Cell Biology: Organelles and Cell Structures

Comprehensive vocabulary flashcards covering eukaryotic and prokaryotic cell structures, organelle functions, and comparisons between animal and plant cells.

Cytosol

The soluble portion left in the cytoplasm without the organelles, consisting of water and dissolved substances.

Cytoplasm

The jelly-like material within the cell containing the organelles.

Nucleus

The control center and largest organelle of the cell, which contains the chromosomal DNA.

Nucleolus

A sub-nuclear structure responsible for making ribosomes.

Nuclear Pores

Circular openings on the surface of the nuclear membrane where ribosomes are found and through which materials move into and out of the cell.

Centrosome

The microtubule organizing center present only in animal cells where microtubules are made; it divides and moves to opposite sides of a dividing cell.

Centrioles

A pair of organelles arranged perpendicular to one another, composed of $9$ sets of triplet microtubules, from which spindle microtubules grow during animal cell division.

Microtubules

Hollow, straw-shaped structures that give shape to both the cell and the nucleus.

Mitochondria

Double membrane-enclosed organelles that convert the potential energy of food molecules into ATP.

Cristae

Elaborately folded, shelflike projections of the inner mitochondrial membrane that extend into the matrix.

Mitochondrial Matrix

The fluid-filled internal space enclosed by the inner mitochondrial membrane.

Rough Endoplasmic Reticulum (Rough ER)

Part of the cytoplasmic membrane network studded with ribosomes where most protein synthesis occurs in the cell.

Smooth Endoplasmic Reticulum (Smooth ER)

A network of membranes that synthesizes lipids and aids in the detoxification of harmful substances in the cell.

Golgi Complex

An organelle responsible for sorting and correctly shipping proteins produced in the endoplasmic reticulum.

Ribosomes

Cellular structures made of large and small subunits that carry out protein synthesis, found free in cytoplasm or attached to the endoplasmic reticulum.

Fluid Mosaic Model

A model that describes the plasma membrane as a bilayer of phospholipids with embedded protein molecules.

Vesicles

Small vessels that function as cellular transport vehicles to deliver materials within the cell or export them to the outside.

Lysosomes

Organelles containing hydrolytic enzymes that serve as the cell's recycling compartment.

Steps in Lysosomal Formation

A three-step sequence: (1) The ER and Golgi apparatus produce a lysosome; (2) The lysosome fuses with a digestive vacuole; (3) Activated acid hydrolases digest the vacuole contents.

Cilia

Thread-like projections on certain cells that beat rhythmically to generate currents that move materials along the cell surface.

Flagella

Long appendages that push a cell forward from behind by snakelike wriggling or pull it forward from the front.

Structures Not Found in Plant Cells

Lysosomes, centrioles, and flagella (with flagella only occurring in certain plant sperm).

Chloroplast

A plant-specific organelle containing chlorophyll where photosynthesis occurs, converting sunlight into chemical energy used to synthesize starch and other carbohydrates.

Chlorophylls

Pigments located within chloroplasts that are responsible for absorbing light energy from the sun.

Cell Wall

A rigid plant boundary formed of cellulose fibrils embedded in a matrix of polysaccharides and structural glycoproteins, providing protection, shape, and nutrient permeability.

Plasmodesmata

Channels between plant cell walls allowing membrane contact, direct transport, and communication between adjacent plant cells.

Vacuoles

Large cellular storage compartments that hold water, waste products, food, and other cellular materials, often occupying most of a plant cell's volume.

Tonoplast

The specialized membrane that bounds the central vacuole in plant cells.

Prokaryotic Cell Size

The typical diameter of a prokaryotic cell, measuring between $0.1 - 10\,\mu\text{m}$.

Eukaryotic Cell Size

The typical diameter of a eukaryotic cell, measuring between $10 - 100\,\mu\text{m}$.

70S Ribosomes

The class of ribosomes found characteristically in prokaryotic cells.

Plasmid

A circular DNA molecule distinct from chromosomal DNA found in prokaryotic cells.