Cellular Form and Function

Cytology

The scientific study of cells.

Cell Theory

A fundamental concept stating that all organisms are composed of cells, the cell is the simplest unit of life, and all cells arise from preexisting cells.

Phospholipids

Amphiphilic molecules that make up 75% of membrane lipids, arranged in a bilayer with hydrophilic heads facing water.

Glycocalyx

Carbohydrate coating on the cell surface that helps with protection, immunity, and cell adhesion.

Endocytosis

Vesicular process that brings material into the cell.

Exocytosis

Vesicular process that discharges material from the cell.

Osmosis

Flow of water through a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.

Hypotonic Solution

A solution with a lower concentration of nonpermeating solutes than intracellular fluid, causing cells to swell.

Active Transport

A form of transport that requires energy (ATP) to move substances against their concentration gradient.

Aquaporins

Channel proteins specialized for the passage of water across the plasma membrane.

Facilitated Diffusion

Carrier-mediated transport of solute through a membrane down its concentration gradient without the use of ATP.

Rough Endoplasmic Reticulum (RER)

A type of ER that has ribosomes on its surface and synthesizes proteins.

Smooth Endoplasmic Reticulum (SER)

A type of ER that lacks ribosomes and synthesizes lipids and detoxifies harmful substances.

Mitochondria

Organelles specialized in ATP synthesis, often referred to as the powerhouses of the cell.

Centrioles

Short cylindrical structures that play a role in cell division, forming the mitotic spindle.

Lysosomes

Membrane-bound organelles containing enzymes for intracellular digestion.

Transmembrane Proteins

Proteins that pass through the plasma membrane and have both hydrophilic and hydrophobic regions.

Channel Proteins

Transmembrane proteins with pores that allow water and dissolved ions to pass through the membrane.

Nucleus

The largest organelle, which contains the cell's genetic material and directs protein synthesis.

Gated Ion Channel

A channel protein that opens and closes to allow ions through only at certain times.

Cell-Identity Markers

Glycoproteins on the cell surface that distinguish the body's own cells from foreign cells.

Microvilli

Extensions of the plasma membrane that increase the surface area for absorption.