Bacteria and Archaea.

Eukaryotic cells

Complex cells defined by the presence of a nucleus and membrane-bound compartments; includes animals, plants, protozoa, fungi, and algae.

Cytoplasmic membrane

A selectively permeable phospholipid bilayer embedded with proteins that defines the boundary of the cell.

Fluid mosaic model

A model describing the structure of the cytoplasmic membrane where proteins drift about freely within the lipid bilayer.

Aquaporins

Specialized pore-forming proteins that facilitate the passage of water across the cytoplasmic membrane.

Simple diffusion

The movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached.

Osmosis

The diffusion of water across a selectively permeable membrane due to unequal solute concentrations.

Hypotonic

A solution with a lower solute concentration compared to another solution; typically the environment of prokaryotes relative to their cytoplasm.

Hypertonic

A solution with a higher solute concentration compared to another solution.

Proton motive force

The electrochemical gradient created by the Electron Transport Chain (ETC) which is harvested to drive ATP synthesis, transport, and motility.

Efflux pumps

Transporters that move waste products and toxic substances, such as antimicrobial medications, out of the cell.

Facilitated diffusion

A form of passive transport that moves material down a concentration gradient through a transporter without requiring energy.

Active transport

A process that requires energy to move material against a concentration gradient, often driven by ATP or the proton motive force.

Group translocation

A process common in bacteria where a compound is chemically altered (often via phosphorylation) as it passes through the cytoplasmic membrane.

Peptidoglycan

A unique macromolecule found only in bacterial cell walls, consisting of glycan chains made of alternating subunits of $NAM$ and $NAG$.

N-acetylmuramic acid (NAM)

One of the two alternating sugar subunits that form the glycan chains of peptidoglycan.

N-acetylglucosamine (NAG)

One of the two alternating sugar subunits that form the glycan chains of peptidoglycan.

Gram-positive cell wall

A cell wall characterized by a relatively thick layer of peptidoglycan and the presence of teichoic acids.

Gram-negative cell wall

A cell wall characterized by a thin peptidoglycan layer and an outer membrane containing lipopolysaccharide ($LPS$).

Lipopolysaccharide (LPS)

A molecule in the outer membrane of Gram-negative bacteria also known as endotoxin; it consists of Lipid A and O antigen.

Periplasm

The gel-like material located in the periplasmic space between the cytoplasmic membrane and the outer membrane in Gram-negative bacteria.

Porins

Specialized channel-forming proteins in the outer membrane of Gram-negative bacteria that allow the passage of small molecules and ions.

Penicillin

An antibacterial medication that interferes with peptidoglycan synthesis by preventing the cross-linking of adjacent glycan chains.

Lysozyme

An enzyme found in tears and saliva that breaks the bonds linking glycan chains, destroying the structural integrity of peptidoglycan.

Mycoplasma

A genus of bacteria that naturally lack a cell wall and use sterols in their cytoplasmic membrane for strength.

Capsule

A distinct, gelatinous gel-like layer outside the cell wall that protects the cell or allows it to attach to surfaces.

Slime layer

A diffuse and irregular gel-like layer outside the cell wall that allows for attachment to surfaces and biofilm formation.

Flagella

Protein structures involved in motility that spin like propellers to move the cell.

Chemotaxis

The movement of bacteria toward a nutrient or away from a toxin in a series of runs and tumbles.

Pili

Short, thin appendages; common pili (fimbriae) allow for attachment, while sex pili are used for DNA transfer.

Nucleoid

The gel-like region in a prokaryotic cell that contains the single, circular, double-stranded DNA chromosome.

Plasmids

Small, circular DNA molecules that do not encode essential genetic information but may carry genes for antibiotic resistance.

70S Ribosome

The size of ribosomes found in prokaryotes, composed of $30S$ and $50S$ subunits, involved in protein synthesis.

Endospores

Unique, dormant, and highly resistant cells produced by members of Bacillus and Clostridium that can survive extreme conditions for long periods.

Organelles

Membrane-enclosed compartments within eukaryotic cells that perform specific cellular processes.

Endocytosis

The process by which a eukaryotic cell takes up material from the environment by forming invaginations in the cytoplasmic membrane.

Phagocytosis

A type of endocytosis used by protozoa and phagocytes to engulf particulate material, forming a phagosome.

80S Ribosome

The size of ribosomes found in eukaryotic cells, composed of $40S$ and $60S$ subunits.

Mitochondria

Organelles that generate ATP through pathways that utilize energy from electrons; they contain their own DNA and $70S$ ribosomes.

Endosymbiotic Theory

The theory that the ancestors of mitochondria and chloroplasts were bacteria residing within other cells.

Chloroplasts

Organelles found in plants and algae that serve as sites of photosynthesis, harvesting sunlight to generate ATP.

Endoplasmic Reticulum (ER)

A system of flattened sheets and tubes; Rough ER is for protein synthesis (with ribosomes), and Smooth ER is for lipid synthesis and calcium storage.

Golgi Apparatus

A series of membrane-bound flattened compartments where macromolecules synthesized in the ER are modified, sorted, and delivered.

Lysosomes

Organelles containing degradative enzymes that break down material taken up by the cell or old organelles (autophagy).

Resolution

The ability to distinguish two objects that are very close together; the minimum distance between two points at which they can be observed as separate.

Transmission Electron Microscope (TEM)

A microscope that directs a beam of electrons through a specimen to view internal details.

Scanning Electron Microscope (SEM)

A microscope that scans a beam of electrons over the surface of a specimen to observe surface details in 3-D.

Acid-fast stain

A differential stain used to detect organisms like Mycobacterium that have high concentrations of mycolic acids in their cell walls.