Biology101 Chapter 3

Prokaryotic Cells

Cells without a nucleus and membrane-bound organelles; DNA is in a nucleoid region. Examples include bacteria and archaea.

Eukaryotic Cells

Cells with a nucleus containing DNA and membrane-bound organelles, such as mitochondria and ER. Examples include animals, plants, fungi, and protists.

Common Characteristics of Cells

All cells have a plasma membrane, cytoplasm, DNA as genetic material, and ribosomes for protein synthesis.

Chloroplasts

Organelles found in plant cells; site of photosynthesis.

Cell Wall

A rigid outer layer found in plant cells that provides structure and support.

Central Vacuole

A large organelle in plant cells that stores water and maintains turgor pressure.

Lysosomes

Organelles in animal cells that contain digestive enzymes.

Cilia

Short, numerous cellular structures that enable coordinated movement for locomotion or moving substances across surfaces.

Flagella

Long, fewer in number, propeller-like structures used for cell movement (e.g., sperm cells).

Centro some

Microtubule-organizing center involved in cell division, containing two centrioles.

Cell Junctions

Structures that connect cells; include tight junctions, desmosomes, and gap junctions.

Phagocytosis

The process by which a cell engulfs large particles or microorganisms, forming a phagosome that fuses with lysosomes.

Autophagy

The process of self-eating where damaged organelles or proteins are degraded to maintain cellular homeostasis.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts originated from ancient prokaryotes engulfed by ancestral eukaryotic cells.

Microfilaments

Thin, flexible fibers made of actin that function in cell shape, muscle contraction, and movement.

Intermediate Filaments

Rope-like fibers providing tensile strength, maintaining cell shape and anchoring organelles.

Microtubules

Hollow tubes made of tubulin, involved in cell division, intracellular transport, and movement.

Plasma Membrane

A phospholipid bilayer with embedded proteins that regulates the entry and exit of substances in the cell.

Mitochondria

Organelles that produce ATP (energy) through cellular respiration.

Golgi Apparatus

An organelle that modifies, sorts, and ships proteins.

Rough ER

The portion of the endoplasmic reticulum with ribosomes, involved in protein synthesis.

Smooth ER

The portion of the endoplasmic reticulum without ribosomes, involved in lipid synthesis and detoxification.

Nucleus

The organelle that stores DNA and controls the activities of the cell.

Extracellular Matrix (ECM)

A network of proteins outside animal cells that provides structural support, adhesion, and communication.

Vacuoles

Storage organelles; large central vacuoles in plants are primarily for water storage.

Cellular Communication

The process managed by the plasma membrane, which allows cells to interact and send signals.