The Living Unit: Cell

Vocabulary flashcards covering key cell structures, organelles, membrane components, and cell types from the lecture notes.

Plasma membrane

The transparent barrier enclosing the cell contents; separates intracellular fluid from extracellular fluid; lipid bilayer with proteins; hydrophilic heads and hydrophobic tails; selectively permeable; forms cell junctions; microvilli increase surface area.

Cytoplasm

Cellular material inside the plasma membrane where most cellular activities occur; contains cytosol, organelles, and inclusions.

Cytosol

Viscous, semitransparent fluid largely made of water; contains proteins, salts and other nutrients.

Organelles

Specialized cellular structures within the cell that perform specific functions; many have membranes and constitute the cell’s metabolic machinery.

Nucleus

Control center of the cell; contains genetic material (DNA); has three regions: nuclear envelope, nucleolus, and chromatin.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores; separates nucleoplasm from cytoplasm.

Nucleolus

Dense region where ribosomes are assembled.

Chromatin

Loose network of DNA and proteins; condenses to form chromosomes during cell division.

Chromosomes

Tightly coiled DNA strands that form during cell division.

Rough endoplasmic reticulum

Network of interconnected sacs with ribosomes on its surface; site of protein synthesis and transport of proteins in vesicles to the Golgi.

Smooth endoplasmic reticulum

Endoplasmic reticulum lacking ribosomes; site of lipid and cholesterol synthesis and detoxification of drugs.

Ribosomes

Protein factories of the cell; small particles made of RNA and protein; sites of protein synthesis.

Mitochondria

Powerhouse of the cell; double-membrane organelles with cristae; site of ATP production via cellular respiration.

Golgi apparatus

Packaging center near the nucleus; stacks of flattened sacs that modify, package, and ship proteins in vesicles for secretion or delivery to lysosomes or membrane.

Lysosome

Digestive center containing enzymes for intracellular digestion.

Peroxisome

Detoxification unit containing enzymes that break down harmful substances.

Centrioles

Rod-shaped bodies near the nucleus made of microtubules; form the mitotic spindle during cell division.

Centrosome

Region near the nucleus that includes a pair of centrioles and organizes microtubules.

Cytoskeleton

Elaborate network of protein filaments (microtubules, microfilaments, intermediate filaments) that supports the cell and moves organelles.

Microtubules

Tubular protein filaments that determine cell shape and organize the mitotic spindle.

Microfilaments

Actin filaments involved in cell movement and muscle contraction; part of the cytoskeleton.

Intermediate filaments

Tough cytoskeletal filaments that resist mechanical stress.

Cilia

Short, hair-like projections on the cell surface that move substances across the cell surface; composed of microtubules.

Flagellum

Long, whip-like projection that propels the cell (e.g., sperm tail); anchored by a basal body.

Microvilli

Finger-like extensions of the plasma membrane that increase surface area for absorption.

Glycocalyx

Carbohydrate-rich coating on the cell surface formed by glycolipids and glycoproteins; involved in cell recognition.

Lipid bilayer

Double layer of phospholipids forming the structure of the plasma membrane, with hydrophilic heads outward and hydrophobic tails inward; contains cholesterol and glycolipids.

Phospholipid

Molecule with a polar, hydrophilic head and a nonpolar, hydrophobic tail; primary component of the lipid bilayer.

Cholesterol

Sterol in the plasma membrane that helps regulate fluidity and stability.

Glycoprotein

Protein with carbohydrate chains; part of the glycocalyx; roles in receptors, transport, and enzymes.

Glycolipid

Lipid with carbohydrate chains; part of the glycocalyx; involved in cell recognition.

Integral proteins

Proteins embedded in the membrane that span the lipid bilayer and function as channels, transporters, or receptors.

Peripheral proteins

Proteins attached to the membrane surface; support the cell and participate in signaling and structure.

Nuclear pores

Openings in the nuclear envelope that regulate exchange of material between the nucleus and cytoplasm.

Nucleoplasm

Jelly-like fluid inside the nucleus.

Vesicle

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

Secretory vesicle

Vesicle that carries secretions to be released outside the cell.

Transport vesicle

Vesicle that moves materials between organelles, such as from the ER to the Golgi.

Vacuole

Sac-like structure; in some contexts a sac of undigested nutrients or stores wastes and water (plant cells have large vacuoles).

Erythrocyte

Red blood cell.

Fibroblast

Cell that produces extracellular matrix and collagen in connective tissue.

Epithelial cell

Cells that connect body parts, form linings, or transport gases.

Muscle cell

Cell that moves or contracts to cause movement of body parts or organs.

Fat cell

Cell that stores nutrients as fat (adipocyte).

Macrophage

Cell that fights disease by phagocytosis.

Neutrophil

White blood cell that helps fight infection.

Nerve cell

Cell that gathers information and controls body functions (neuron).

Sperm

Cell of reproduction.