Cell Structure, Membrane Transport, and Cellular Communication Review

Comprehensive vocabulary flashcards covering cell organelles, membrane structure, cellular transport mechanisms, signaling pathways, and microscopy.

Aquaporins

Specialized transmembrane channel proteins through which water moves rapidly across cell membranes.

Turgor Pressure

Positive pressure generated against the plant cell wall when a plant cell in an extremely hypotonic environment takes in water by osmosis, causing the central vacuole to expand.

Sodium-Potassium Exchange

The active pumping of sodium ions ($\text{Na}^+$) out of the cell against their concentration gradient using energy derived from ATP hydrolysis.

Membrane Potential

The electrical voltage or charge differential across a biological membrane.

Electrochemical Gradient

The combined electrical force (membrane potential) and chemical force (concentration gradient) driving the movement of ions across membranes.

Proton Pumps

Transport proteins that actively move hydrogen ions ($\text{H}^+$) across membranes using ATP to create a proton concentration gradient for regulating cytoplasmic pH and powering secondary active transport.

Phagocytosis

A form of endocytosis in which a cell engulfs large particles or whole cells.

Receptor-Mediated Endocytosis

A selective form of endocytosis where exterior plasma membrane receptor proteins bind specific ligands and orient toward the interior surface of the vesicle upon internalization.

Stages of Cell Signaling

A three-stage pathway consisting of signal reception, signal transduction, and cellular response.

Ligand

A specific signal molecule that selectively binds to a larger receptor protein to initiate a cellular cascade.

Integrins

Transmembrane receptor proteins used by the extracellular matrix to transmit external chemical and mechanical signals to the interior of the cell.

Gap Junctions

Direct channels between adjacent cells that permit ions and small soluble molecules to pass directly from the cytoplasm of one cell to another.

Phagocytes

White blood cells used as model systems for studying lysosomes because they actively engulf, absorb, and degrade bacterial pathogens via lysosomal enzymes.

Transmembrane (Integral) Proteins

Membrane proteins that span across the hydrophobic core of the phospholipid bilayer.

Peripheral Proteins

Membrane appendages that adhere to the outer or inner surface of the bilayer without embedding into the hydrophobic core.

Membrane-Bound Glycoproteins

Molecules that function as cell-surface receptors and play a critical role in cell-to-cell recognition.

Amphipathic Phospholipid Bilayer

A membrane arrangement where hydrophilic heads face internal/external aqueous environments and hydrophobic fatty acid tails are shielded inside, allowing lateral movement of lipids and proteins.

Diffusion

A passive transport process that moves substances down their concentration gradient (from high to low concentration) without cellular energy (ATP).

Active Transport

The movement of substances against their concentration gradient (from low to high concentration) requiring cellular energy (ATP).

Facilitated Diffusion

The movement of substances across membrane proteins without direct energy input, driven against their concentration or electrochemical gradient as described in the notes.

Cristae

Folds of the inner mitochondrial membrane that maximize surface area for ATP production and metabolic processes.

Chloroplast Components

The three primary structural components of chloroplasts: grana (stacks of thylakoids), thylakoids, and the fluid stroma.

Organellar DNA Distribution

The storage pattern where genomic DNA is kept in the nucleus, but plant cells additionally store organellar DNA in mitochondria and chloroplasts, whereas animal cells store it only in mitochondria.

Centrioles

Microtubule-based organelles that share a structural microtubule arrangement similar to basal bodies.

Cilia and Flagella

Cellular motility structures composed of microtubules (organized by centrosomes) that drive movement through back-and-forth and side-to-side motions.

Cell Wall

A rigid outer layer present in plants, fungi, bacteria, archaea, algae, and protists that provides structural support and maintains turgor pressure.

Proteoglycans

Complex molecules of proteins and carbohydrates synthesized by coordinated processes of the ER and Golgi apparatus that form a major structural component of the extracellular matrix.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids, attaches carbohydrate chains to proteoglycans, and synthesizes ECM carbohydrates.

Cell Fractionation

A laboratory procedure that separates major cellular organelles based on size and density to isolate and determine their individual functions.

Smooth Endoplasmic Reticulum (SER)

An organelle abundant in liver cells that synthesizes lipids (oils, phospholipids, steroids) and detoxifies harmful drugs (e.g., phenobarbital) into water-soluble substances excreted in urine.

Rough Endoplasmic Reticulum (RER)

An organelle studded with bound ribosomes specialized in synthesizing membrane proteins and proteins destined for export (secretion).

Lysosomes

Membrane-bound organelles containing hydrolytic enzymes that digest waste, macromolecules, and foreign bacterial pathogens.

Endosymbiotic Theory

The evolutionary model proposing that mitochondria and chloroplasts evolved from ancestral prokaryotes engulfed by early eukaryotic cells, evidenced by their circular DNA and ribosomes.