The Science of Biology and Cell Structure Vocabulary Flashcards

Comprehensive vocabulary flashcards covering key biological concepts, chemical foundations, biological macromolecules, and cellular structures from Chapters 1 through 4.

Cell Theory

The fundamental biological principle stating that all organisms are composed of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Emergent Properties

Novel properties that result from the interactions of lower-level components and cannot be deduced solely by examining individual parts in isolation.

Deductive Reasoning

A form of logical thinking that uses established general principles to make specific predictions.

Inductive Reasoning

A form of logical thinking that uses specific individual observations to construct general scientific conclusions.

Hypothesis

A suggested, testable explanation for an observation that makes testable predictions and can be changed or refined with new data.

Reductionism

A philosophical approach in science that breaks a complex biological process down into its simpler, individual component parts.

Systems Biology

An approach to biology focusing on understanding emergent properties that cannot be understood by examining simpler isolated components alone.

Scientific Theory

A comprehensive body of interconnected concepts supported by extensive experimental evidence and scientific reasoning.

Natural Selection

The evolutionary mechanism proposed by Charles Darwin in which differential survival and reproduction lead to adaptation and evolutionary change.

Homologous Structures

Anatomical structures in different species that share a common evolutionary origin, even if they currently differ in structure and function.

Analogous Structures

Anatomical structures in different species that serve a similar function but do not share a common evolutionary origin.

Phylogenetic Tree

A branching diagram used to reconstruct evolutionary history by tracing the origin of specific genetic changes across organisms.

Element

Any substance that cannot be broken down into other substances by ordinary chemical means.

Atomic Number

The total number of protons contained within the nucleus of an atom of a specific element.

Atomic Mass

The combined total mass of protons and neutrons in an atom, measured in Daltons ($\text{Da}$).

Isotopes

Atoms of a single element that possess the same number of protons but different numbers of neutrons.

Half-Life

The constant period of time required for one-half of the radioactive atoms in a sample to decay.

Cation

An atom or molecule with a net positive electrical charge resulting from having more protons than electrons.

Anion

An atom or molecule with a net negative electrical charge resulting from having fewer protons than electrons.

Oxidation

The chemical process during a reaction in which an atom or molecule loses one or more electrons.

Reduction

The chemical process during a reaction in which an atom or molecule gains one or more electrons.

Valence Electrons

Electrons located in the outermost energy level of an atom that dictate its chemical reactivity.

Octet Rule

The principle stating that atoms tend to gain, lose, or share electrons to establish a completely full outer shell of $8$ valence electrons.

Electronegativity

A measure of an atom's affinity or structural pull for shared electrons in a covalent bond.

Nonpolar Covalent Bond

A covalent bond formed by the equal sharing of electrons between atoms with similar electronegativity.

Polar Covalent Bond

A covalent bond formed by the unequal sharing of electrons due to differences in electronegativity, creating partial charges ($\text{δ}^+$ and $\text{δ}^-$).

Cohesion

The attraction between water molecules that causes them to stick to one another via hydrogen bonding.

Adhesion

The attraction of water molecules to other polar molecules via hydrogen bonding.

Specific Heat

The amount of heat required to change the temperature of a given mass of a substance by $1\,^{\circ}\text{C}$.

Heat of Vaporization

The amount of energy required to convert a liquid into a gas, providing cooling when water evaporates from a surface.

Hydrophilic

Polar or charged substances that readily dissolve in or interact with water ("water-loving").

Hydrophobic

Nonpolar substances that do not dissolve in water and aggregate together in aqueous solutions ("water-fearing").

Buffer

A substance that resists changes in pH by releasing hydrogen ions ($\text{H}^+$) when a base is added or absorbing them when an acid is added.

Structural Isomers

Molecules with identical empirical formulas that differ in the physical structure of their carbon skeleton.

Stereoisomers

Molecules with identical empirical formulas and carbon skeletons that differ in how functional groups are oriented in 3D space.

Enantiomers

Chiral stereoisomers that are non-superimposable mirror images of each other.

Dehydration Synthesis

A chemical reaction that joins monomers into larger polymers by removing a molecule of water ($\text{H}_2\text{O}$).

