General Biology: Comprehensive Lecture Review

Vocabulary practice flashcards covering general biology concepts from Sessions 1 through 7, including chemistry of life, macromolecules, cellular anatomy, membrane transport, cell signaling, metabolism, and cellular respiration.

Biology

The study of life across multiple hierarchical levels, ranging from molecules to ecosystems.

Matter

Anything that takes up space, has mass, and is composed of chemical elements.

Elements

Substances that cannot be broken down into other substances by chemical means.

Compounds

Substances consisting of two or more elements combined in a fixed ratio, typically exhibiting emergent properties.

Essential Elements

The four chemical elements—carbon, hydrogen, oxygen, and nitrogen ($C, H, O, N$)—that make up $96\%$ of living matter.

Covalent Bonds

Stable chemical bonds formed between atoms whose electronegativity difference is small or stable.

Polar Covalent Bonds

Unstable chemical bonds where electronegativity is unevenly distributed between bonded atoms.

Cohesion

The phenomenon whereby hydrogen bonds hold water molecules together.

Adhesion

The attraction of water molecules to other distinct substances.

Buffers

Substances present in blood and other biological fluids that stabilize and maintain a relatively constant $\text{pH}$ despite the addition of acids or bases.

Isomers

Compounds that have the same chemical formula but distinct structural arrangements and properties, including structural isomers, cis-trans isomers, and enantiomers.

ATP (Adenosine Triphosphate)

The primary energy-carrying molecule of the cell, which powers cellular work.

Macromolecules

Large, complex biological molecules built from repeating smaller subunits, including carbohydrates, proteins, and nucleic acids.

Monomers

Small chemical units that serve as the fundamental building blocks of polymers.

Polymers

Long molecules consisting of many similar or identical building blocks connected by covalent bonds.

Dehydration Reaction

A chemical reaction that covalently connects monomers to synthesize a polymer through the removal of a water molecule ($H_2O$).

Hydrolysis

A chemical process that disassembles polymers into monomers through the addition of a water molecule ($H_2O$).

Monosaccharides

Simple sugars that have molecular formulas with multiples of $(CH_2O)$, containing a carbonyl group ($C=O$) and multiple hydroxyl groups ($-OH$).

Disaccharides

Double sugars formed by joining two monosaccharides together through a dehydration reaction that produces a glycosidic linkage.

Cellulose

A structural polysaccharide made of glucose monomers with alternating bonds that forms tough microfibrils in plant cell walls and cannot be digested by humans.

Chitin

A structural polysaccharide with a nitrogen group, found in fungal cell walls and the exoskeletons of crustaceans and insects.

Lipids

A diverse class of hydrophobic biological molecules made primarily of hydrocarbons that do not form true polymers.

Saturated Fats

Fats lacking carbon-carbon double bonds in their fatty acid chains, forming straight structures that are solid at room temperature.

Unsaturated Fats

Fats containing one or more double bonds in their fatty acid chains, producing bent hydrocarbon tails that remain liquid at room temperature.

Phospholipids

Lipids composed of a glycerol backbone bonded to two hydrophobic fatty acid tails and a hydrophilic phosphate head, forming membrane bilayers.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings, such as cholesterol and steroid hormones.

Amino Acids

Organic molecules serving as the monomers of proteins, each containing an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and a variable R group.

Primary Structure

The linear sequence of amino acids in a polypeptide chain, encoded directly by genetic information.

Secondary Structure

Coils and folds in a polypeptide backbone resulting from hydrogen bonding, forming an $\alpha\text{-helix}$ or a $\beta\text{-sheet}$.

Tertiary Structure

The overall three-dimensional shape of a polypeptide chain determined by interactions among R groups, including hydrophobic interactions, ionic bonds, and disulfide bridges.

Quaternary Structure

The overall protein conformation resulting from the aggregation of two or more individual polypeptide chains.

Denaturation

The loss of a protein's native three-dimensional conformation and biological activity caused by environmental changes in $\text{pH}$, salt concentration, or temperature.

Chaperonins

Helper protein complexes that assist in the proper folding of other proteins within the cell.

Nucleotide

The structural monomer of nucleic acids, consisting of a nitrogenous base, a five-carbon sugar, and a phosphate group.

Prokaryotic Cells

Cells lacking a membrane-enclosed nucleus and membrane-bound organelles, typically measuring $1\text{--}5\,\mu\text{m}$ with DNA located in a nucleoid.

Eukaryotic Cells

Cells with a membrane-enclosed nucleus containing genetic material and membrane-bound organelles, typically measuring $10\text{--}100\,\mu\text{m}$.

Nucleolus

A dense structure within the eukaryotic nucleus responsible for synthesizing $\text{rRNA}$ and assembling ribosomes.

Rough Endoplasmic Reticulum

A region of the endoplasmic reticulum studded with ribosomes that synthesizes proteins destined for membranes, organelles, or secretion.

