General Biology 1: Chapters 1 to 5 Comprehensive Review

Comprehensive vocabulary flashcards covering the study of life, cell biology, microscopy, mitosis, meiosis, chromosome genetics, and membrane transport mechanisms.

Biology

The science that deals with the structures, functions, and relationships of living organisms with their environment, derived from the Greek words bios meaning "life" and logos meaning "study".

Spontaneous Generation

The historical idea proposed by Aristotle stating that living organisms can originate directly from lifeless matter.

Cell Theory

A unifying biological theory stating that all organisms are composed of one or more cells, the cell is the basic structural and functional unit of life, and all cells arise exclusively from preexisting cells.

Gene Theory

The core biological principle asserting that inherited genetic information dictates the specific structure, function, and behavior of living organisms.

Theory of Evolution by Natural Selection

The biological principle stating that organisms possess inherited traits that can make them adaptable to changing conditions within their environment.

Pasteur's Swan-Neck Flask Experiment

A classic experiment demonstrating that air carries microorganisms and that life comes from preexisting life, refuting spontaneous generation by preventing airborne contamination in an intact curved-neck flask.

Panspermia

The hypothesis proposing that life on Earth originated from extraterrestrial sources, supported by discoveries such as the detection of a complete set of canonical nucleobases on the carbonaceous asteroid (162173) Ryugu.

Micrograph

The visual photograph or digital image produced by a microscope.

Compound Microscope

An optical instrument equipped with multiple lenses designed to enlarge specimens up to several hundred times, reaching a maximum magnification of up to $2000\times$.

Stereomicroscope (Dissecting Microscope)

A low-power microscope equipped with binocular eyepieces used primarily to examine and dissect the three-dimensional, external structures of specimens such as insects.

Phase-Contrast Microscope

A specialized light microscope that exploits refractive index variations to observe highly transparent, unstained living specimens.

Transmission Electron Microscope (TEM)

A high-resolution electron microscope that transmits an electron beam through ultrathin sectioned specimens to study internal cellular ultrastructure.

Scanning Electron Microscope (SEM)

An electron microscope that scans the surface of a specimen with an electron beam to generate detailed three-dimensional images of surface contours and structures.

Cytosol

The fluid portion of the cytoplasm, consisting mainly of water and dissolved solutes, excluding the organelles suspended within it.

Plastids

Double-membraned organelles found in plants, algae, and some protists that perform essential biochemical functions such as photosynthesis, pigment storage, and lipid/amino acid biosynthesis.

Cytoskeleton

A dynamic intracellular protein network consisting of microfilaments, microtubules, and intermediate filaments that provides structural support, facilitates organelle movement, and maintains cell shape.

Plasmodesmata

Microscopic cytoplasmic channels traversing plant cell walls—containing a desmotubule and cytoplasmic sleeve—that facilitate direct transport and intercellular communication between plant cells.

Cell Division

A crucial biological process responsible for creating daughter cells from parent cells to support growth, development, cell replacement, and reproduction.

Mitosis

The division of a somatic eukaryotic cell's nucleus into two genetically identical daughter nuclei, each retaining the full set of parental chromosomes.

Sister Chromatids

Two identical, replicated copies of a chromosome produced during DNA synthesis, held together at the centromere by cohesin proteins.

Cell Cycle

The complete series of regulatory stages encompassing cell growth ($G_1$), DNA synthesis (S), preparation for division ($G_2$), and nuclear and cytoplasmic division (M phase and cytokinesis).

Cytokinesis

The physical cleavage of the cytoplasm resulting in two daughter cells, achieved via a contractile ring and cleavage furrow in animal cells and via Golgi vesicle-mediated cell plate formation in plant cells.

Contact Inhibition

An external cell-cycle control mechanism where normal animal cells cease dividing once they come into physical contact with neighboring cells.

Apoptosis

Genetically programmed and orderly cell death that eliminates redundant, damaged, or unneeded cells to maintain tissue homeostasis.

Homologous Chromosomes

A pair of maternal and paternal chromosomes sharing identical lengths, gene loci, and centromere locations, which are not exact copies of each other.

Crossing Over

The reciprocal exchange of genetic segments between non-sister chromatids of homologous chromosomes at physical contact points called chiasmata during Prophase I of meiosis.

Independent Assortment

The random orientation of maternal and paternal homologous chromosome pairs along the equatorial plate during Metaphase I, creating $2^{23} = 8{,}388{,}608$ unique possible chromosome combinations in humans.

Spermatogenesis

The male developmental process in the testes producing four functional, viable haploid spermatozoa through equal divisions of cytoplasm, occurring continuously from puberty onwards.

Oogenesis

The female gametogenic process in ovaries that begins before birth, pauses in Prophase I until puberty, and uses unequal cytoplasmic division to yield a single viable ovum and nonfunctional polar bodies.

Nondisjunction

An error during anaphase of cell division wherein homologous chromosomes or sister chromatids fail to separate properly, resulting in gametes with abnormal chromosome numbers ($n+1$ or $n-1$).

Down Syndrome

An autosomal condition caused by trisomy 21 (three copies of chromosome 21), occurring in approximately $1$ out of $800$ newborns, primarily resulting from nondisjunction during oogenesis.

Turner Syndrome

A female sex chromosome monosomy disorder ($45, \text{XO}$) characterized by short stature, broad chest, webbed neck, and underdeveloped, sterile ovaries.

Klinefelter Syndrome

A male sex chromosome aneuploidy ($47, \text{XXY}$) characterized by an extra X chromosome, underdeveloped testes and prostate, delayed puberty, long limbs, and breast enlargement.

Homeostasis

The maintenance of stable, balanced internal physiological conditions necessary for cellular survival and metabolic functioning.

Fluid Mosaic Model

The structural representation of plasma membranes consisting of a flexible phospholipid bilayer with embedded transport proteins, cholesterol for fluidity control, and surface carbohydrate markers.

Simple Diffusion

The unassisted passive movement of small nonpolar molecules (such as $O_2$ and $CO_2$) directly across the lipid bilayer down their concentration gradient until reaching dynamic equilibrium.

Osmosis

The passive transport of water across a selectively permeable membrane toward a region of higher solute concentration to establish an equilibrium in water potential.

Aquaporin

A specialized membrane channel protein discovered by Peter Agre that facilitates rapid transcellular water movement, reabsorbing $150\text{--}200\,dm^3$ of water daily in human kidneys.

Plasmolysis

The shrinking of a plant cell's protoplast and the pulling away of its plasma membrane from the rigid cell wall when placed in a hypertonic environment.

Sodium-Potassium Pump

An ATP-dependent transport protein that actively moves three $Na^+$ ions out of the cell and pumps two $K^+$ ions into the cell against their respective concentration gradients.

Phagocytosis

A form of bulk endocytosis ("cell eating") wherein the plasma membrane extends pseudopodia to engulf large solid particles, such as microbes or debris, into internal vesicles.

Exocytosis

An active bulk export process in which cytoplasmic transport vesicles fuse with the plasma membrane to secrete substances such as hormones and export proteins or eliminate metabolic waste.

Surface Area-to-Volume Ratio

The geometric relationship that constrains cell size, dictating that as a cell grows, its volume increases faster than its membrane surface area, limiting transport capacity.