Cell Structure and Function Flashcards

Comprehensive vocabulary flashcards generated from lecture notes on cell structure, prokaryotic vs eukaryotic organelles, membrane structure, and passive vs active transport.

Cell Theory

The foundational biological concept stating that all living things are made of cells, cells come from pre-existing cells, and cells are the basic unit of structure and organization of life.

Prokaryotic Cell

A cell type lacking a nucleus and membrane-bound organelles, where DNA is free-floating in the cytoplasm; typical of Domain Bacteria and Domain Archaea.

Eukaryotic Cell

A cell type containing a membrane-bound nucleus housing linear DNA chromosomes and membranous organelles; found in Domain Eukarya (plants, animals, fungi, and protists).

Plasma Membrane

A fluid phospholipid bilayer embedded with proteins, starches, and cholesterol that surrounds the cell, separates internal contents from the outside environment, and regulates passage into and out of the cell.

Cytoplasm

The jelly-like inner filling of a cell consisting of fluid (cytosol) and functional components in which organelles are suspended.

Cytosol

The fluid portion of the cytoplasm composed mostly of water with dissolved sugars and proteins.

Ribosomes

Non-membranous cellular machinery made of rRNA and protein that build proteins; found in all cells, either free-floating in cytoplasm or attached to the endoplasmic reticulum in eukaryotes.

Peptidoglycan

A combination of starch and protein that makes up the prokaryotic cell wall surrounding the plasma membrane in bacteria.

Pili

Cytoplasmic extensions on bacteria used to exchange DNA with other individuals.

Cytoskeleton

A network of protein filaments and fibers that gives structure and support to the cell, transports substances internally, and forms cilia and flagella for cell movement.

Endomembrane System

A group of organelles built from folded membranes—including the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and plasma membrane—that coordinate to produce, modify, package, and transport proteins and lipids.

Nucleus

A eukaryotic membrane-bound organelle surrounded by a double-layer nuclear envelope that houses DNA as chromatin, directs cellular functions, and produces ribosomes in the nucleolus.

Chromatin

A combination of DNA and protein inside the nucleus that condenses into linear chromosomes during eukaryotic organization.

Rough Endoplasmic Reticulum

A network of folded membranes studded with ribosomes that produces and folds proteins, primarily those intended for secretion from the cell.

Smooth Endoplasmic Reticulum

A network of folded membranes lacking ribosomes that synthesizes fats, steroids, carbohydrates, and phospholipids, detoxifies medications and poisons, and stores calcium.

Golgi Apparatus

An organelle composed of folded membranes that sorts, ships, and makes final modifications to products produced by the endoplasmic reticulum.

Lysosomes

Specialized transport vesicles containing an acidic environment and digestive enzymes to break down cellular waste, damaged machinery, and ingested substances.

Peroxisomes

Organelles that break down fatty acids, amino acids, and toxic substances, producing hydrogen peroxide as a by-product while detoxifying harmful compounds like alcohol.

Endosymbiosis

The evolutionary process ("inside together life") by which ancestral eukaryotic cells engulfed free-living bacteria that evolved into specialized energy-converting organelles (chloroplasts and mitochondria).

Chloroplasts

Double-membrane organelles containing chlorophyll pigment found in plant and algae autotrophs that convert solar energy into sugars via photosynthesis.

Mitochondria

Double-membrane organelles present in all eukaryotic cells that convert chemical energy (sugars) into usable cellular energy in the form of ATP.

Cell Wall (Plant)

A rigid outer structure composed of cellulose that surrounds the plasma membrane of plant cells to provide structural support and shape.

Large Central Vacuole

A prominent plant organelle that stores water and other substances while providing turgidity by exerting outward pressure against the cell wall.

Fluid Mosaic Model

The structural representation of the cell membrane as a fluid phospholipid bilayer embedded with proteins, cholesterol, and carbohydrates.

Passive Transport

The movement of substances across a cell membrane down a concentration gradient (from high to low concentration) without expending cellular energy (ATP).

Diffusion

The natural process of molecules spreading out to maximize distance between one another, moving from an area of higher concentration to lower concentration.

Aquaporins

Specialized membrane transport proteins that facilitate the movement of water across the plasma membrane.

Osmosis

The diffusion of water across a membrane toward an area of higher solute concentration.

Tonicity

The measure of the relative solute concentration of one solution compared to another.

Hypertonic Solution

A solution that has a higher solute concentration compared to another solution, causing water to flow out of a cell placed in it.

Hypotonic Solution

A solution that has a lower solute concentration compared to another solution, causing water to flow into a cell placed in it.

Isotonic Solution

A solution that has an equal solute concentration compared to another solution, resulting in equal net movement of water.

Active Transport

The movement of substances across a membrane against a concentration or electrochemical gradient (from low to high concentration), requiring the cell to expend ATP.

Endocytosis

An active transport process in which a cell uses extensions of cytoplasm and membrane vesicles to bring large quantities or particles of material into the cell.

Exocytosis

An active transport process in which a cell uses vesicles to expel or secrete large amounts of material or waste out of the cell.