Chapter 3 Cellular Form and Function - Vocabulary Flashcards

Vocabulary flashcards covering cellular structure, surface, transport, and interior components from the notes.

Cytology

The science of cells; originated in 1663 when Robert Hooke observed cork cell walls and called them cellulae.

Cell theory

Modern idea that cells arise from other cells; all organisms are cellular or cellular products; cells are the basic unit of life; cellular activity explains structure and function; biochemical unity across species.

Squamous cell

Thin, flat cell shape that may bulge where the nucleus lies.

Cuboidal cell

Cube-like shape; roughly as tall as it is wide.

Columnar cell

Tall, column-like shape; markedly taller than wide.

Polygonal cell

Angular shape with four or more sides.

Stellate cell

Star-shaped cell, such as a nerve cell.

Spheroid

Round to oval cell shape.

Ovoid

Egg-shaped or oval cell shape.

Discoid

Disc-shaped cell, such as red blood cells.

Fusiform

Thick in the middle and tapered at the ends, e.g., smooth muscle cells.

Fibrous cell

Threadlike shape, such as skeletal muscle cells.

Surface area-to-volume ratio

As cells grow, volume increases faster than surface area, limiting exchange with the environment.

Transmission electron microscope (TEM)

Electron microscope that provides high magnification and high resolution of ultrastructure.

Scanning electron microscope (SEM)

Electron microscope that provides three-dimensional surface images.

Cytosol

Fluid and gel-like internal environment of the cell (intracellular fluid, ICF).

Extracellular fluid (ECF)

Fluid outside the cell.

Plasma membrane

Cell boundary composed of a phospholipid bilayer with embedded proteins.

Phospholipid

Major membrane lipid with phosphate heads (hydrophilic) and hydrophobic tails.

Bilayer

Two-layer arrangement of phospholipids forming the cell membrane.

Cholesterol (in membrane)

Membrane lipid (~20%) that modulates fluidity and stability.

Glycolipids

Membrane lipids with carbohydrate portions; contribute to glycocalyx.

Glycocalyx

Carbohydrate-rich external coat on the cell surface; involved in protection and cell recognition (blood types are determined by glycolipids/glycoproteins).

Membrane protein

Proteins that account for about 50% of membrane weight; functions include receptors, channels, enzymes, carriers, and markers.

Transmembrane protein

Proteins that span the lipid bilayer; many are glycoproteins exposed to the extracellular surface.

Glycoprotein

Protein with carbohydrate chains; face the extracellular surface and contribute to glycocalyx.

Peripheral protein

Proteins that adhere to one face of the membrane, often associated with transmembrane proteins.

Receptor

Membrane protein that binds signaling molecules (messengers) to initiate cellular responses.

Second messenger

Small molecule (e.g., cAMP) relayed inside the cell after receptor activation.

G protein

Membrane-associated protein that relays signals from receptor to effectors like adenylate cyclase.

Adenylate cyclase

Enzyme that converts ATP to cyclic AMP (cAMP) in signaling pathways.

Cyclic AMP (cAMP)

Second messenger that activates protein kinases to regulate cellular responses.

Kinase

Enzyme that adds phosphate groups to proteins, altering their activity.

Microvilli

Membrane protrusions that increase surface area; may form a brush border.

Brush border

Dense fringe of microvilli on some absorptive cells; enhances surface area.

Actin

Protein forming microfilaments; provides structural support in microvilli.

Basal body

Anchoring structure for cilia/flagella derived from a centriole.

Cilia

Hairlike extensions; primary cilium is nonmotile and sensory, while motile cilia beat in coordinated waves.

Primary cilium

Nonmotile sensory organelle on many cell types.

Motile cilia

Cilia that beat in a coordinated fashion to move substances across surfaces.

Axoneme

Core structure of a cilium/flagellum with a 9+2 arrangement of microtubules.

Dynein

Motor protein that drives ciliary/flagellar movement using ATP.

