Cell Structures and Processes: Mitochondria, Nucleus, and Membrane Dynamics

Mitochondria

The 'powerhouse' of the cell; double-membrane structures where ATP is generated.

ATP

An organic molecule that transfers energy used in cellular processes.

Lysosomes

Tiny sacs containing digestive enzymes to break down waste and debris.

Peroxisomes

Sacs containing enzymes that catalyze metabolic reactions and detoxify alcohol.

Nucleus vs. Nucleolus

The nucleus houses DNA; the nucleolus is a small body inside the nucleus that produces ribosomes.

Passive Processes

Movement of molecules that does not require cellular energy (e.g., diffusion, osmosis).

Active Processes

Movement of molecules requiring cellular energy (ATP) to move substances against a gradient.

Hypertonic Solution

A solution with a higher osmotic pressure than body fluids; causes cells to shrink (lose water).

Hypotonic Solution

A solution with lower osmotic pressure; causes cells to swell and potentially burst (gain water).

Isotonic Solution

A solution with the same osmotic pressure as body fluids; cell size remains unchanged.

Basic unit of life

The cell is the basic unit of structure and function in the human body.

Differentiated

Cells that have specialized characteristics in structure and function.

Three major cell parts

Nucleus, cytoplasm, and cell membrane.

Organelle

A specialized structure within a cell that performs a specific function.

Selectively permeable

A property of the cell membrane that allows only certain substances to enter or leave the cell.

Cell membrane composition

Primarily a bilayer of phospholipids with embedded proteins and cholesterol.

Ribosomes

Sites of protein synthesis; found floating in the cytoplasm or attached to the rough ER.

Rough ER

Endoplasmic reticulum studded with ribosomes; functions in protein synthesis and transport.

Smooth ER

Endoplasmic reticulum lacking ribosomes; functions in lipid synthesis and detoxification.

Golgi Apparatus

A stack of flattened sacs that refines, packages, and delivers proteins.