Cell Structure and Function

Vocabulary practice flashcards based on Chapter 3 lecture notes covering cell theory, cellular microscopy, cell shape and size dynamics, plasma membrane structure, and membrane protein functions.

Robert Hooke

The scientist who observed cork plant tissue in 1665 and coined the term "cell."

Theodor Schwann

The scientist who concluded in the 1800s that all animals are made of cells, establishing the concept that all organisms are composed of cells.

Louis Pasteur

The scientist who disproved spontaneous generation circa 1859 through work with bacteria, establishing that cells arise only from preexisting cells.

Cell Theory

The foundational theory stating that all organisms are composed of cells, the cell is the simplest structural and functional unit of life, organismal function depends on cellular activity, cells come from preexisting cells, and all species share fundamental cellular similarities.

Resolution

The ability of an optical instrument or human eye to reveal fine structural detail.

Naked Eye Resolution

The resolution limit of the human eye without magnification, which is approximately $100\text{ }\frac{1}{1000}\text{ mm}$ or 100\text{ }\text{̧}\text{...} (100\text{ }\text{̧}\text{...}) 100\,̧\mu m.

Light Microscope Resolution

An optical microscope with a resolution limit of $200\,nm$, capable of revealing the surface membrane, nucleus, and cytoplasm.

Electron Microscope Resolution

An imaging microscope with a resolution limit of $1\,nm$, capable of revealing detailed cell ultrastructures within the cytoplasm.

Cell Shapes

The varied morphological configurations of cells, including squamous, polygonal, cuboidal, columnar, spheroid, discoid, stellate, fusiform (spindle-shaped), and fibrous forms.

Human Cell Size Range

Most human cells range from 10\,̧\mu m to 15\,̧\mu m in diameter, with egg cells reaching 100\,̧\mu m, muscle cells up to $30\,cm$ long, and nerve cells over $1\,m$ long.

Surface Area to Volume Relationship

As cell diameter increases by a factor of 2, its surface area increases by a factor of 4 ($D^2$) while its volume increases by a factor of 8 ($D^3$).

Cell Size Constraint

The physiological limitation where a cell that grows too large has too little plasma membrane to serve the metabolic needs of its increased volume.

Plasma Membrane

A cellular envelope appearing as a pair of dark parallel lines approximately $7.5\,nm$ thick that defines cell boundaries, controls inter-cellular interactions, and regulates material transport.

Cytoplasm

The interior cell content including cytosol (intracellular fluid/ICF), organelles, and the cytoskeleton.

Extracellular Fluid (ECF)

The fluid located outside of the plasma membrane of a cell.

Typical Cell Structure

A generalized cell diagram showing major organelles, cytosol, microvilli on the apical surface, lateral surfaces, and basement membrane at the basal surface.

Ultrastructure of a White Blood Cell

An electron micrograph showing internal subcellular organelles of a leukocyte, including the nucleus, nuclear envelope, mitochondria, Golgi complex, Golgi vesicles, and ribosomes.

Fluid Mosaic Model

The model of plasma membrane structure consisting of a phospholipid bilayer embedded with proteins, cholesterol, glycolipids, and glycoproteins.

Phospholipid Bilayer

The primary lipid constituent making up 75% of plasma membrane lipids, arranged with hydrophilic polar heads on the outer surfaces and hydrophobic nonpolar tails in the center.

Membrane Cholesterol

Lipid molecules constituting 20% of plasma membrane lipids that intercalate among phospholipids to regulate membrane fluidity.

Glycolipids

Lipids with attached carbohydrate chains making up 5% of membrane lipids, located on the extracellular face to help form the glycocalyx.

Integral Proteins

Transmembrane proteins (mostly glycoproteins) that pass entirely through the plasma membrane and can drift within the bilayer or anchor to the cytoskeleton.

Peripheral Proteins

Membrane proteins that do not enter the phospholipid bilayer but adhere to one face of the membrane, usually attached to transmembrane proteins or the cytoskeleton.

Membrane Protein Functions

The main functional roles of cell surface proteins, including serving as receptors, enzymes, ion channels, gated ion channels, cell-identity markers, and cell-adhesion molecules (CAMs).

Receptor (Membrane Protein)

A cell surface protein that binds specific extracellular chemical messengers, such as hormones, to trigger intracellular responses.

Enzyme (Membrane Protein)

A membrane protein that catalyzes specific chemical reactions at the cell surface, such as breaking down chemical messengers or substrates.

Ion Channel

A membrane protein or pore that allows specific ions to pass constantly across the plasma membrane.

Gated Ion Channel

A membrane protein channel that opens and closes in response to specific stimuli to regulate ion flux across the plasma membrane.

Cell-Identity Marker

A surface glycoprotein or glycolipid that acts as an identification tag allowing the body to distinguish self cells from foreign entities.

Cell-Adhesion Molecule (CAM)

A membrane protein that binds one cell to another cell or to extracellular materials.