General Biology: Molecular Genetics, Biotechnology, Evolution, and Biodiversity

Comprehensive vocabulary flashcards covering molecular genetics, transcription, translation, biotechnology, mechanisms of evolution, speciation, biodiversity, prokaryotes, protists, fungi, and animal phyla.

Double Helix

The structural shape of a DNA molecule, consisting of two strands wound around each other like a spiral staircase with complementary base pairs facing inward.

Base Pairing Rules

The strict biochemical rule governing DNA structure stating that adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).

DNA Replication

The biological process in which a double-stranded DNA molecule unwinds, separates, and synthesizes two identical daughter strands using enzymes and base-pairing rules.

Transcription

The process occurring inside the cell nucleus where the nucleotide sequence of a DNA template strand is copied into a complementary RNA sequence.

Messenger RNA (mRNA)

A single-stranded RNA molecule that carries the transcribed genetic instructions from DNA in the nucleus to ribosomes in the cytoplasm.

Translation

The cellular process occurring on ribosomes in the cytoplasm where the codon sequence of mRNA directs the assembly of amino acids into a polypeptide chain.

Codon

A specific sequence of three consecutive mRNA nucleotides that specifies a single amino acid or signals a start or stop during protein synthesis.

Transfer RNA (tRNA)

An RNA molecule that acts as a molecular decoder by pairing its specific anticodon with a complementary mRNA codon to deliver the correct amino acid to a ribosome.

Genetic Code Wheel

A circular reference chart used to identify amino acids from mRNA codons by reading bases sequentially from the central $5'$ base outward to the perimeter $3'$ base.

Gene Expression Pathway

The two-step flow of genetic information from DNA to RNA via transcription, and from RNA to protein via translation using start and stop codons.

Mutation

A random change in the nucleotide sequence of DNA that can result from replication errors, UV radiation, or chemical mutagens.

Sickle-Cell Hemoglobin Mutation

A specific point mutation where a single DNA base change from CTT to CAT (mRNA GAA to GUA) replaces glutamic acid (Glu) with valine (Val) in the hemoglobin protein.

Biotechnology

The deliberate manipulation of living organisms or biological systems to produce goods, foods, or pharmaceuticals.

Selective Breeding

An ancient form of biotechnology in which humans systematically breed individuals with desirable traits over generations, such as developing modern large-eared corn from ancestral teosinte.

Genetically Modified Organism (GMO)

An organism whose genome has been deliberately altered using genetic engineering techniques, typically by introducing a foreign gene into an egg cell.

CRISPR

A targeted gene-editing technology developed in 2012 that uses engineered molecules to directly alter DNA sequences within living cells and organisms.

Bt Gene

A gene derived from soil bacteria and inserted into crops to produce a protein toxic to pest insects, conferring natural insect resistance.

Glyphosate

The most widely used chemical herbicide applied to genetically modified, herbicide-tolerant agricultural crops.

Reproductive Cloning

The laboratory procedure of using a somatic cell nucleus from an organism to generate a genetically identical individual, first achieved in a mammal with Dolly the sheep in 1996.

mRNA Vaccine

A vaccine type, such as the Pfizer and Moderna COVID-19 vaccines, that delivers genetic instructions for host cells to produce a viral protein and train the immune system without altering host DNA.

Gene Therapy

A clinical strategy that treats or prevents genetic diseases by introducing functional alleles via viral vectors, or by editing and replacing defective alleles.

DNA Profiling

A forensic laboratory method that analyzes unique patterns and variations in an individual's DNA for crime investigation, paternity testing, and genealogy.

Evolution

The biological process through which the heritable characteristics of populations change over successive generations, leading to the emergence of new species.

Alleles

Alternative molecular versions or sequence variants of a specific gene that produce variations in inherited traits.

Natural Selection

An evolutionary mechanism in which individuals possessing traits favored by environmental pressures survive and reproduce at higher rates, increasing those alleles in the population.

Biological Fitness

A quantitative measure of an individual's reproductive success, determined by the relative number of viable offspring it contributes to the next generation.

Genetic Drift

A non-directional mechanism of evolution involving random fluctuations and losses of alleles across generations, which most severely reduces diversity in small populations.

Gene Flow

The transfer of alleles between separate populations caused by the migration and interbreeding of fertile individuals.

Transitional Fossils

Fossilized remains that demonstrate intermediary body structures between ancestral forms and modern descendants, such as the gradual reduction of pelvic and leg bones in the whale lineage from Pakicetus to Dorudon.

