Chapter 3: Cell Structures and Their Functions

Vocabulary flashcards covering key terms from Chapter 3: Cell Structures and Their Functions.

Nucleus

Organelle containing the cell's genetic material; site of DNA storage and RNA synthesis; contains the nucleolus.

Nucleolus

Dense region within the nucleus where ribosomal subunits are assembled (rRNA).

Nuclear envelope

Double membrane surrounding the nucleus that encloses its contents.

Nuclear pore

Protein channels in the nuclear envelope allowing transport between the nucleus and cytoplasm.

Chromosomes

DNA-protein complexes carrying genetic information; 23 pairs in humans; visible as chromatids during division.

Chromatin

Loosely coiled DNA and proteins in the nondividing cell, accessible for transcription.

DNA

Deoxyribonucleic acid; genetic material; uses thymine; stored in the nucleus.

RNA

Ribonucleic acid; single-stranded; includes mRNA, tRNA, and rRNA; uses uracil.

Messenger RNA (mRNA)

Copy of a gene that travels from the nucleus to ribosomes to guide protein synthesis.

Transfer RNA (tRNA)

RNA that carries amino acids to ribosomes; contains anticodons.

Ribosomal RNA (rRNA)

RNA component of ribosomes; helps assemble amino acids into proteins.

Ribosome

Site of protein synthesis; can be free in cytoplasm or attached to rough ER.

Free ribosome

Ribosome suspended in cytoplasm; synthesizes cytosolic and organelle-targeted proteins.

Rough endoplasmic reticulum (RER)

ER with ribosomes; synthesizes proteins destined for secretion or membranes.

Smooth endoplasmic reticulum (SER)

ER lacking ribosomes; lipid synthesis, detoxification, and calcium storage.

Golgi apparatus

Stacks of membranes that modify, package, and distribute proteins and lipids; forms secretory vesicles.

Secretory vesicle

Vesicle that stores and transports secreted products to the cell membrane for exocytosis.

Lysosome

Organelle with digestive enzymes for intracellular breakdown of material.

Peroxisome

Vesicle containing enzymes that break down fatty acids and detoxify; produce hydrogen peroxide.

Mitochondrion

Powerhouse of the cell; site of aerobic respiration and ATP synthesis; contains cristae and matrix.

Cristae

Folded inner membrane folds of mitochondria that increase surface area for ATP production.

Mitochondrial matrix

Fluid-filled space inside the inner membrane containing enzymes and mtDNA.

Cytoplasm

Living material between the nucleus and plasma membrane; contains organelles.

Cytoskeleton

Internal framework of the cell that supports shape, positions organelles, and enables movement.

Microtubule

Hollow protein tubes; part of the cytoskeleton; participate in cell division and form cilia/flagella.

Microfilament

Thin filaments (actin) supporting cytoplasm and enabling cell movement and shape changes.

Intermediate filament

Filaments providing mechanical support; keratin is a common example.

Centriole

Cylindrical organelles that organize spindle fibers during cell division.

Centrosome

Region near the nucleus where microtubule organizing center is located; contains two centrioles.

Cilia

Short, hairlike projections on many cell surfaces that move substances over cell surfaces.

Flagellum

Long projection (usually one per cell) that propels the cell, as in sperm.

Microvilli

Extensive membrane folds supported by actin filaments that increase surface area.

Cell membrane (plasma membrane)

Outer boundary of the cell; phospholipid bilayer with proteins and cholesterol; selectively permeable.

Phospholipid bilayer

Two-layer arrangement of phospholipids forming the basic structure of the cell membrane; hydrophilic heads face water; hydrophobic tails hide inside.

Cholesterol

Sterol in the membrane that increases stability and modulates fluidity.

Integral membrane protein

Proteins that span the lipid bilayer; function as channels, transporters, receptors, or enzymes.

Peripheral membrane protein

Proteins attached to the inner or outer surface of the membrane; do not span the bilayer.

Glycoprotein

Protein with carbohydrate chains; part of the glycocalyx; acts as a cell-surface marker.

Glycolipid

Lipid with attached carbohydrate; contributes to the glycocalyx.

Glycocalyx

Carbohydrate-rich coating on the cell surface formed by glycolipids and glycoproteins.

Diffusion

Movement of solutes from higher to lower concentration due to random motion.

Osmosis

Diffusion of water across a selectively permeable membrane from higher to lower water concentration.

Isotonic

Solution with equal solute concentration on both sides of the membrane; no net water movement.

Hypotonic

Solution with lower solute concentration outside the cell; water moves in, possibly causing swelling.

Hypertonic

Solution with higher solute concentration outside the cell; water moves out, causing shrinkage.

Carrier-mediated transport

Transport of large or charged molecules via carrier proteins; highly specific and may be active or passive.

Primary active transport

Movement of substances against their concentration gradient using ATP (e.g., Na+/K+ pump).

Secondary active transport

Transport driven by an ion gradient established by primary active transport; includes cotransport (symport) and antiport (antiport).

Facilitated diffusion

Carrier-mediated diffusion down a concentration gradient; no ATP required.

Endocytosis

Process of taking material into the cell via vesicle formation.

Exocytosis

Process of releasing material from the cell via vesicle fusion with the membrane.

Phagocytosis

Endocytosis of solid particles; cell eating.

Pinocytosis

Endocytosis of extracellular fluid and small solutes; cell drinking.

Na+/K+ pump

Sodium-potassium ATPase; pumps Na+ out and K+ in to maintain resting potential.

Diploid

Cell containing two sets of chromosomes (2n); in humans, 46 in somatic cells.

Haploid

Cell containing one set of chromosomes (n); gametes have 23 in humans.

Autosomes

The 22 pairs of chromosomes that are not sex chromosomes.

Sex chromosome

Chromosome pair determining sex (X and Y in humans).