Inquiry into Life: Chapters 1, 2, and 3 Study Flashcards

Comprehensive vocabulary flashcards covering the characteristics of life, chemistry, macromolecules, and cell structures across Chapters 1, 2, and 3.

Levels of Biological Organization

The structural hierarchy of life extending from atoms to molecules, cells, tissues, organs, organ systems, organisms, species, populations, communities, ecosystems, and the biosphere.

Homeostasis

The maintenance of a relatively constant and stable internal environment within an organism or cell despite external changes.

Metabolism

The sum of all chemical reactions that occur within a cell or organism.

Adaptation

Modifications or features that make organisms better suited to survive and reproduce in a changing environment.

Natural Selection

The differential reproductive success of adapted individuals, which causes the characteristics of a population to change over time and drives evolution.

Taxonomy

The scientific discipline of identifying, naming, and classifying organisms based on their shared traits.

Systematics

The study of evolutionary relationships among organisms used to classify them appropriately into taxa.

Domain Archaea

The domain of single-celled prokaryotic organisms that lack a nucleus, lack peptidoglycan in their cell walls, and often live in extreme environments mimicking primitive Earth.

Domain Bacteria

The domain of single-celled prokaryotic organisms that lack a membrane-bound nucleus, possess cell walls containing peptidoglycan, and inhabit nearly every environment on Earth.

Domain Eukarya

The domain comprising both single-celled and multicellular organisms whose cells contain membrane-bound organelles and a true nucleus.

Hypothesis

A tentative, testable, and falsifiable statement that provides a possible explanation for a natural event or observation.

Standard Error

A statistical parameter depicted on data graphs to quantify uncertainty and variation surrounding calculated mean values.

Experimental Variable

The single factor in an experiment that is deliberately manipulated or tested; also known as the independent variable.

Responding Variable

The measurable result or change that occurs due to the manipulation of the experimental variable; also known as the dependent variable.

Double-Blind Study

A controlled clinical research design where neither the participating patients nor the examining doctors know who receives the active medication or the placebo.

Scientific Theory

A widely accepted, overarching concept that unites numerous well-tested and supported hypotheses through extensive observations, experiments, and data.

Atomic Structure

The composition of an atom consisting of a dense central nucleus with protons and neutrons surrounded by orbiting electrons within shells.

Isotopes

Atoms of the same chemical element that possess the identical atomic number (number of protons) but differ in neutron number and atomic mass.

Radioisotopes

Unstable isotopes that decay and emit detectable energy called radiation, used in low doses for medical imaging or sterilizing equipment and in high doses to target cancer cells.

Ionic Bond

A chemical bond established by the electrostatic attraction between positively charged ions (electron donors) and negatively charged ions (electron acceptors).

Covalent Bond

A strong chemical bond formed when two atoms share one or more pairs of electrons to complete their valence shells.

Polar Covalent Bond

A covalent bond where electrons are shared unequally between atoms because one atom exerts a stronger pull on electrons than the other.

Hydrogen Bond

A relatively weak polar attraction occurring between a slightly positive hydrogen atom in one molecule and a slightly negative atom (such as oxygen) in an adjacent molecule.

Cohesion

The tendency of water molecules to cling together through hydrogen bonding, giving water high surface tension and a high boiling point.

Adhesion

The ability of water molecules to cling to external polar surfaces, such as the inner walls of blood vessels.

Calorie

The measurement of heat energy needed to elevate the temperature of $1\,\text{g}$ of water by $1^\circ\text{C}$.

pH Scale

A logarithmic measurement scale extending from $0$ to $14$ indicating the relative concentration of hydrogen ions ($\text{H}^+$) in a solution.

Buffer

A chemical compound or system that maintains solutions within a narrow pH range by binding excess $\text{H}^+$ or $\text{OH}^-$ ions.

Dehydration Reaction

A synthetic chemical reaction that links smaller monomer subunits into polymers through the removal of a water molecule ($-\text{OH}$ from one subunit and $-\text{H}$ from another).

Hydrolysis Reaction

A decomposition chemical process that breaks down macromolecules into smaller subunits through the chemical addition of a water molecule.

Monosaccharide

A simple single-ring carbohydrate monomer having a carbon, hydrogen, and oxygen ratio of $1:2:1$, such as glucose ($\text{C}_6\text{H}_{12}\text{O}_6$), fructose, or galactose.

Glycogen

A highly branched polysaccharide that functions as the primary storage form of glucose in animal liver and muscle tissue.

Starch

A branched or unbranched storage polysaccharide made of glucose monomers synthesized by plants.

Cellulose

A structural polysaccharide found in plant cell walls composed of parallel glucose chains, commonly recognized as dietary fiber.

Triglyceride

A neutral lipid molecule composed of one glycerol molecule linked to three fatty acid chains, serving in long-term energy storage, insulation, and cushioning.

Saturated Fatty Acid

A fatty acid chain that has no double covalent bonds between its carbon atoms, containing the maximum amount of bonded hydrogen atoms and remaining solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain possessing one or more double covalent bonds ($\text{C}=\text{C}$), resulting in bends that maintain a liquid state at room temperature.

Phospholipid

A membrane-forming lipid featuring a polar, hydrophilic phosphate head and two nonpolar, hydrophobic fatty acid tails.

