General Biology 1 Comprehensive Study Guide

A comprehensive set of vocabulary flashcards covering the General Biology 1 curriculum, including cell theory, organelle function, cell division, transport, and biomolecules.

Cell Theory Principle 1

Every living organism consists of one or more cells, which can be unicellular like bacteria or multicellular like plants.

Cell Theory Principle 2

The cell is the fundamental structural and functional unit of life and is the smallest unit displaying all characteristics of living things.

Cell Theory Principle 3

Cells arise only from pre-existing cells through cell division, a postulate that disproved the theory of Spontaneous Generation.

Zacharias Janssen

Individual who invented the first primitive compound microscope in the late 16th to early 17th century.

Robert Hooke

Scientist who observed cork slices and coined the term "cell" ($cellulae$) after monastery rooms.

Francesco Redi

Scientist who disproved the spontaneous generation of maggots using controlled meat jars.

Anton van Leeuwenhoek

The first to observe living microorganisms, which he called "animalcules," using handcrafted high-power lenses.

Matthias Schleiden

Proposed in 1838 that all plants are composed of cells and cell products.

Theodor Schwann

Proposed in 1839 that all animals are composed of cells and synthesized the first two cell theory principles.

Rudolf Virchow

Formulated the aphorism "$Omnis cellula e cellula$" in 1855, stating all cells arise from pre-existing cells.

Surface Area-to-Volume Ratio ($SA:Vol$)

The constraint where volume expands faster ($r^3$) than surface area ($r^2$) as a cell grows; smaller cells maintain a higher ratio for efficient nutrient and waste exchange.

Homeostasis

The regulation of a cell's internal environment to maintain a stable, constant state, such as perspiration or shivering.

Fluid Mosaic Model

Descriptive model of the plasma membrane as a dynamic matrix consisting of phospholipids, proteins, cholesterol, and carbohydrates.

Phospholipid Bilayer

A double layer of amphipathic molecules with hydrophilic phosphate heads facing outward and hydrophobic fatty acid tails sandwiched inside.

Channel Proteins

Membrane proteins that provide hydrophilic passages for the movement of small ions or water.

Carrier Proteins

Membrane proteins that undergo conformational shape changes to transport specific substances across the membrane.

Microfilaments (Actin)

The thinnest cytoskeletal fibers ($7\,nm$) involved in cell motility, muscle contraction, and cleavage furrow formation.

Intermediate Filaments

Cytoskeletal fibers ($8\text{--}12\,nm$) composed of proteins like Keratin that provide structural integrity and anchor the nucleus.

Microtubules

The thickest cytoskeletal fibers ($25\,nm$) made of $\alpha$- and $\beta$-Tubulin dimers; they guide organelle movement and form mitotic spindles, cilia, and flagella.

Cell Wall Diversity

Structural layers made of cellulose in plants, chitin in fungi, and peptidoglycan ($murein$) in bacteria.

Nucleolus

A dense region inside the nucleus responsible for ribosomal RNA ($rRNA$) synthesis and ribosome assembly.

Ribosomes

Non-membrane-bound complexes of $rRNA$ and proteins; 70S type is found in prokaryotes/organelles, and 80S type is found in eukaryotes.

Rough Endoplasmic Reticulum (RER)

A system of membranes studded with ribosomes that synthesizes and modifies secretory proteins.

Smooth Endoplasmic Reticulum (SER)

A membrane system that synthesizes lipids, metabolizes carbohydrates, detoxifies poisons, and stores calcium ions.

Golgi Apparatus

The cell's warehouse consisting of flattened sacs ($cisternae$) that modifies, sorts, and dispatches proteins via vesicles.

Lysosomes

Membranous sacs containing acid hydrolases for intracellular digestion, phagocytosis, and autophagy.

Peroxisomes

Metabolic microbodies that oxidize fatty acids, producing $H_2O_2$ which is then broken down by catalase into $2H_2O + O_2$.

