Chapter Three

Cytosol

Fluid component of the cytoplasm excluding organelles.

Cytoplasm

Contents of the cell excluding the nucleus.

Selective Barrier

Regulates passage in and out of the cell.

Phospholipid Bilayer

Two-layered structure of cell membranes.

Cholesterol

Maintains fluidity in the plasma membrane.

Integral Membrane Proteins

Proteins that span the entire membrane.

Transmembrane Proteins

Integral proteins that cross the membrane completely.

Peripheral Membrane Proteins

Proteins attached to membrane surface, not embedded.

Fluid-Mosaic Model

Describes the dynamic nature of cell membranes.

Integrins

Transmembrane proteins linking cells to the extracellular matrix.

Desmosomes

Anchoring junctions connecting adjacent cells.

Tight Junctions

Prevent passage between adjacent cells.

Gap Junctions

Channels allowing communication between adjacent cells.

Nucleus

Stores and transmits genetic information.

Chromatin

DNA complexed with proteins, forms chromosomes during division.

Nuclear Envelope

Double membrane surrounding the nucleus.

Ribosomes

Sites of protein synthesis, composed of RNA and proteins.

Rough ER

Endoplasmic reticulum with ribosomes, synthesizes proteins.

Smooth ER

Lacks ribosomes, synthesizes lipids and detoxifies.

Golgi Apparatus

Modifies and sorts proteins for transport.

Mitochondria

Powerhouse of the cell, site of ATP production.

Lysosomes

Digestive vesicles breaking down waste materials.

Peroxisomes

Break down fatty acids and detoxify harmful substances.

Cytoskeleton

Network of filaments maintaining cell shape and movement.

Actin Filaments

Microfilaments involved in cell movement and shape.

Intermediate Filaments

Provide mechanical support and strength to cells.

Microtubules

Tubulin-based structures aiding in organelle movement.

Cilia

Hair-like structures aiding in cell movement.

Gene

DNA sequence specifying amino acid sequence.

Triplet Code

64 codons specify amino acids in proteins.

Ligand

Molecule that binds to a protein.

Affinity

Strength of ligand-protein binding interaction.

Enzymes

Proteins that catalyze biochemical reactions.

Glycolytic Pathway

Breaks down glucose into pyruvate, yielding ATP.

Krebs Cycle

Oxidizes Acetyl CoA, producing NADH and CO2.

Electron Transport Chain

Uses electrons to generate ATP and water.