Smooth Endoplasmic Reticulum

A region of the endoplasmic reticulum devoid of ribosomes that synthesizes lipids and detoxifies drugs and poisons.

Golgi Apparatus

An organelle of flattened membranous sacs that receives products at its cis face, modifies and stores them, and ships them from its trans face.

Lysosomes

Membranous sacs containing hydrolytic digestive enzymes that break down macromolecules, foreign matter, and damaged organelles (autophagy) in acidic conditions.

Extracellular Matrix (ECM)

A structural meshwork outside animal cells composed of collagen fibers, proteoglycans, and fibronectin attached to membrane integrins.

Plasmodesmata

Microscopic membrane-lined channels running through plant cell walls that connect the cytoplasm of adjacent cells to transport water and solutes.

Fluid Mosaic Model

A model describing biological membranes as flexible mosaics of various proteins dispersed laterally within a fluid phospholipid bilayer.

Amphipathic

Molecules that contain both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Selective Permeability

A property of cellular membranes allowing certain nonpolar molecules to cross freely while restricting ions and large polar molecules.

Osmosis

The passive diffusion of free water across a selectively permeable membrane toward a region of higher solute concentration.

Active Transport

The movement of a substance across a membrane against its concentration gradient, requiring energy expenditure from ATP and carrier proteins.

Sodium-Potassium Pump

A membrane transport protein that uses ATP to actively pump $3\,\text{Na}^+$ ions out of animal cells and $2\,\text{K}^+$ ions into the cell.

Phagocytosis

A form of endocytosis ('cell eating') in which a cell engulfs solid particulate matter into a food vacuole.

Pinocytosis

A form of endocytosis ('cell drinking') where a cell non-specifically gulps droplets of extracellular fluid into small vesicles.

Paracrine Signalling

A form of local cellular communication where a secreting cell discharges local regulator molecules into extracellular fluid to influence adjacent target cells.

G Protein-Coupled Receptors (GPCRs)

Plasma membrane signal receptor proteins that activate associated G proteins by binding GTP upon extracellular ligand stimulation.

Protein Kinases

Enzymes that catalyze the transfer of phosphate groups from ATP to proteins during signal transduction cascades.

Protein Phosphatases

Enzymes that rapidly dephosphorylate proteins by removing phosphate groups, shutting off signal transduction pathways.

Apoptosis

Programmed and organized cell death that disassembles damaged or infected cells safely into membrane-bound vesicles without harming adjacent tissue.

Metabolism

The totality of all chemical reactions occurring within a living organism, organized into defined metabolic pathways.

Free Energy ($\Delta G$)

The portion of a biological system's energy capable of performing work when temperature and pressure remain uniform.

Exergonic Reaction

A spontaneous chemical reaction characterized by a negative change in free energy ($\Delta G < 0$) that proceeds with a net release of energy.

Endergonic Reaction

A non-spontaneous chemical reaction characterized by a positive change in free energy ($\Delta G > 0$) that requires an input of energy.

Energy Coupling

The use of energy released by an exergonic process (such as ATP hydrolysis) to drive an endergonic chemical process.

Activation Energy ($E_A$)

The initial amount of energy needed to start a chemical reaction, which is lowered by catalytic enzymes.

Competitive Inhibitors

Substances that reduce enzyme activity by competing directly with substrate molecules for binding at the active site.

Non-Competitive Inhibitors

Substances that decrease enzyme activity by binding to a location away from the active site, inducing a conformational change that alters active site functionality.

Feedback Inhibition

A metabolic regulatory mechanism where the terminal product of a biosynthetic pathway allosterically inhibits an early enzyme in that pathway.

Aerobic Respiration

A catabolic pathway that uses oxygen as the final electron acceptor in an electron transport chain to completely break down organic fuel and generate ATP.

Glycolysis

A cytoplasmic pathway that breaks down glucose into two molecules of pyruvate, generating a net gain of $2\,\text{ATP}$ and $2\,\text{NADH}$ with or without oxygen.

Citric Acid Cycle

A mitochondrial metabolic cycle that oxidizes acetyl CoA derived from pyruvate, yielding $4\,CO_2$, $6\,\text{NADH}$, $2\,\text{FADH}_2$, and $2\,\text{ATP}$ per glucose.

Oxidative Phosphorylation

The production of ATP via electron transport chain redox reactions coupled to chemiosmosis, accounting for approximately $90\%$ of cellular ATP generation.

ATP Synthase

A membrane-bound enzyme complex that uses the energy of an $H^+$ electrochemical gradient to synthesize ATP from ADP and inorganic phosphate.

Fermentation

A catabolic process that enables continuous ATP generation by glycolysis in the absence of oxygen through regenerating $\text{NAD}^+$ without an electron transport chain.