Cells, Membrane, and Transport

Cell Theory

States that all organisms are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells.

Prokaryotic Cells

Structurally simpler cells that lack a membrane-bound nucleus; includes bacteria and archaea.

Eukaryotic Cells

More complex cells that have a true nucleus and organelles, including protists, plants, fungi, and animals.

Plasma Membrane

A selective barrier that regulates what enters and leaves the cell, composed of a phospholipid bilayer.

Mitochondria

Organelles known as the powerhouse of the cell that carry out cellular respiration to convert food into ATP.

Chloroplasts

Organelles in plant cells that convert solar energy into chemical energy through photosynthesis.

Rough Endoplasmic Reticulum

Part of the endoplasmic reticulum studded with ribosomes, synthesizes and modifies proteins.

Smooth Endoplasmic Reticulum

Part of the endoplasmic reticulum that synthesizes lipids and detoxifies drugs.

Lysosomes

Sacs of enzymes that digest macromolecules, old organelles, and foreign substances.

Vacuoles

Storage structures in cells, particularly prominent in plant cells for maintaining turgor pressure.

Cytoskeleton

A network of fibers that helps maintain cell shape and aids in cell movement and transport of materials within the cell.

Osmoregulation

The control of water balance within a cell or organism.

Endocytosis

A process in which the cell membrane engulfs material from outside the cell, bringing it inside.

Exocytosis

A process in which materials inside the cell are packaged into vesicles and expelled to the outside.

Passive Transport

The movement of substances across a cell membrane without energy input, following a concentration gradient.

Active Transport

The movement of substances against their concentration gradient, requiring energy (ATP) input.

Isotonic Solution

A solution where the solute concentration is equal inside and outside the cell, resulting in no net movement of water.

Hypotonic Solution

A solution where the solute concentration is lower outside the cell, causing the cell to gain water.

Hypertonic Solution

A solution where the solute concentration is higher outside the cell, causing the cell to lose water.

Cell Wall

A rigid structure that surrounds and protects plant cells, maintaining shape and providing structural support.

Ribosomes

Cellular structures that synthesize proteins by translating mRNA.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.