EST II Biology Comprehensive Lecture Review

Comprehensive practice vocabulary flashcards covering the core principles, cellular structures, physiological processes, genetic rules, and ecological concepts presented in Dr. David Girgius's EST II Biology lecture notes.

Cell Theory

A fundamental biological theory stating that all living things are composed of cells (with the exception of viruses), cells are the basic structural and functional unit of all organisms, and all cells arise from preexisting cells.

Theory of Endosymbiosis

The evolutionary proposal that eukaryotic organelles such as mitochondria and chloroplasts originated when free-living prokaryotes took up permanent residence inside larger ancestral prokaryotic cells, supported by both organelles possessing circular DNA and replicating independently.

Nucleolus

A prominent non-membrane bound region inside the nucleus of a non-dividing cell, composed of tangles of chromatin and unfinished ribosome precursors, that functions in the synthesis and assembly of ribosomes.

Smooth Endoplasmic Reticulum (SER)

A cytoplasmic network of membrane channels devoid of ribosomes that functions in synthesizing lipids and steroid hormones, metabolizing carbohydrates, detoxifying cell toxins, and connecting the rough ER to the Golgi apparatus.

Lysosome

A single membrane-bound sac containing hydrolytic digestive enzymes found only in animal cells; it carries out intracellular digestion, recycles worn-out organelles, and mediates apoptosis (programmed cell death).

Contractile Vacuole

A specialized organelle found in freshwater protists like amoeba and paramecium that collects and actively pumps excess water out of the cell against osmotic influx.

Fluid Mosaic Model

A model describing the plasma membrane structure as a flexible phospholipid bilayer embedded with proteins, cholesterol molecules that regulate fluidity and stability, and external carbohydrate recognition chains.

Pinocytosis

A form of endocytosis ('cell drinking') where the plasma membrane invaginates to take up droplets of extracellular fluid containing dissolved molecules into small vesicles.

Specific Heat Capacity (Water)

The property defining the high amount of heat energy required to raise the temperature of $1\,\text{g}$ of water by $1\,^\circ\text{C}$, providing thermal stability for aquatic environments and aiding homeostatic temperature regulation in organisms.

Cohesion (Water)

The intermolecular attraction between like water molecules via hydrogen bonds, which facilitates the continuous ascent of sap within plant xylem vessels against gravity.

Isomer

Molecules that share the identical chemical and molecular formula (such as glucose, fructose, and galactose, $\text{C}_6\text{H}_{12}\text{O}_6$) but possess different structural arrangements and physical-chemical properties.

Dehydration Synthesis

A condensation reaction in which monomers are covalently bonded together to synthesize polymers, accompanied by the simultaneous loss and production of a water ($\text{H}_2\text{O}$) molecule.

Activation Energy ($\text{E}_\text{A}$)

The initial amount of energy needed to destabilize chemical bonds in reactant molecules to start a reaction, which enzymes lower to accelerate reaction rates.

Law of Segregation

Mendel's first law stating that during gamete formation, the two alleles of a gene pair separate from one another so that each gamete receives only one allele for that trait.

Law of Independent Assortment

Mendel's second law stating that the alleles of two or more independent gene pairs segregate into gametes completely independently of each other, yielding a phenotypic ratio of $9:3:3:1$ in a dihybrid cross.

Incomplete Dominance

A non-Mendelian inheritance pattern where neither allele is fully dominant in the heterozygous state, resulting in a intermediate phenotype that appears as a blend of both parental alleles (e.g., Japanese four-o'clock flowers).

Codominance

A non-Mendelian pattern in which both alleles of a gene pair are fully and equally expressed in the heterozygote without blending (e.g., AB blood type and speckled chickens).

Linked Genes

Genes located close together on the same physical chromosome that tend to be inherited together and do not sort independently, unless separated during crossing over.

Karyotype

A standardized visual display of an individual's chromosomes arranged in homologous pairs according to size, shape, and number, prepared from cells arrested in mitotic metaphase.

Semiconservative Replication

The mechanism of DNA duplication in which the double helix unwinds and each parent strand serves as a template, producing two daughter duplexes that each consist of one original strand and one newly formed strand.

Telomeres

Repetitive, non-coding nucleotide sequences located at the ends of eukaryotic chromosomes that protect vital gene sequences from erosion during successive rounds of replication.

Introns

Non-coding segments of eukaryotic precursor messenger RNA that are transcribed from DNA but excised and discarded by enzymes prior to translation, allowing exons to be spliced together.

Operon

A coordinated cluster of bacterial genes with related metabolic functions, regulated as a single unit consisting of a promoter, an operator, and structural genes (e.g., the lac operon of Escherichia coli).

Restriction Enzymes

Bacterial endonuclease enzymes ('molecular scissors') that recognize and cut foreign double-stranded DNA at specific palindromic nucleotide sequences.