Hydrolysis

A chemical reaction that breaks polymers down into monomer subunits by adding a molecule of water ($\text{H}_2\text{O}$).

Monosaccharide

The simplest carbohydrate subunit consisting of a single sugar molecule, such as glucose ($\text{C}_6\text{H}_{12}\text{O}_6$).

Polysaccharide

A long polymer chain composed of monosaccharide subunits linked together through dehydration synthesis.

Phosphodiester Bond

The covalent linkage connecting the phosphate group of one nucleotide to the sugar molecule of an adjacent nucleotide in nucleic acids.

Peptide Bond

The covalent bond formed between the carboxyl end of one amino acid and the amino end of another during protein synthesis.

Primary Structure

The specific linear amino acid sequence of a polypeptide chain.

Secondary Structure

Regular repeating structures in a polypeptide backbone, such as $\alpha$-helices and $\beta$-pleated sheets, stabilized by hydrogen bonding.

Tertiary Structure

The overall final three-dimensional folded shape of a single globular polypeptide chain.

Quaternary Structure

The structural arrangement formed when a functional protein is composed of two or more distinct polypeptide chains (subunits).

Motif

A common structural combination of secondary structures found across many different polypeptide chains.

Domain

A distinct functional unit within a larger protein structure that performs a specific aspect of the protein's overall function.

Chaperone Proteins

Specialized proteins that assist newly synthesized or misfolded proteins in adopting their correct three-dimensional shape.

Denaturation

The loss of a protein's three-dimensional shape and function caused by altered environmental conditions such as pH, temperature, or ion concentration.

Triglyceride

A lipid molecule composed of one glycerol molecule bonded to three fatty acid chains.

Phospholipid

An amphipathic lipid consisting of glycerol, two nonpolar fatty acid tails, and a polar phosphate head group.

Phospholipid Bilayer

A two-layered sheet of phospholipids with hydrophilic heads facing outward toward water and hydrophobic tails pointing inward.

Prokaryotic Cells

Simple organisms lacking a membrane-bound nucleus and internal membrane-bound organelles.

Eukaryotic Cells

Complex cells characterized by compartmentalization, possessing a membrane-bound nucleus and organelle systems.

Peptidoglycan

A carbohydrate-protein polymer forming the rigid cell wall surrounding most bacterial cells.

Nucleolus

A specialized region within the eukaryotic nucleus where ribosomal RNA (rRNA) synthesis takes place.

Nuclear Envelope

The double-membrane structure composed of two phospholipid bilayers that surrounds the eukaryotic nucleus.

Ribosomes

Cellular structures composed of ribosomal RNA (rRNA) and proteins that carry out protein synthesis in all living cells.

Rough Endoplasmic Reticulum

An internal membrane system studded with ribosomes involved in synthesizing proteins destined for secretion, membranes, or lysosomes.

Smooth Endoplasmic Reticulum

An internal membrane network lacking ribosomes, involved in lipid synthesis, carbohydrate metabolism, and detoxification.

Golgi Apparatus

A collection of flattened membranous stacks (cisternae) that packages, modifies, and distributes molecules within or outside the cell.

Lysosomes

Membrane-bounded digestive vesicles arising from the Golgi apparatus that contain hydrolytic enzymes to break down macromolecules and old organelles.

Peroxisomes

Microbodies containing enzymes that oxidize fatty acids, producing hydrogen peroxide ($\text{H}_2\text{O}_2$) which is converted to harmless byproducts by catalase.

Central Vacuole

A large membrane-bound organelle in plant cells that maintains cellular turgor pressure and stores water and solutes.

Endosymbiosis Theory

The evolutionary theory proposing that eukaryotic organelles like mitochondria and chloroplasts originated as free-living prokaryotes engulfed by ancestral cells.

Extracellular Matrix

A network of glycoproteins such as collagen and elastin secreted outside animal cells that binds to integrins to provide structural support.

Tight Junctions

Cellular connections that seal the plasma membranes of adjacent animal cells together in a sheet, preventing leakage between cells.

Desmosomes

Adhesive junctions that mechanically attach the cytoskeletons of adjacent cells to each other via cadherin proteins.

Plasmodesmata

Specialized cytoplasmic channels passing through adjacent plant cell walls that allow direct intercellular transport and communication.