General Biology - Comprehensive Vocabulary Flashcards

Vocabulary flashcards covering key biological concepts, membrane transport, organic molecules, and cell structures based on course notes.

Fluid Mosaic Model

A model proposed in 1972 by S.J. Singer and G.L. Nicolson describing the cell membrane as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that give it a fluid character.

Amphiphilic

Describing a molecule (such as a phospholipid) that possesses both a hydrophilic (water-attracting) region and a hydrophobic (water-repelling) region.

Integral Proteins

Membrane proteins integrated completely into the lipid bilayer that feature one or more hydrophobic regions composed of nonpolar amino acids.

Peripheral Proteins

Membrane proteins located exclusively on the exterior or interior surfaces of the phospholipid bilayer.

Aquaporins

Specific channel proteins embedded in the cell membrane that facilitate the rapid passive movement of water molecules across the lipid bilayer.

Diffusion

The passive transport process in which a substance moves down its concentration gradient from an area of higher concentration to lower concentration until equilibrium is achieved.

Tonicity

The measure of how an extracellular solution can alter the volume of a cell by affecting osmosis, which directly correlates to the solution's osmolarity.

Osmolarity

The total solute concentration of a solution, comprising both permeable and non-permeable solutes.

Plasmolysis

The phenomenon in walled cells (such as plants) occurring in a hypertonic environment, where the plasma membrane detaches from the cell wall due to water loss.

Primary Active Transport

An active transport mechanism that directly utilizes energy from ATP hydrolysis to move an ion or molecule up its concentration gradient.

Electrogenic Pump

An active transport pump (such as the $\text{Na}^+/\text{K}^+$ pump moving $3\,\text{Na}^+$ out and $2\,\text{K}^+$ in per ATP) that creates a net charge imbalance across the plasma membrane.

Uniporter, Symporter, and Antiporter

Three classes of carrier proteins where Uniporters transport one specific molecule in one direction, Symporters transport two different molecules in the same direction, and Antiporters transport two different molecules in opposite directions.

Secondary Active Transport

A transport process that uses an electrochemical gradient previously established by primary active transport to move a different substance against its concentration gradient without directly consuming ATP.

Phagocytosis

A form of bulk endocytosis ("cellular eating") in which the plasma membrane extends pseudopods to engulf large solid particles, cells, or pathogens into a phagosome vesicle.

Pinocytosis

A form of bulk endocytosis ("cellular drinking") in which the plasma membrane invaginates around a small volume of extracellular fluid and pinches off into a vesicle.

Receptor-Mediated Endocytosis

A highly selective type of bulk transport in which specific target ligands (such as LDL particles) bind to receptors on the membrane surface, triggering clathrin-coated pit invagination.

Exocytosis

The active bulk transport mechanism in which intracellular vesicles containing materials fuse with the plasma membrane to release their contents into the extracellular fluid.

Emergent Properties

New biological properties that arise at higher levels of organization due to the specific arrangement and interactions of simpler constituent parts within a complex system.

Reductionism

The scientific approach of breaking down complex biological systems into simpler components that are more manageable to study.

Systems Biology

An analytical biological approach that constructs dynamic models for the behavior of whole biological systems based on interactions among their components.

Gene Expression

The multi-step process by which information encoded in a gene is converted into a functional cellular product, typically via transcription into RNA and translation into protein.

Natural Selection

The mechanism of evolution described by Charles Darwin where changing environments act on heritable variations within a population, enabling individuals with favorable traits to survive and reproduce.

Adaptations

Favorable inherited characteristics or variations determined by genes that increase an organism's likelihood of surviving and reproducing in its environment.

Three-Domain System

The evolutionary classification system introduced by Carl Woese that categorizes all cellular life into Domain Bacteria, Domain Archaea, and Domain Eukarya.

Structural Isomers

Molecules that share the exact same molecular chemical formula but possess a different covalent arrangement of their atoms.

Geometric Isomers

Isomers (cis-trans) that share identical covalent bonds but differ in the spatial arrangement of atoms around a rigid double C=C bond.

Enantiomers

Molecules that share identical chemical formulas and covalent bonds but differ in 3D spatial orientation, existing as non-superimposable mirror images.

Functional Groups

Specific clusters of atoms within organic molecules that confer consistent chemical properties and reactivity to those molecules.

Condensation Reaction

A chemical reaction (also known as dehydration synthesis) in which two molecules covalently bond together accompanied by the loss of a water molecule.