Polymerase Chain Reaction (PCR)

An automated, cell-free laboratory technique that exponentially amplifies targeted segments of DNA in vitro using repetitive cycles of denaturation, primer annealing, and extension by DNA polymerase.

Nondisjunction

An error during meiosis or mitosis in which homologous chromosome pairs or sister chromatids fail to separate properly, resulting in abnormal gametes with abnormal chromosome numbers (aneuploidy).

Photolysis

The light-driven enzymatic splitting of water molecules ($\text{H}_2\text{O} \rightarrow 2\text{H}^+ + \frac{1}{2}\text{O}_2 + 2e^-$) occurring in the grana during the light-dependent reactions of photosynthesis.

Calvin Cycle

The series of light-independent, cyclic enzymatic reactions in the stroma of chloroplasts that utilizes ATP and NADPH to reduce and fix carbon dioxide into carbohydrates (PGAL).

Glycolysis

The universal anaerobic metabolic pathway occurring in the cytosol that oxidizes one molecule of glucose ($6\text{C}$) into two molecules of pyruvic acid ($3\text{C}$), generating a net yield of $2\,\text{ATP}$ and $2\,\text{NADH}$.

Chemiosmosis

The synthesis of ATP coupled to the flow of protons ($\text{H}^+$) back across the inner mitochondrial membrane (or thylakoid membrane) through ATP synthase down an electrochemical gradient.

Synapsis

The precise physical pairing of homologous replicated chromosomes to form tetrads during prophase I of meiosis, enabling the reciprocal exchange of genetic material via crossing over.

Fixed Action Pattern (FAP)

An innate, stereotyped, and unlearned behavioral sequence triggered by an external sensory cue (sign stimulus) that proceeds inexorably to completion once initiated.

Habituation

A simple form of learned behavior characterized by a progressive decline in response to a persistent or repetitive sensory stimulus that carries neither benefit nor harm.

Imprinting

A form of learned behavior restricted to a specific sensitive or critical early developmental period that is rapid, innate-like, and generally irreversible.

Casparian Strip

A band of waterproof suberin embedded in the transverse and radial cell walls of root endodermal cells that blocks apoplastic movement, forcing water and solutes to cross the selectively permeable plasma membrane into the vascular cylinder.

Transpiration Pull

The negative pressure tension generated by the evaporative loss of water vapor from leaf stomata that pulls the continuous column of water upward through the xylem via cohesion and adhesion.

Phototropism

The directional growth of a plant organ in response to light, caused by the lateral redistribution of auxins toward the shaded side of the stem to promote asymmetric cell elongation.

Binomial Nomenclature

The formal Linnaean taxonomic system of naming organisms using a two-part scientific name consisting of the capitalized genus name followed by the lowercase species identifier.

Cephalization

The evolutionary specialization and concentration of sensory organs, nervous tissue, and mouthparts at the anterior end of a bilaterally symmetrical organism to form a distinct head region.

Coelom

A fluid-filled internal body cavity that is completely enclosed and lined on all sides by tissue derived from embryonic mesoderm.

Carrying Capacity

The maximum population size of a biological species that a specific environmental ecosystem can sustainably support indefinitely given the available limiting resources.

Biological Magnification

The progressive bioaccumulation and increase in concentration of persistent, fat-soluble toxins (such as the pesticide DDT) within organisms at successively higher trophic levels of a food web.

Homologous Structures

Anatomical features in different species that share an underlying structural and developmental plan derived from a common ancestor, regardless of whether their current functions differ.

Adaptive Radiation

The rapid evolutionary diversification of a single ancestral lineage into a multitude of new species specialized to exploit distinct ecological niches and resources (e.g., Darwin's Galapagos finches).

Genetic Drift

Random, non-selective fluctuations in the allele frequencies of a gene pool from one generation to the next due to chance events, exerting its strongest effect in small populations.

Peristalsis

The involuntary, coordinated wave-like contractions and relaxations of smooth muscle layers in the walls of the gastrointestinal tract that propel food through the alimentary canal.

Nephron

The microscopic structural and functional filtering unit of the mammalian kidney, comprising a glomerulus, Bowman's capsule, convoluted tubules, the Loop of Henle, and a collecting duct.

Sinoatrial (SA) Node

The intrinsic pacemaker of the heart, consisting of specialized myogenic muscle tissue located in the right atrium that spontaneously initiates the electrical impulses driving rhythmic heartbeats.

Sarcomere

The basic repeating contractile unit of a muscle myofibril, defined as the region between two adjacent Z-lines, consisting of overlapping thick (myosin) and thin (actin) protein filaments.

Gastrulation

The morphogenetic developmental process following blastula formation in which embryonic cells migrate and rearrange to establish the three primary embryonic germ layers: ectoderm, mesoderm, and endoderm.