Flagella

Long whip-like projections; in humans, only the tail of a sperm cell.

Pseudopod

Cytoplasmic extension used for locomotion and engulfment in phagocytosis.

Endocytosis

Process of taking substances into the cell via vesicles; requires ATP.

Phagocytosis

Cellular eating; engulfing particles into phagosomes that fuse with lysosomes.

Neutrophil

White blood cell that phagocytizes bacteria.

Phagosome

Vesicle formed during phagocytosis that fuses with a lysosome.

Lysosome

Organelle containing digestive enzymes that degrade macromolecules and invaders.

Pinocytosis

Cell drinking; uptake of extracellular fluid and dissolved solutes via endocytosis.

Receptor-mediated endocytosis

Selective uptake of specific molecules via receptor-ligand interactions (clathrin-coated pits).

LDL

Low-density lipoprotein; taken up by receptor-mediated endocytosis to supply cholesterol.

Clathrin

Protein coat on vesicles during receptor-mediated endocytosis.

LDL receptor

Cell-surface receptor that binds LDL for endocytosis.

Endosome

Vesicle formed after endocytosis that sorts cargo for processing.

Transcytosis

Transport of materials across a cell in vesicles from one membrane domain to another.

Exocytosis

Release of material from the cell via vesicle fusion with the plasma membrane.

Vesicle

Membrane-bound sac that transports substances within or outside the cell.

Cytoskeleton

Network of protein filaments and cylinders supporting shape, organization, and movement.

Microfilaments

Thin filaments (about 6 nm) of actin forming the membrane skeleton.

Intermediate filaments

Filaments (8–10 nm) that resist stress and support cell junctions (keratin in epidermis).

Microtubules

25 nm filaments made of tubulin; radiate from centrosome and organize organelles; form cilia/flagella axonemes and mitotic spindle.

Centrosome

Microtubule-organizing center containing a pair of centrioles; essential for cell division.

Nucleus

Largest organelle; contains chromatin and nucleoli; surrounded by a double membrane (nuclear envelope) with pores.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores for transport.

Nuclear pores

Openings in the nuclear envelope that regulate transport of molecules.

Nucleoplasm

Fluid inside the nucleus containing chromatin and nucleoli.

Chromatin

DNA-protein complex that condenses to form chromosomes.

Nucleolus

Nucleolar region where ribosomal RNA (rRNA) synthesis and ribosome assembly occur.

Endoplasmic reticulum (ER)

Membrane network of interconnected sacs; Rough ER bears ribosomes; Smooth ER lacks ribosomes.

Rough ER

ER involved in synthesis of proteins for membranes, organelles, or secretion.

Smooth ER

ER involved in detoxification, lipid/steroid synthesis, and Ca2+ storage.

Ribosomes

RNA-protein complexes that translate mRNA into protein.

Golgi complex

Stack of flattened cisternae that modifies, sorts, and packages proteins for secretion or delivery.

Lysosome (organelle)

Digestive enzyme-containing vesicle that degrades proteins and nucleic acids.

Peroxisome

Organelle that oxidizes organic molecules; produces hydrogen peroxide used in metabolism.

Proteasome

Protein complex that degrades tagged proteins.

Mitochondrion

Organelle that synthesizes ATP; has double membrane with cristae and mtDNA in the matrix.

Crista/Cristea

Folded inner mitochondrial membrane increasing surface area for ATP production.

Matrix

Semi-fluid inside the mitochondrion between cristae containing enzymes and mtDNA.

mtDNA

Mitochondrial DNA, inherited maternally, located in the mitochondrial matrix.

Centriole

Short cylindrical microtubule assembly; part of centrosome and essential for spindle formation.

Centrosome

Region housing a pair of centrioles and organizing microtubules during cell division.

Inclusions

Stored cellular products (e.g., glycogen) or foreign bodies (viruses, dust) not bounded by a membrane.