Microbiology - Functional Anatomy of Prokaryotic and Eukaryotic Cells

Flashcards covering the functional anatomy of prokaryotic and eukaryotic cells, including cell structures, walls, membranes, and organelles.

Prokaryote

Comes from the Greek words for prenucleus.

Eukaryote

Comes from the Greek words for true nucleus.

Prokaryotic Cell

Usually has one circular chromosome, not in a membrane, no histones, and no phospholipid-membrane-enclosed organelles. Bacteria have peptidoglycan cell walls, Archaea have pseudomurein cell walls and divides by binary fission.

Eukaryotic Cell

Contains paired chromosomes in a nuclear membrane, histones, organelles, polysaccharide cell walls (when present) and divides by mitosis.

Monomorphic Bacteria

Bacteria that maintain a single shape.

Pleomorphic Bacteria

Bacteria that can have many shapes.

Bacillus

Rod-shaped bacteria.

Coccus

Spherical-shaped bacteria.

Spiral Bacteria

Includes Vibrio, Spirillum, and Spirochete shapes.

Diplococci

Pairs of cocci.

Diplobacilli

Pairs of bacilli.

Staphylococci

Clusters of cocci.

Streptococci

Chains of cocci.

Streptobacilli

Chains of bacilli.

Tetrads

Groups of four bacteria.

Sarcinae

Cubelike groups of eight bacteria.

Glycocalyx

External to the cell wall, viscous and gelatinous, made of polysaccharide and/or polypeptide. Can be a capsule (neatly organized) or a slime layer (unorganized and loose).

Capsule

A type of glycocalyx that is neatly organized and firmly attached, contributing to virulence by preventing phagocytosis.

Slime Layer

A type of glycocalyx that is unorganized and loose.

Flagella

Filamentous appendages on the cell surface used to propel bacteria, made of protein flagellin.

Axial Filaments

Also called endoflagella, found in spirochetes, anchored at one end of a cell, rotation causes cell to move like a corkscrew.

Fimbriae

Hairlike appendages that allow for attachment and are involved in the formation of biofilms.

Pili

Involved in motility (gliding and twitching motility) and conjugation.

Cell Wall

Prevents osmotic lysis and protects the cell membrane; made of peptidoglycan in bacteria; contributes to ability to cause disease.

Peptidoglycan

Polymer of repeating disaccharides (NAG and NAM) linked by polypeptides, forming a lattice structure that surrounds and protects the cell.

Gram-Positive Cell Walls

Thick peptidoglycan layer containing teichoic acids, which regulate movement of cations and provide antigenic specificity.

Gram-Negative Cell Walls

Thin peptidoglycan layer with a periplasmic space and an outer membrane made of lipopolysaccharide (LPS), lipoproteins, and phospholipids.

Teichoic Acids

Found in gram-positive cell walls, linking cell wall to plasma membrane and peptidoglycan, carrying a negative charge, and regulating cation movement.

Lipopolysaccharide (LPS)

Found in the outer membrane of gram-negative cell walls; contains O polysaccharide (antigen) and Lipid A (endotoxin).

Acid-fast Cell Walls

Similar to gram-positive cell walls but contain a waxy lipid (mycolic acid) bound to peptidoglycan.

Mycolic Acid

Waxy lipid found in acid-fast cell walls.

Mycoplasmas

Bacteria that lack cell walls; contain sterols in plasma membrane for protection from lysis.

Lysozyme

Hydrolyzes bonds in the glycan portion of peptidoglycan, weakening the cell wall.

Plasma Membrane

Phospholipid bilayer enclosing the cytoplasm, containing peripheral, integral, and transmembrane proteins; selectively permeable.

Simple Diffusion

Movement of a solute from an area of high concentration to an area of low concentration.

Facilitated Diffusion

Movement of ions or larger molecules across the membrane with the concentration gradient, enabled by integral membrane proteins.

Osmosis

Net movement of water across a selectively permeable membrane from an area of higher water concentration to lower water concentration.

Isotonic Solution

Solute concentrations are equal inside and outside the cell; no net movement of water.

Hypotonic Solution

Solute concentration is lower outside than inside the cell; water moves into the cell.

Hypertonic Solution

Solute concentration is higher outside the cell than inside; water moves out of the cell.

Active Transport

Requires a transporter protein and ATP; substance moves against the concentration gradient.

Group Translocation

Requires a transporter protein and phosphoenolpyruvic acid (PEP); substance is altered as it crosses the membrane.

Nucleoid

Region in prokaryotic cells containing the bacterial chromosome, a circular thread of double-stranded DNA.

Plasmids

Small extrachromosomal circles of DNA in bacteria that carry noncrucial genes.

Ribosomes

Sites of protein synthesis; 70S in prokaryotes.

Inclusions

Reserve deposits of certain nutrients within the cytoplasm of prokaryotic cells, such as metachromatic granules, polysaccharide granules, and lipid inclusions.

Endospores

Resting cells produced by certain bacteria when nutrients are depleted; resistant to desiccation, heat, chemicals, and radiation.

Sporulation

The process of endospore formation.

Germination

The process by which an endospore returns to its vegetative state.

Flagella (Eukaryotic)

Long projections used for locomotion or moving substances along the cell surface; consist of microtubules made of tubulin in a 9 + 2 array.

Cilia

Short projections used for locomotion or moving substances along the cell surface; consist of microtubules made of tubulin in a 9 + 2 array.

Cell Wall (Eukaryotic)

Found in plants, algae, and fungi; made of carbohydrates (cellulose, chitin, glucan, and mannan).

Glycocalyx (Eukaryotic)

Carbohydrates bonded to proteins and lipids in the plasma membrane of animal cells; strengthens cell surface and helps with cell attachment and recognition.

Endocytosis

Process by which eukaryotic cells take in substances from their surroundings (phagocytosis, pinocytosis, receptor-mediated endocytosis).

Cytoskeleton

Made of microfilaments, intermediate filaments, and microtubules; gives shape and support to the cell and facilitates cytoplasmic streaming.

Ribosomes (Eukaryotic)

Sites of protein synthesis; 80S in the cytoplasm and ER, 70S in chloroplasts and mitochondria.

Nucleus

Double membrane structure (nuclear envelope) that encloses the cell’s DNA; contains chromatin and chromosomes.

Endoplasmic Reticulum (ER)

Folded transport network; rough ER (with ribosomes) is the site of protein synthesis, and smooth ER (no ribosomes) synthesizes cell membranes, fats, and hormones.

Golgi Complex

Modifies proteins from the ER and transports them via secretory vesicles to the plasma membrane.

Lysosomes

Vesicles formed in the Golgi complex that contain digestive enzymes.

Vacuoles

Cavities in the cell formed from the Golgi complex or by endocytosis; bring food into cells and provide shape and storage.

Mitochondria

Double membrane organelle involved in cellular respiration (ATP production); contains 70S ribosomes and circular DNA.

Chloroplasts

Organelle responsible for photosynthesis; contains thylakoids, chlorophyll, 70S ribosomes, and circular DNA.

Peroxisomes

Oxidize fatty acids.

Centrosomes

Organizing center for the mitotic spindle; plays a critical role in cell division.

Endosymbiotic Theory

Explains the origins of eukaryotes through the engulfment of smaller bacterial cells by larger ones.