BIOL 105: Unifying Biology Themes, Membrane Structure & Transport, and Cell Signaling

Vocabulary practice flashcards covering core biological concepts, scientific experimentation, membrane structure and transport, and cellular signaling mechanisms from General Biology 105.

Emergent Properties

New properties that arise at successive levels of biological organization due to the arrangement and interactions of parts as complexity increases.

Cell

The smallest fundamental unit of life capable of performing all required life functions.

Evolution

The process of biological change in which species accumulate differences from their ancestors over time, accounting for both the unity and diversity of life.

Three Domains of Life

The three overarching taxonomic categories of organisms: Domain Bacteria, Domain Archaea, and Domain Eukarya.

Controlled Experiment

An experimental setup designed to compare an experimental group with a control group that acts as a standard for comparison.

Independent Variable

The specific factor that is manipulated or changed by researchers in an experiment.

Dependent Variable

The factor that is measured to see the effect or outcome produced by manipulating the independent variable.

Peromyscus polionotus

The species of mouse studied by Francis B. Sumner and Hopi Hoekstra to demonstrate how coat coloration adaptation provides camouflage against visual predators in beach versus inland habitats.

Amphipathic Molecule

A molecule that possesses both hydrophobic (water-fearing) and hydrophilic (water-loving) regions, such as a membrane phospholipid.

Fluid Mosaic Model

A structural model of the plasma membrane describing it as a fluid bilayer of phospholipids with various protein molecules embedded in or attached to it, moving laterally.

Selective Permeability

The quality of a biological membrane that allows some molecules or ions to pass through easily while restricting others.

Integral Proteins

Membrane proteins that penetrate into the hydrophobic core of the lipid bilayer.

Peripheral Proteins

Membrane proteins that are loosely bound to the outer or inner surface of the plasma membrane rather than embedded in the hydrophobic interior.

Channel Proteins

Transport proteins that provide hydrophilic corridors or tunnels across the cell membrane for specific molecules or ions.

Carrier Proteins

Transport proteins that bind to specific target molecules and undergo conformational shape changes to shuttle them across the membrane.

Aquaporins

Specialized channel proteins embedded in cell membranes that greatly accelerate the passage of water molecules.

Passive Transport

The diffusion of a substance across a biological membrane down its concentration gradient without requiring expenditure of cellular energy.

Diffusion

The movement of particles of a substance so that they spread out evenly into available space, moving from an area of higher concentration to lower concentration.

Osmosis

The diffusion of free water molecules across a selectively permeable membrane from an area of lower solute concentration to higher solute concentration.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Isotonic Solution

A surrounding solution whose solute concentration is equal to the concentration inside the cell, resulting in no net movement of water across the membrane.

Hypertonic Solution

A surrounding solution with a higher solute concentration than inside the cell, causing net water loss and causing cells to shrivel or plasmolyze.

Hypotonic Solution

A surrounding solution with a lower solute concentration than inside the cell, causing net water uptake and making cells swell or lyse.

Plasmolysis

The phenomenon in plant cells placed in a hypertonic solution where the cytoplasm shrivels and the plasma membrane pulls away from the rigid cell wall.

Active Transport

The movement of a substance across a cell membrane against its concentration gradient (from low to high concentration), requiring cellular energy in the form of $\text{ATP}$ and transport proteins.

Sodium-Potassium Pump

A specialized active transport carrier protein that hydrolyzes $\text{ATP}$ to pump three $\text{Na}^+$ ions out of the cell for every two $\text{K}^+$ ions pumped into the cell.

Exocytosis

A form of bulk transport in which large molecules or waste products are secreted outside the cell when intracellular vesicles fuse with the plasma membrane.

Endocytosis

A form of bulk transport in which large molecules or extracellular materials are taken into the cell by forming new vesicles pinched inward from the plasma membrane.

Phagocytosis

A form of endocytosis known as cellular eating, where a cell extends pseudopodia around a large particle or microorganism to package it inside a food vacuole.

Pinocytosis

A form of endocytosis known as cellular drinking, where a cell non-specifically pinches inward to engulf small droplets of extracellular fluid into coated vesicles.

Receptor-Mediated Endocytosis

A specialized type of endocytosis where specific target solutes (ligands) bind to receptor proteins on the membrane surface, triggering vesicle formation to uptake specific substances.

Paracrine Signaling

A form of local cell signaling in which a sending cell secretes local regulator molecules into extracellular fluid to act on neighboring target cells.

Synaptic Signaling

A specialized form of local cell signaling occurring in animal nervous systems where an electrical signal triggers neurotransmitter release across a synaptic gap to a target cell.

Endocrine Signaling

A long-distance cell signaling mechanism where specialized endocrine cells secrete hormones into body fluids, such as the bloodstream, to reach distant target cells.

Ligand

A chemical signaling molecule that specifically binds to a larger receptor protein, typically altering receptor shape and function.

Cell-Surface Receptors

Receptor proteins located on the plasma membrane that bind large or hydrophilic signaling molecules that cannot diffuse across the hydrophobic core of the cell membrane.

Intracellular Receptors

Receptor proteins found inside the cytoplasm or nucleus of target cells that bind small or hydrophobic signaling molecules that cross the plasma membrane.

Signal Transduction Pathway

A multi-step cascade of molecular changes in relay molecules inside a cell initiated by ligand binding to a receptor, leading to a specific cellular response.

Protein Kinase

An enzyme that transfers a phosphate group from $\text{ATP}$ to a substrate protein (phosphorylates it), altering protein shape and activity.

Protein Phosphatase

An enzyme that removes phosphate groups from phosphorylated proteins (dephosphorylates them) using $\text{H}_2\text{O}$, turning off signal transduction pathways.