Biology Chapters 1-4: Study of Life, Chemistry, Macromolecules, and Cell Structure

Vocabulary practice flashcards generated from Biology lecture notes covering Chapters 1 through 4.

Biology

The study of living organisms and the science of all living things.

Sir Francis Bacon

The English philosopher known as the Father of the scientific method.

Inductive Reasoning

A form of logical thinking that uses related observations to arrive at a general conclusion, moving from specific to general.

Deductive Reasoning

A form of logical thinking that uses a general principle or law to forecast specific results, moving from general to specific.

Independent Variable

The part of an experiment that is controlled or manipulated as the cause, typically plotted on the $x$-axis.

Dependent Variable

The part of an experiment that is measured to test the effect, typically plotted on the $y$-axis.

Chemotaxis

The movement of bacteria or cells toward or away from chemical stimuli.

Phototaxis

The movement of organisms toward or away from light stimuli.

Homeostasis

The ability of an organism to maintain steady internal conditions and set points despite environmental changes.

Carl Linnaeus

The Father of taxonomy who first proposed organizing known species of organisms into a hierarchy.

Carl Woese

The scientist who in the early 1970s showed that life on Earth evolved along three distinct domains: Bacteria, Archaea, and Eukarya.

Phylogenetic Tree

A diagram showing the evolutionary relationships among biological species based on similarities and differences in genetic or physical traits.

Forensic Science

The application of science to answer legal questions, involving the examination of trace materials such as hair, blood, and body fluids.

Atomic Number

The total number of protons present in the nucleus of an atom, unique to each element.

Atomic Mass

The total mass of an atom expressed in atomic mass units ($\text{amu}$), roughly equal to the combined number of protons and neutrons.

Isotopes

Variants of an element that have the exact same number of protons but differ in their number of neutrons.

Cation

A positively charged ion formed when an atom loses electrons, resulting in more protons than electrons.

Anion

A negatively charged ion formed when an atom gains electrons, resulting in fewer protons than electrons.

Octet Rule

The principle that an atom achieves its most stable configuration when its valence electron shell contains eight electrons.

Oxidation

The loss of one or more electrons by an atom or molecule during a chemical reaction, resulting in an overall more positive charge.

Reduction

The gain of one or more electrons by an atom or molecule during a chemical reaction, resulting in an overall more negative charge.

Non-polar Covalent Bond

A chemical bond formed when electrons are shared equally between atoms, such as in methane ($\text{CH}_4$).

Polar Covalent Bond

A chemical bond formed when electrons are unequally shared between atoms due to differences in electronegativity.

Van der Waals Interaction

Weak physical attractions between molecules in close proximity due to transient fluctuations in electron density.

Specific Heat Capacity

The amount of heat energy required to raise the temperature of one gram of a substance by $1^\circ\text{C}$.

Heat of Vaporization

The amount of energy required to convert one gram of a liquid substance into a gas.

Cohesion

The intermolecular attraction between like water molecules caused by hydrogen bonding, giving rise to surface tension.

Adhesion

The attraction between water molecules and other polar or charged molecules, enabling capillary action.

pH Scale

A measure of acidity or alkalinity defined as the negative base-10 logarithm of the hydrogen ion concentration, $\text{pH} = -\log_{10}[\text{H}^+]$.

Buffers

Chemical substances that maintain the internal pH of an organism near neutral by absorbing or releasing $\text{H}^+$ or $\text{OH}^-$ ions.

Structural Isomers

Molecules that share the same chemical formula but differ in the covalent arrangement of their constituent atoms.

Geometric Isomers

Molecules with identical covalent bonds that differ in the spatial placement of atoms around a double bond (cis vs. trans).

Enantiomers

Molecules that share the same chemical formula and bonds but differ in 3D placement of atoms, existing as non-superimposable mirror images.

Dehydration Synthesis

A chemical reaction that joins monomer subunits into polymers with the release of a water molecule ($\text{H}_2\text{O}$).

Hydrolysis

A reaction that breaks down polymers into smaller monomers through the chemical addition of a water molecule.

Glycogen

A branched storage polysaccharide used by animals to store energy in liver and muscle cells.

Cellulose

An unbranched polysaccharide made of $\beta\,1\text{-}4$ glycosidic linkages that forms the rigid cell walls of plants.

Chitin

A nitrogen-containing polysaccharide that forms the hard exoskeleton of arthropods and cell walls of fungi.

Saturated Fatty Acid

A hydrocarbon chain containing no double bonds between carbon atoms, saturated with hydrogen and solid at room temperature.

Unsaturated Fatty Acid

A hydrocarbon chain containing one or more double bonds that cause kinks in the chain, making it liquid at room temperature.

Phospholipid

An amphipathic lipid with two hydrophobic fatty acid tails and a hydrophilic phosphate head attached to a glycerol backbone.

Denaturation

Changes in protein structure caused by alterations in pH, temperature, or chemical exposure that lead to a loss of biological function.

Nucleotide

The monomer subunit of nucleic acids, consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Purines

A class of two-ring nitrogenous bases comprising Adenine and Guanine.

Pyrimidines

A class of single-ring nitrogenous bases comprising Cytosine, Thymine, and Uracil.

Resolving Power

The ability of a microscope or optical system to distinguish two adjacent structures as separate entities.

Unified Cell Theory

The biological principle stating that all living organisms are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells.

Prokaryotic Cell

A simple, mostly single-celled organism that lacks a membrane-bound nucleus and membrane-bound organelles.

Nucleolus

A dense region inside the eukaryotic nucleus where ribosomes are assembled from RNA and proteins.

DNA Packaging Hierarchy

The structural pathway showing how nucleosomes (composed of DNA and protein) form chromatin and replicate to form structured chromosomes.

Endosymbiotic Theory

The evolutionary theory proposed by Lynn Margulis stating that mitochondria and chloroplasts originated as independent prokaryotic organisms.

Lysosomes

Membrane-bound organelles in animal cells containing digestive enzymes that break down macromolecules, cellular waste, and worn-out organelles.

Golgi Apparatus

An organelle composed of flattened membranous sacs that sorts, modifies, packages, and tags lipids and proteins for transport.

Plasmodesmata

Channels passing through plant cell walls that connect adjacent cytoplasms to allow materials to move from cell to cell.

Desmosomes

Short protein junctions (cadherins) in animal tissues that act as spot welds joining cells in stretchable tissues like skin, heart, and lungs.

Tight Junctions

Watertight seals between adjacent animal cells that prevent fluids and materials from leaking between cells.

Gap Junctions

Intercellular channels formed by six connexin proteins (forming a connexon) in animal cells that allow direct transfer of ions and nutrients between cells.