Biology: Cell Structure and Function

A complete set of vocabulary flashcards covering cell structure and function, prokaryotes, eukaryotes, organelles, and the cytoskeleton.

Cytology

The study of cells.

Cell Theory

A unifying biological concept originating from work in 1838 to 1839, stating that all organisms are composed of cells, cells come only from preexisting cells, and cells are the basic units of structure and function in organisms.

Matthias Schleiden

A German botanist ($1804\text{ to }1881$) who contributed to the cell theory by identifying that plants are composed of cells.

Theodor Schwann

A German zoologist ($1810\text{ to }1882$) who contributed to the cell theory by identifying that animals are composed of cells.

Rudolph Virchow

A German physician ($1821\text{ to }1902$) who established that cells come only from preexisting cells.

Surface-Area-to-Volume Ratio

A physical relationship requiring cells to remain small (ranging from $1\,mm$ down to $1\,\mu m$ in diameter) because smaller cells have a higher ratio, allowing efficient exchange of materials across the plasma membrane.

Bacteria

A taxonomic domain of prokaryotic organisms that cause diseases, function environmentally as decomposers, and are used to manufacture products and drugs.

Archaea

A taxonomic domain of prokaryotic organisms that live in extreme habitats and are biochemically distinct from bacteria.

Coccus

A spherical-shaped prokaryotic cell.

Bacillus

A rod-shaped prokaryotic cell.

Spirillum

A rigid, spiral-shaped prokaryotic cell.

Spirochete

A flexible, spiral-shaped prokaryotic cell.

Mesosomes

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

Peptidoglycan

A complex molecule that strengthens the cell wall in prokaryotic cells to maintain cell shape.

Glycocalyx

A layer of polysaccharides on the outside of the prokaryotic cell wall, called a capsule when it is well organized and resistant to removal.

Nucleoid

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

Plasmids

Small accessory extrachromosomal rings of DNA found in prokaryotic cytoplasm.

Fimbriae

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

Conjugation Pili

Rigid tubular structures in prokaryotic cells used to pass DNA from cell to cell.

Endomembrane System

A series of intracellular membranes—including the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and vesicles—that compartmentalize the cell and restrict enzymatic reactions.

Cellulose

A structural polysaccharide found inside the cell walls of plant cells.

Nucleolus

A dark area inside the nucleus composed of rRNA that produces ribosomal subunits.

Chromatin

A network of nucleic acids and proteins in the nucleoplasm that condenses to form chromosomes during cell division.

Polyribosomes

Groups of ribosomes located freely within the cytoplasm.

Central Dogma of Molecular Biology

The fundamental sequence of genetic information flow defined as DNA to mRNA to protein.

Signal Recognition Particle (SRP)

A molecular complex that binds to a signal peptide during protein synthesis, temporarily halting synthesis until it binds to an ER receptor.

Rough Endoplasmic Reticulum

Endoplasmic reticulum studded with ribosomes on its cytoplasmic side, responsible for synthesizing, modifying, and processing proteins.

Smooth Endoplasmic Reticulum

Endoplasmic reticulum lacking ribosomes that synthesizes lipids and carbohydrates, detoxifies drugs in the liver, and produces testosterone in the testes.

Golgi Apparatus

An organelle consisting of flattened, curved saccules that receives vesicles on its cis face, modifies and sorts products, and packages them into vesicles at its trans face.

Lysosomes

Highly acidic, membrane-bound vesicles produced by the Golgi apparatus that contain powerful digestive enzymes to digest macromolecules and recycle cellular resources.

Tay-Sachs Disease

A lysosomal storage disease caused by a defect in a specific lysosomal enzyme.

Central Vacuole

A large membranous sac in plant cells that can occupy up to $90\%$ of cell volume, functioning in turgor pressure maintenance and storage of water, nutrients, pigments, and wastes.

Chloroplasts

Double-membrane bounded organelles containing chlorophyll, thylakoids stacked as grana, and stroma, which serve as the sites of photosynthesis in plant cells.

Thylakoids

Disc-like membrane structures within chloroplasts that contain chlorophyll in their membranes and are stacked into grana.

Stroma

The semi-fluid substance suspended within the inner membrane of a chloroplast.

Mitochondria

Double-membrane bounded organelles that carry out cellular respiration, break down carbohydrates, and produce the majority of ATP utilized by eukaryotic cells.

Cristae

The convoluted inner membrane folds of a mitochondrion surrounding the matrix.

Matrix

The inner semifluid substance of a mitochondrion that contains respiratory enzymes to break down carbohydrates.

Actin Filaments

Extremely thin cytoskeletal fibers organized like a twisted pearl necklace that support microvilli, direct cytoplasmic streaming, and interact with myosin in muscle contraction.

Intermediate Filaments

Rope-like cytoskeletal assemblies of fibrous polypeptides that support the nuclear envelope, strengthen cell-cell junctions, and contain keratin in skin cells.

Microtubules

Cytoskeletal fibers that interact with motor molecules kinesin and dynein to transport organelles and form the mitotic spindle during cell division.

Centrioles

Short, hollow cylinders composed of $27$ microtubules arranged in $9$ overlapping triplets, located in pairs within the centrosome of animal cells.

Cilia

Short eukaryotic cell projections that move in coordinated waves like oars to transport material across surfaces.