Chapter 3: Cell Structure, Membrane, Transport, and Organelles (Vocabulary)

A comprehensive set of vocabulary flashcards covering cell structure, membrane organization, transport mechanisms, and intracellular organelles based on the lecture notes (Sections 3.1–3.4).

Cell

The basic structural and functional unit of life; all organisms are composed of cells and cell products.

Cell theory

Principle stating that all organisms are composed of cells, cells are the basic unit of life, cellular activity reflects their organelles, and life propagates via cellular activity.

Cytosol

Liquid portion of the cytoplasm where cellular metabolism occurs.

Nucleus

Control center of the cell that contains genetic material and dictates protein synthesis.

Nuclear envelope

Double membrane surrounding the nucleus; outer membrane continuous with rough ER and contains nuclear pores.

Nucleoplasm

Fluid within the nucleus excluding the nucleolus.

Nuclear pores

Channels in the nuclear envelope that regulate transport of large molecules between the nucleus and cytoplasm.

Nucleolus

Dense region within the nucleus where ribosomal RNA (rRNA) synthesis and ribosome assembly occur.

Chromatin

DNA–protein complex inside the nucleus; condenses to form chromosomes during cell division.

Histone

Protein around which DNA winds to form nucleosomes; modulates gene expression.

Nucleosome

Unit of DNA wrapped around a histone core; basic repeating unit of chromatin.

Chromosome

Condensed chromatin that forms during cell division and contains genetic material.

Ribosome

Ribonucleoprotein particles that synthesize proteins; exist free in cytosol or attached to rough ER.

Rough endoplasmic reticulum

ER with attached ribosomes; synthesizes proteins and certain phospholipids.

Smooth endoplasmic reticulum

ER lacking ribosomes; metabolizes lipids, synthesizes cholesterol, detoxifies substances.

Golgi apparatus

Stacked membranes that modify, sort, and package proteins/lipids for secretion or delivery to membranes.

Lysosome

Membranous organelle with digestive enzymes that degrade biomolecules.

Peroxisome

Organelle containing enzymes that break down fatty acids and detoxify harmful substances.

Mitochondrion

Powerhouse of the cell; produces ATP via cellular respiration; contains its own DNA and RNA.

Cristae

Folded inner mitochondrial membrane surfaces that increase mitochondrial surface area for energy production.

Mitochondrial matrix

Fluid inside mitochondrion where the Krebs cycle occurs.

Centrosome

Microtubule organizing center that anchors microtubules and regulates cell division.

Centriole

Paired cylindrical structures within the centrosome that organize spindle formation during cell division.

Cytoskeleton

Network of protein filaments that supports cell structure and enables movement.

Microfilament

Thinnest cytoskeletal element composed of actin; involved in motility and shaping the cell.

Intermediate filament

Cytoskeletal element providing tensile strength and resisting mechanical stress.

Microtubule

Thickest cytoskeletal filament made of tubulin; radiates from the centrosome and moves organelles.

Desmosome

Junction that anchors cells together, providing mechanical stability; linked to intermediate filaments.

Gap junction

Intercellular channel formed by connexons that allows ions and small molecules to pass between cells.

Glycocalyx

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

Glycoprotein

Protein with carbohydrate chains on the cell surface; components of glycocalyx and cell identity markers.

Glycolipid

Lipid with carbohydrate chains that contributes to the glycocalyx and cell recognition.

Cell-identity marker

Glycoprotein on the cell surface that helps distinguish the body's own cells from foreign cells.

Cell-adhesion molecule (CAM)

Glycoprotein that binds one cell to another, facilitating adhesion.

Glycocalyx patterns

Diverse sugar distributions on cell surfaces that aid in cell recognition.

Microvilli

Fingerlike projections that increase surface area for absorption; nonmotile.

Primary cilium

Nonmotile 'antenna' on most cells that senses the environment.

Cilia

Hairlike, usually motile structures that sweep substances across surfaces.

Flagellum

Long, whip-like tail (as in sperm) providing movement.

Osmolarity

A measure of solute concentration; used to compare solutions.

Tonicity

The effect of a solution on cell volume (hypertonic, isotonic, hypotonic).

Isotonic

Solutions with equal solute concentration.

Hypertonic

Solution with higher solute concentration than another solution.

Hypotonic

Solution with lower solute concentration than another solution.

Aquaporin

Water channel protein that facilitates osmosis across the plasma membrane.

Selectively permeable membrane

Membrane that allows some substances to cross more easily than others.

Simple diffusion

Movement of a substance from higher to lower concentration without energy.

Facilitated diffusion

Diffusion through transport proteins or channels; no energy required.

Endocytosis

Vesicular process that brings material into the cell.

Phagocytosis

'Cell eating'—engulfing large particles into a phagosome for digestion.

Pinocytosis

'Cell drinking'—uptake of extracellular fluid and solutes via vesicles.

Receptor-mediated endocytosis

Selective endocytosis where particles bind to receptors and are internalized in clathrin-coated vesicles.

Clathrin-coated vesicle

Vesicle formed during receptor-mediated endocytosis with a clathrin coat.

Exocytosis

Release of materials from the cell via vesicles fusing with the plasma membrane.

SNARE proteins

Proteins that mediate vesicle docking and fusion with the plasma membrane during exocytosis.

Endomembrane system

Interconnected membranes (ER, Golgi, lysosomes, nuclear membrane) involved in production, storage, and transport of biomolecules.

Secondary active transport

Uses ion gradients created by primary active transport to move substances; includes symport and antiport.

Symport

Secondary active transport moving two substances in the same direction.

Antiport

Secondary active transport moving two substances in opposite directions.

Sodium–potassium pump (Na+/K+-ATPase)

Active transporter that moves Na+ out and K+ in, maintaining membrane gradients.

Primary active transport

Energy from ATP hydrolysis drives transport; carrier protein is phosphorylated to change conformation.

Secondary active transport

Relies on ion gradients from primary transport to move substances; includes symport and antiport.

Endosome

Vesicular compartment involved in sorting endocytosed material (not explicitly named in every note, but related to endocytosis).