Endosymbiotic Theory

Proposed by Lynn Margulis, it states that mitochondria and chloroplasts originated as free-living prokaryotes engulfed by an ancestral eukaryote.

Nucleoid Region

The open region in prokaryotic cells where genetic material is located, lacking a membrane-bound nucleus.

Plasmids

Small, circular DNA molecules found in prokaryotes independent of the main genomic DNA.

Microvilli

Non-motile finger-like apical modifications that increase surface area for nutrient absorption in the small intestine.

Cilia

Motile hair-like structures with a $9+2$ microtubule core that move mucus and debris in the respiratory tract.

Tight Junctions ($Zonula\ occludens$)

Junctions that seal adjacent cell membranes to prevent fluid leakage between cells.

Gap Junctions

Protein channels called connexons that allow direct intercellular passage of ions, water, and signaling molecules.

Erythrocytes (Red Blood Cells)

Biconcave cells that lack a nucleus and mitochondria when mature to maximize room for hemoglobin and gas diffusion.

Xylem

Non-living vascular tissue consisting of tracheids and vessel elements that conduct water upward from roots.

Phloem

Living vascular tissue composed of sieve-tube elements and companion cells that transport organic sugars throughout the plant.

Chromatin

An uncoiled thread-like network of DNA wrapped around histone proteins found during interphase.

Ploidy

The number of chromosome sets; Diploids ($2n=46$ in humans) have two sets, while Haploids ($n=23$ in humans) have one set.

S Phase (Synthesis)

The sub-phase of interphase where DNA replication occurs, resulting in chromosomes with two identical sister chromatids.

G0 Phase

A non-dividing state entered by cells if they fail the $G_1/S$ (Restriction Point) checkpoint.

Metaphase Checkpoint

The quality control step ensuring all kinetochores are correctly attached to spindle fibers before initiating anaphase.

Mitosis

Somatic cell division producing two genetically identical diploid ($2n$) daughter cells for growth and repair.

Crossing Over

The exchange of genetic segments between non-sister chromatids at chiasmata during Prophase I of meiosis.

Meiosis I

The reductional division phase that separates homologous chromosome pairs, resulting in two haploid cells.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during division, leading to aneuploidy.

Trisomy 21

Commonly known as Down Syndrome, it is an aneuploidy characterized by having three copies of chromosome 21 ($47, XX/XY, +21$).

Turner Syndrome

A monosomy condition in females characterized by a single X chromosome ($45, X0$), resulting in short stature and sterility.

Metastasis

The process where malignant cancer cells spread through blood or lymphatic channels to colonize distant organs.

Simple Diffusion

The passive movement of small, nonpolar molecules like $O_2$ and $CO_2$ down their concentration gradient.

Osmosis

The diffusion of water across a selectively permeable membrane from higher water concentration to lower water concentration.

Hypertonic Solution

A solution with a higher solute concentration than the cell, causing animal cells to shrivel (crenate) and plant cells to plasmolyze.

Sodium-Potassium Pump ($Na^+/K^+$ ATPase)

An active transport pump that moves $3\,Na^+$ OUT and $2\,K^+$ IN per ATP to maintain resting membrane potential.

Phagocytosis

A form of endocytosis known as "cell eating" where large solid particles or bacteria are engulfed using pseudopodia.

Receptor-Mediated Endocytosis

A specific intake mechanism where ligands bind to surface receptors, forming clathrin-coated vesicles (e.g., cholesterol uptake).

Apoenzyme

The inactive protein portion of an enzyme that requires a cofactor to become active.

Holoenzyme

The complete, active enzyme consisting of an apoenzyme plus its cofactor or coenzyme.

Denaturation

The unfolding of a protein's tertiary structure due to extreme temperature or pH, which destroys the active site.

Oxidation

The loss of electrons during a chemical reaction (Memory rule: OIL or LEO).

Reduction

The gain of electrons during a chemical reaction (Memory rule: RIG or GER).