Biology I ASB0204: Topic 3 Cell Structure & Function

Vocabulary practice flashcards covering cell theory, prokaryotic and eukaryotic structures, organelle functions, and the cytoskeleton as outlined in the ASB0204 Biology lecture.

Cell Theory

The theory that cells are the basic units of structure/organization and function in organisms, and that all cells come from pre-existing/other cells because they are self-reproducing.

Matthias Schleiden & Theodor Schwann

A German botanist and a German zoologist (1838-1839) who reasoned that all plants and animals consist of cells.

Rudolf Virchow

Scientist who stated in 1855 that new cells form through the division of existing cells.

August Weisman

Scientist who noted in 1880 that the ancestry of all cells of today can be traced based on basic structural and functional similarities.

Prokaryotic cells

Cells that lack a membrane-bound nucleus and are placed into two taxonomic domains: Archaea and Bacteria.

Archaea

Unicellular prokaryotes whose cell walls lack peptidoglycan and which often live in extreme, harsh conditions.

Bacteria

The most diverse and widespread group of unicellular prokaryotes; they possess cell walls containing peptidoglycan.

Coccus

A spherical-shaped prokaryotic cell (plural: cocci).

Bacillus

A rod-shaped prokaryotic cell.

Spirillum

A rigid, spiral-shaped prokaryotic cell.

Sprochete

A flexible, spiral-shaped prokaryotic cell.

Mesosomes

Internal pouches formed by the plasma membrane in prokaryotes that increase surface area.

Cell wall (Prokaryote)

A structure that maintains cell shape and is strengthened by peptidoglycan.

Glycocalyx

A layer of polysaccharides associated with the prokaryotic cell envelope.

Nucleoid

The region in a prokaryotic cell that contains the single, circular DNA molecule.

Plasmids

Small accessory (extrachromosomal) rings of DNA found in prokaryotes.

Ribosomes

Tiny structures in the cytoplasm that serve as the site of protein synthesis; they are composed of rRNA and consist of a large and small subunit.

Flagella

External structures providing motility; in humans/animals, they move the whole cell with a whip-like motion.

Fimbriae

Small, bristle-like fibers that sprout from the prokaryotic cell surface.

Conjugation pili

Rigid tubular structures used to pass DNA from cell to cell (singular: pilus).

Eukaryotic cells

Cells with a membrane-bound nucleus housing DNA and specialized, compartmentalized organelles.

Plasma membrane

A phospholipid bilayer with embedded proteins that separates cell contents from the environment and regulates the passage of materials.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts originated from smaller prokaryotic cells engulfed by a larger eukaryotic ancestor, forming a symbiotic relationship.

Nuclear envelope

A double membrane that separates the nuclear contents from the cytoplasm; it contains nuclear pores.

Chromatin

DNA associated with RNA and certain proteins located in the semifluid nucleoplasm.

Nucleolus

A region within the nucleus that synthesizes rRNA and produces the subunits of ribosomes.

Polyribosomes

A string of ribosomes simultaneously synthesizing the same protein.

Endomembrane system

A network of organelles including the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and vesicles that exchange materials.

Rough ER

Endoplasmic reticulum studded with ribosomes on the cytoplasmic side; it synthesizes proteins and adds sugar to form glycoproteins.

Smooth ER

Endoplasmic reticulum lacking ribosomes; it synthesizes lipids (phospholipids and cholesterol) and breaks down toxins.

Golgi apparatus

Consists of stacks of flattened membranous sacs called cisternae; it processes, sorts, modifies, and packages proteins and lipids.

Lysosomes

Membrane-bound vesicles (rare in plant cells) containing powerful digestive enzymes and a highly acidic environment to digest macromolecules.

Central vacuole

A large, fluid-filled sac in plant cells that stores metabolites, stores water/nutrients, and helps maintain turgor pressure.

Peroxisomes

Microbodies containing specialized enzymes to transfer hydrogen to oxygen, break down fatty acids, and detoxify toxic compounds.

Mitochondria

Energy-converting organelles that carry out cellular respiration to produce ATP; they feature a double membrane and inner folds called cristae.

Chloroplasts

Green organelles found in plants that carry out photosynthesis to produce sugars; they contain disc-like thylakoids stacked into grana.

Cytoskeleton

A dynamic network of protein fibers inside the cytoplasm that maintains cell shape, aids in intracellular transport, cell movement, and cell division.

Microfilaments (Actin filaments)

The thinnest cytoskeleton fibers; they play a role in cell movement, muscle contraction, cell division, and shape.

Intermediate filaments

Cytoskeleton fibers of medium thickness that provide mechanical strength, maintain cell shape, and anchor organelles.

Microtubules

The thickest cytoskeleton fibers; they move chromosomes during cell division and form structures like cilia and flagella.

Centrosome

The microtubule organizing center; in animal cells, it contains a pair of centrioles.

Centrioles

Short cylinders of microtubules that act as the starting point for cilia and flagella; they are not found in plant cells.

Cilia

Short, hair-like extensions from the cell surface that move fluid with a wave-like motion; they occur in large numbers.