Hydrolysis

A cleavage reaction requiring water in which a polymer is broken down into smaller monomer units by adding $\text{H}^+$ to one unit and $\text{OH}^-$ to the other.

Glycosidic Linkage

A covalent bond formed between two monosaccharides through a condensation or dehydration reaction.

Ester Linkage

The covalent bond formed between a hydroxyl group of glycerol and the carboxyl group of a fatty acid during fat synthesis.

Saturated Fatty Acid

A hydrocarbon chain that contains no carbon-carbon double bonds, causing the carbon backbone to be saturated with hydrogens and solid at room temperature.

Unsaturated Fatty Acid

A fatty acid containing one or more double C=C bonds in its hydrocarbon backbone, producing kinks that maintain a liquid state (oil) at room temperature.

Trans Fatty Acids

Unsaturated fatty acids resulting from partial hydrogenation that possess double C=C bonds in a trans configuration, straightening the chain and increasing LDL cholesterol risks.

Peptide Bond

The covalent bond formed between the carboxyl group of one amino acid and the amino group of an incoming amino acid via dehydration synthesis.

Four Levels of Protein Structure

The organizational hierarchy of proteins consisting of Primary (amino acid sequence), Secondary ($\alpha$-helices and $\beta$-pleated sheets via backbone H-bonds), Tertiary (3D folding via R-group interactions), and Quaternary (assembly of multiple polypeptide chains).

Denaturation

A process in which changes in pH, temperature, or chemical conditions alter a protein's structure and shape, leading to a loss of biological function.

Nucleotide

The monomer building block of nucleic acids, consisting of a nitrogenous base (purine or pyrimidine), a pentose sugar (ribose or deoxyribose), and one or more phosphate groups.

Central Dogma of Molecular Biology

The fundamental framework articulated by Francis Crick stating that sequential genetic information transfers from DNA replication to transcription into RNA, and translation into protein.

Magnification

The measure or process of enlarging an object's appearance relative to its actual physical size.

Resolving Power

The capacity of a microscope to distinguish two adjacent structures as separate, determining the clarity and detail of an image.

Prokaryotic Cell

A simpler, smaller, single-celled organism (Domain Bacteria or Archaea) that lacks a membrane-bound nucleus and internal membrane-enclosed organelles.

Nucleoid

The central, non-membrane-bound region within a prokaryotic cell where the circular chromosomal DNA is concentrated.

Peptidoglycan

A polymer component forming the cell wall of most bacteria that provides structural support and is targeted by antibiotics like penicillin.

Endomembrane System

A group of interconnected internal membranes and organelles in eukaryotic cells (nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, and plasma membrane) that synthesize, modify, package, and transport cell materials.

Rough Endoplasmic Reticulum

A region of the endomembrane system studded with ribosomes on its cytoplasmic surface that modifies proteins and synthesizes membrane phospholipids.

Smooth Endoplasmic Reticulum

A region of the endoplasmic reticulum lacking ribosomes that synthesizes carbohydrates, lipids, and steroid hormones, detoxifies poisons, and stores calcium ions ($\text{Ca}^{2+}$).

Golgi Apparatus

An organelle consisting of flattened membranous sacs (cisternae) featuring a receiving cis face and shipping trans face that sorts, tags, and packages proteins and lipids.

Lysosomes

Membrane-bound vesicles in animal cells filled with digestive enzymes used to break down macromolecules, worn-out organelles, and ingested pathogens.

Mitochondrial Structure

An organelle featuring an outer membrane, an inner membrane folded into cristae to maximize surface area for ATP synthesis, and an internal fluid-filled matrix.

Endosymbiotic Theory

The hypothesis championed by Lynn Margulis proposing that eukaryotic mitochondria and chloroplasts originated as independent prokaryotic organisms engulfed by ancestral cells.

Plasmodesmata

Microscopic channels passing through plant cell walls that connect the cytoplasm of adjacent cells and allow transport of materials.

Tight Junctions

Watertight intercellular seals between animal epithelial cells that prevent liquid and solute leakage between adjacent cell layers.

Desmosomes

Intercellular junctions formed by cadherin proteins that act like spot welds to attach adjacent animal cells in tissues subject to stretching.

Gap Junction

An intercellular channel in animal cells created by six connexin proteins forming a doughnut-like connexon structure, allowing ions and small molecules to pass directly between adjacent cells.