(test monday 11/9/26) Comprehensive Biology Study Notes: Cell Structure, Membrane Transport, Intercellular Signaling, and Cell Cycle Regulation

A comprehensive vocabulary review deck covering cell membrane structure, transport mechanisms, signal transduction, the cell cycle, mitosis, binary fission, cancer pathology, and organelle morphology.

Amphipathic

Describes a molecule that has both a hydrophilic (water-loving) and a hydrophobic (water-fearing) component, such as membrane phospholipids.

Integral Proteins

Membrane proteins that run completely through the phospholipid bi-layer from the outside to the inside of the cell.

Peripheral Proteins

Membrane proteins located on the surface that do not extend through the bi-layer, attaching to the cytoskeleton on the inside or the extracellular matrix (ECM) on the outside.

Fluid Mosaic Model

A model of cell membrane structure where phospholipids form a moving fluid matrix and embedded proteins move laterally within it like a mosaic.

Glycolipids and Glycoproteins

Sugar-lipid and sugar-protein surface molecules that function in cell-to-cell recognition, acting like hands to identify molecules and adjacent cells.

Cholesterol

A lipid embedded in cell membranes that helps maintain membrane fluidity and prevents plant cell membranes from freezing solid in cold environments like the tundra.

Earl Sutherland

The scientist who won a Nobel Prize for elucidating the three-step pathway of cell communication: reception, transduction, and response.

Ligand

A chemical signaling molecule that binds specifically to a membrane receptor protein, initiating a conformational shape change.

Reception

The first stage of cell signaling where a chemical ligand binds to a specific membrane receptor protein.

Transduction

The second stage of cell signaling where the receptor conformational change converts the extracellular signal into an intracellular message the cell can interpret.

Response

The final stage of cell signaling where the intracellular signal pathway is completed and the cell performs the directed action.

Restriction Point

The primary cell cycle checkpoint located at the end of $G_1$ that serves as the definitive point of no return before replication.

$G_0$ Phase

The zeroth growth phase outside the regular cell cycle where Cyclin is not synthesized and cell division is completely shut down or turned off.

Cyclins

Regulatory molecules that control the timing and progression of the cell cycle through its checkpoints.

Benign Tumor

An encapsulated, non-invasive abnormal growth (resembling a tennis ball) that is usually non-fatal and easily treated via surgical removal.

Malignant Tumor

An invasive abnormal growth (meaning the crab) that destroys surrounding tissue, spreads throughout the body, and requires treatments like chemotherapy, radiation, surgery, immunotherapy, or CRISPR.

Osmosis

The passive diffusion of water across a membrane toward a higher concentration of solute particles.

Turgid

A condition in plant cells characterized by high internal water content, creating rigid cells and a stiff plant posture.

Flaccid

A condition in plant cells caused by insufficient water, resulting in limp cells and wilting of the plant.

Plasmolysis

The lethal process where a plant cell loses water, causing the plasma membrane to pull away and rip from the cell wall.

Active Transport

The movement of substances across a cell membrane against their concentration gradient, requiring energy input from $ATP$ via phosphorylation or from electron movement.

Phagocytosis

A form of bulk endocytosis described as cell eating, in which large molecules or particulate matter are taken into the cell.

Pinocytosis

A form of bulk endocytosis described as cell drinking, in which extracellular liquid droplets and dissolved solutes are engulfed.

Genome

The entire set of genetic material ($DNA$) of an organism or cell, measuring roughly $2\,m$ (or $7\,ft$) in length per human cell.

Chromatin

The uncoiled, loose state of $DNA$ resembling a bowl of spaghetti noodles, allowing access to specific gene sequences for protein synthesis.

Chromosomes

The tightly coiled, condensed corkscrew-shaped state of $DNA$ structured to divide genetic material equally and easily during mitosis.

Somatic Cells

Diploid ($2n$) body cells that make up the vast majority of an organism and replicate through ordinary mitosis.

Gametes

Haploid ($n$) sex cells containing half the total chromosomal complement ($n = 23$ in humans) produced through meiosis.

Histones

Structural proteins that aid in condensing and coiling $DNA$ into organized chromosomes for cell division.

Sister Chromatids

The two identical longitudinal halves of a duplicated chromosome formed during $S$ phase, joined together at the centromere.

Centromere

A specialized group of proteins that binds two sister chromatids together at the center unit of a replicated chromosome.

Binary Fission

The asexual reproductive division process in prokaryotes (bacteria) that replicates a single circular chromosome and divides the cytoplasm using an actin-myosin cleavage furrow.

Chloroplast

A double-membraned plant organelle consisting of thylakoids and stroma that contains its own $DNA$, ribosomes, and photosynthetic pigments to synthesize glucose.

Mitochondria

The powerhouse organelle found in both plant and animal cells that makes $ATP$ and possesses its own $DNA$, ribosomes, and enzymes.

Smooth Endoplasmic Reticulum

A membranous organelle made of cisternae located outside the nucleus that synthesizes lipids, breaks down carbohydrates, and detoxifies cellular poisons.

Rough Endoplasmic Reticulum

A cisternae-based organelle continuous with the nucleus that is studded with ribosomes and specializes in building and transporting proteins.

Golgi Apparatus

A stacked organelle formed from flattened cisternae that modifies, packages, and transports proteins to their destination.

Lysosome

A phospholipid-bound organelle found in animal cells containing digestive enzymes that functions as the stomach of the cell.

Nucleolus

A dense subnuclear region found inside the nucleus responsible for the synthesis of $RNA$ ($rRNA$, $mRNA$, and $tRNA$).

Ribosome

A non-membrane-bound cellular structure made of $RNA$ that carries out protein synthesis, occurring either free-floating in the cytoplasm or bound to the rough endoplasmic reticulum.

Cell Wall

A rigid protective and supportive layer made of cellulose located exterior to the cell membrane in plant cells.