Cell Structure and Function Flashcards

Comprehensive vocabulary flashcards covering cell structure, organelles, membranes, and cellular junctions from Campbell Biology, Ninth Edition.

Plasma membrane

A selective barrier that divides the cell from its outside environment, controlling what enters and leaves while allowing sufficient passage of oxygen, nutrients, and waste to service the cell volume.

Cytosol

The semifluid, jelly-like substance inside the cell in which subcellular components are suspended, providing a medium to hold organelles and support chemical reactions.

Chromosomes

Structures inside cells that carry genetic information in the form of DNA molecules.

Ribosomes

Cellular complexes composed of ribosomal RNA and protein that carry out protein synthesis in the cytosol or on the outside of the endoplasmic reticulum or nuclear envelope.

Nucleoid

An unbound, non-membrane-enclosed region in a prokaryotic cell where its DNA is concentrated.

Nuclear envelope

A double membrane, each layer consisting of a lipid bilayer, that encloses the cell nucleus to separate its contents from the cytoplasm.

Nuclear lamina

A netlike array of protein filaments that maintains the shape of the nucleus by supporting the nuclear envelope.

Chromatin

The complex of DNA and proteins that forms eukaryotic chromosomes; condenses to form discrete chromosomes as a cell prepares to divide.

Nucleolus

A specialized structure within the nucleus where ribosomal RNA (rRNA) synthesis occurs and ribosomal subunits are assembled.

Endomembrane system

A collection of eukaryotic membranes—including the nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, and plasma membrane—that regulates protein traffic and performs metabolic functions.

Smooth ER

The portion of the endoplasmic reticulum lacking ribosomes; synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, and stores calcium ions.

Rough ER

The portion of the endoplasmic reticulum studded with ribosomes; secretes glycoproteins, distributes transport vesicles, and acts as a membrane factory for the cell.

Glycoproteins

Proteins covalently bonded to carbohydrates, synthesized and secreted by bound ribosomes on the rough ER.

Transport vesicles

Membranous sacs in transit from one part of the cell to another, carrying proteins surrounded by membranes.

Golgi apparatus

An organelle consisting of flattened membranous sacs (cisternae) that modifies ER products, manufactures macromolecules, and sorts and packages materials into transport vesicles.

Cisternae

Flattened membranous sacs that form the structural components of the Golgi apparatus and endoplasmic reticulum.

Lysosome

A membranous sac of hydrolytic enzymes in animal cells that digests macromolecules (proteins, fats, nucleic acids, polysaccharides) in an acidic environment.

Phagocytosis

A cellular process in which a cell engulfs another cell or large particle, forming a food vacuole that fuses with a lysosome for digestion.

Autophagy

A recycling process in which lysosomes use hydrolytic enzymes to break down and recycle the cell's own damaged organelles and macromolecules.

Contractile vacuole

A membranous sac found in many freshwater protists that pumps excess water out of the cell to maintain osmotic balance.

Central vacuole

A large membrane-bounded organelle in mature plant cells that stores water, ions, and organic compounds while facilitating cell growth.

Mitochondrion

A double-membrane organelle found in eukaryotic cells that serves as the site of cellular respiration, generating ATP using oxygen.

Cristae

Infoldings of the inner mitochondrial membrane that provide a large surface area for enzymes involved in ATP synthesis.

Mitochondrial matrix

The internal compartment enclosed by the inner mitochondrial membrane, containing enzymes, mitochondrial DNA, and free ribosomes.

Chloroplast

A photosynthetic organelle found in plants and algae that contains chlorophyll, thylakoids, and stroma to convert light energy into chemical energy.

Thylakoids

Flattened, membranous sacs inside chloroplasts that are stacked into grana and convert light energy into chemical energy during photosynthesis.

Stroma

The fluid portion inside the inner membrane of a chloroplast surrounding the thylakoid membranes, containing chloroplast DNA and ribosomes.

Plastids

A family of closely related plant organelles that includes chloroplasts, chromoplasts, and amyloplasts.

Peroxisome

A specialized metabolic compartment bounded by a single membrane that produces hydrogen peroxide ($H_2O_2$) while breaking down molecules, then converts it into water.

Endosymbiont theory

The evolutionary theory stating that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell, coevolving into a single organism.

Cytoskeleton

A network of fibers (microtubules, microfilaments, intermediate filaments) extending throughout the cytoplasm that maintains cell shape, anchors organelles, and interacts with motor proteins for cell motility.

Plasmodesmata

Open channels perforating plant cell walls that connect the cytoplasm of adjacent cells, allowing water, small solutes, proteins, and RNA to pass.

Tight junctions

Intercellular junctions in animal cells where neighboring cell membranes press tightly together to form a continuous seal that prevents fluid leakage across tissues.

Desmosomes

Anchoring intercellular junctions in animal cells that fasten cells together into strong sheets, anchored by intermediate filaments.

Gap junctions

Communicating intercellular junctions in animal cells that form cytoplasmic channels between adjacent cells, allowing ions, sugars, and small molecules to pass.