Cell Theory, Cell Structure, and Organelles - VOCABULARY Flashcards

Vocabulary flashcards covering cell theory, cell structure, organelles, and related concepts from the lecture notes.

Cell theory

A fundamental principle stating that all organisms are composed of one or more cells, cells are the smallest units of life, and new cells arise from pre-existing cells.

Cell

The basic unit of life that carries out the functions of living organisms.

Unicellular organism

An organism made up of a single cell that carries out all life functions.

Prokaryote

A cell lacking internal membranes and organelles, with DNA in a nucleoid, 70S ribosomes, and no nuclear envelope; generally small (<10 μm).

Eukaryote

A cell with internal membranes and organelles, linear chromosomes, 80S ribosomes, and a nuclear envelope; typically larger than 10 μm.

Nucleoid

Region in prokaryotic cells where free DNA is located, not enclosed by a membrane.

Nuclear envelope

A double-membrane boundary that surrounds the nucleus in eukaryotic cells.

Cytoskeleton

A network of structural proteins (microfilaments, intermediate filaments, microtubules) that supports the cell and facilitates movement.

Mitochondrion

Organelle responsible for energy production; contains its own DNA and ribosomes.

Chloroplast

Plastid in plants and algae that conducts photosynthesis; contains chlorophyll and its own DNA.

Endomembrane system

Group of membranes and organelles (including the nuclear envelope, ER, and Golgi) that compartmentalize intracellular processes.

Nucleus

Membrane-bound organelle that houses genetic material (chromatin) and the nucleolus.

Nucleolus

Region within the nucleus where ribosomal RNA synthesis occurs.

Chromatin

DNA-protein complex that condenses to form chromosomes during cell division.

Chromosome

Structure containing DNA that organizes genetic information; linear in eukaryotes.

Ribosome

Small particle composed of rRNA and protein where protein synthesis occurs; 70S in prokaryotes, 80S in eukaryotes.

70S ribosome

Ribosomes typical of prokaryotes and of mitochondria/chloroplasts; smaller subunit size.

80S ribosome

Ribosomes typical of eukaryotic cytoplasm; larger subunit size.

Endoplasmic reticulum

Network of membranes; site of protein and lipid synthesis; continuous with the nuclear envelope.

Rough endoplasmic reticulum

ER with ribosomes on its surface; involved in protein synthesis and transport.

Smooth endoplasmic reticulum

ER without ribosomes; synthesizes lipids and participates in detoxification.

Golgi apparatus

Stacked membrane-bound sacs (cisternae) that modify, package, and transport materials; makes lysosomes in some contexts.

Vesicle

Small membrane-bound sac that transports materials between organelles and to the membrane.

Lysosome

Organelle containing enzymes for digestion and recycling of cellular material.

Plasma membrane

Phospholipid bilayer that encloses the cell, regulating material movement and signaling.

Cell wall

Rigid layer outside the plasma membrane that provides shape and protection (present in plants and many prokaryotes).

Flagellum

Structure used for cell motility in some cells.

Central vacuole

Large vacuole in plant cells that stores water and maintains turgor pressure.

Tonoplast

Membrane surrounding the central vacuole in plant cells.

Centrosome

Microtubule organizing center in many eukaryotic cells.

Centriole

Cylindrical cell structure found in animal cells; involved in organizing spindle fibers during cell division.

Peroxisome

Organelle involved in lipid metabolism and detoxification processes.

Microvilli

Microscopic projections of the plasma membrane that increase surface area for absorption.

Villus (villi)

Folds of mucosa in the intestine that increase surface area for nutrient absorption.

Plasmodesmata

Channels through plant cell walls that connect neighboring plant cells.

Microtubules

Hollow tubes of tubulin molecules that support the cell and form the mitotic spindle.

Microfilaments

Thin protein filaments (actin) involved in cell movement and shape changes.

Intermediate filaments

Cytoskeletal elements providing mechanical support and integrity.

Surface area-to-volume ratio

A measure of how the surface area of a cell compares to its volume; influences the rate of exchange with the environment.

Viruses

Non-cellular infectious agents smaller than cells, up to about 100 nm in size.