Homologous Structures

Anatomical features in different species that share an underlying skeletal design inherited from a common ancestor, such as the humerus, radius, ulna, carpals, metacarpals, and phalanges in human, cat, whale, and bat forelimbs.

Vestigial Structures

Underdeveloped or remnant anatomical structures that performed critical functions in ancestors but have lost their original utility in modern organisms, such as the pelvic bones in living whales.

Biological Species Concept

A species definition that groups organisms based on their ability to interbreed in nature and produce viable, fertile offspring.

Intraspecific Variation

Differences in morphological appearance, color patterning, or physical traits among individuals belonging to the exact same interbreeding species.

Behavioral Isolation

A prezygotic reproductive barrier occurring when two closely related populations develop differing courtship songs, rituals, or displays that prevent cross-mating, as seen in Eastern and Western meadowlarks.

Temporal Isolation

A prezygotic barrier in which related species cannot mate because their active breeding periods occur during different seasons, times of year, or times of day.

Speciation

The evolutionary lineage-splitting event where a single ancestral population becomes reproductively isolated and diverges genetically into two or more distinct species.

Localized Distribution

An ecological state in which a species is naturally confined to a tiny geographic range, increasing its susceptibility to extinction.

Invasive Species

Non-native organisms introduced into an ecosystem that cause ecological harm to native species through predation, intense competition, or disease transmission.

Prokaryotes

Single-celled microscopic organisms belonging to domains Archaea and Bacteria that lack a membrane-enclosed nucleus and internal organelles.

Prochlorococcus

A marine photosynthesizing bacterium discovered in 1988 with an estimated $3\text{ billion}$ cells per liter in open ocean water, responsible for generating approximately $\frac{1}{5}$ of Earth's oxygen.

Human Microbiome

The complex community of microscopic organisms, including both bacteria and archaea, living symbiotically inside and on the human body, typically weighing $2\text{ to }5\,\text{lbs}$.

Protists

An informal classification grouping all eukaryotic organisms within Domain Eukarya that are not categorized as plants, animals, or fungi.

Dinoflagellates

Unicellular marine algae that can produce toxic algal blooms known as red tides, exhibit bioluminescence at night, or live as endosymbionts called zooxanthellae.

Fungi

Heterotrophic eukaryotes belonging to Domain Eukarya that acquire nourishment by secreting digestive enzymes externally and absorbing the dissolved nutrients.

Hyphae

The network of microscopic, branching, threadlike filaments that forms the structural feeding body of a multicellular fungus.

Animal

A multicellular, heterotrophic eukaryote belonging to Domain Eukarya that acquires nutrients and energy through ingestion.

Phylum

A primary taxonomic rank in biological classification situated directly beneath kingdom and directly above class.

Sponges

The oldest and simplest group of multicellular animals, originating over half a billion years ago, characterized by an absence of true tissues, nerves, and organs.

Phylum Cnidaria

An animal phylum displaying radial symmetry, true tissues, and decentralized nerve nets without a brain, comprising jellies, sea anemones, hydras, and corals.

Phylum Platyhelminthes

The invertebrate flatworm phylum possessing bilateral symmetry, a simple brain, and a single-opening gastrovascular cavity where the mouth functions as an anus.

Phylum Arthropoda

The most diverse animal phylum, defined by jointed legs and a rigid, non-living chitinous exoskeleton that must be periodically shed through molting.

Insects

A class of six-legged arthropods representing approximately $80\%$ of all recognized animal species, distinguished as the only invertebrates capable of powered flight.

Phylum Mollusca

A soft-bodied animal phylum featuring a characteristic muscular foot and typically an external calcium shell, comprising snails, bivalves, and cephalopods.

Phylum Chordata

The animal phylum that encompasses all vertebrate organisms possessing an internal backbone, including fish, amphibians, reptiles, birds, and mammals.

Lobe-Finned Fish

A lineage of bony fishes possessing fleshy, muscular fins supported by robust internal bones homologous to the limbs of terrestrial vertebrates.

Tetrapods

A evolutionary group of four-limbed vertebrate animals that transitioned from shallow aquatic environments onto dry land, comprising amphibians and amniotes.

Amniotes

A lineage of tetrapods, including reptiles, birds, and mammals, whose embryos develop inside a protective fluid-filled amnion, freeing reproduction from standing water.

Placental Mammals

The most widespread mammalian group, wherein offspring undergo long-term embryonic development inside the maternal uterus supported by a nourishing placenta.