Steroids

Lipids characterized by a rigid backbone of four fused carbon rings, serving as membrane components (such as cholesterol) or precursor hormones (like estrogen and testosterone).

Peptide Bond

The covalent linkage formed between the amino group of one amino acid and the carboxyl acid group of another via dehydration synthesis.

Protein Denaturation

The disruption and loss of a protein's functional three-dimensional shape triggered by extreme temperature or severe pH changes.

Nucleotide

The structural monomer of nucleic acids, consisting of a phosphate group, a five-carbon sugar (ribose or deoxyribose), and a nitrogen-containing base.

Adenosine Triphosphate

A high-energy nucleotide containing adenosine linked to three phosphate groups that functions as the primary energy carrier for cellular work.

Cell Theory

A unifying biological principle stating that all living things are composed of cells, the cell is the basic structural and functional unit of life, and all cells arise only from preexisting cells.

Surface-Area-to-Volume Ratio

A mathematical relationship dictating that as a cell expands in size, its volume increases much faster than its surface area, limiting cell size for efficient nutrient and waste exchange.

Light Microscope vs. Electron Microscope

Microscopy modalities where light microscopes utilize glass lenses to magnify specimens up to $1{,}500\times$ ($250\,\text{nm}$ resolution), whereas electron microscopes utilize magnetic lenses and electron beams to magnify specimens up to $1{,}000{,}000\times$ ($< 1\,\text{nm}$ resolution).

Prokaryotic Cell Anatomy

The cellular arrangement of a bacterium comprising a cell envelope (capsule, cell wall, and plasma membrane), cytoplasm housing ribosomes and a membrane-less nucleoid, and exterior appendages including flagella and fimbriae.

Peptidoglycan

A complex, rigid polymer composed of disaccharides and amino acids that forms the cell wall of most bacteria.

Glycocalyx

A polysaccharide layer lying outside the bacterial cell wall that prevents dehydration, assists in surface adhesion, and acts as a protective capsule against host immune attacks.

Nucleoid

The non-membrane-enclosed region of a prokaryotic cell where the single circular bacterial chromosome is situated.

Plasmid

A small, circular, extrachromosomal loop of DNA found in many prokaryotes that can replicate independently.

Conjugation Pili

Rigid, tubular protein structures utilized by prokaryotes to transfer DNA directly between cells.

Nucleolus

A dense, dark region located inside the eukaryotic nucleus responsible for the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomal subunits.

Nuclear Envelope

A double membrane perforated by nuclear pores that surrounds the nucleus, studded with ribosomes and continuous with the rough endoplasmic reticulum.

Rough Endoplasmic Reticulum

A network of folded internal membranes studded with ribosomes, responsible for processing, folding, and packaging newly synthesized proteins into transport vesicles.

Smooth Endoplasmic Reticulum

A continuous network of folded internal membranes lacking ribosomes that synthesizes phospholipids, produces various lipids, and metabolizes and detoxifies chemicals.

Golgi Apparatus

A stack of $3$ to $20$ curved, flattened sacs (cisternae) featuring a receiving cis face and a shipping trans face that modifies, sorts, and packages ER-derived lipids and proteins.

Lysosome

A Golgi-derived membrane-bound vesicle filled with digestive enzymes that breaks down foreign bacteria, cellular debris, and damaged organelles.

Peroxisome

A specialized membrane-bound vesicle containing oxidative enzymes that break down fatty acids, producing hydrogen peroxide ($\text{H}_2\text{O}_2$) which is converted into water and oxygen by catalase.

Central Vacuole

A large fluid-filled organelle characteristic of plant cells that stores water, nutrients, pigments, and toxins while providing structural support via turgor pressure.

Chloroplast

A photosynthetic double-membrane plant organelle containing fluid stroma and stacks of flattened thylakoid membranes (grana) containing chlorophyll.

Mitochondrion

The double-membrane eukaryotic organelle responsible for cellular respiration, possessing inner folds called cristae and an internal fluid-filled matrix to generate ATP.

Actin Filaments

Long, thin, flexible cytoskeletal filaments consisting of two twisted actin chains that form a structural web beneath the plasma membrane, construct microvilli, and enable pseudopod movement.

Intermediate Filaments

Tough, ropelike cytoskeletal fibers intermediate in diameter that reinforce cell-to-cell junctions, stabilize the nuclear envelope, and provide structural strength to hair.

Microtubules

Hollow cylinders composed of assembled alpha and beta tubulin dimers that serve as internal tracks for motor proteins, build the mitotic spindle, and construct cilia and flagella.

Centriole ($9 + 0$ Pattern)

A short, barrel-shaped animal organelle found within the centrosome composed of nine microtubule triplets surrounding a hollow center, functioning in spindle fiber formation during cell division.

$9 + 2$ Pattern vs. $9 + 0$ Pattern

The structural configurations of microtubules seen in cross-section: the $9 + 2$ pattern contains nine outer doublets surrounding two central single microtubules in motile cilia and flagella, whereas the $9 + 0$ pattern contains nine triplets surrounding an empty center in centrioles and basal bodies.

Endosymbiotic Theory

The evolutionary theory stating that eukaryotic mitochondria and chloroplasts originated as free-living heterotrophic bacteria and cyanobacteria engulfed by larger ancestral prokaryotic cells.