crossing cell membrane

Prokaryotes

Organisms lacking a nucleus with DNA in the cytoplasm, smaller than eukaryotes.

Eukaryotes

Organisms with a nucleus, membrane-bound organelles, and larger than prokaryotes.

Plasma Membrane Functions

Acts as a selective boundary, maintains cell identity, receives external signals, and transports materials.

Simple Diffusion

Passive transport from high to low concentration without energy.

Osmosis

Movement of water across a semi-permeable membrane from low to high solute concentration.

Isotonic Solution

No net movement across the membrane, maintaining normal cell shape.

Hypotonic Solution

Net movement of water into the cell, causing swelling in plant cells and lysis in animal cells.

Hypertonic Solution

Net movement of water out of the cell, leading to cell shrinkage or plasmolysis in plant cells.

Facilitated Diffusion

Movement from high to low concentration through proteins without energy.

Active Transport

Requires ATP to move molecules against the concentration gradient, e.g., Na+/K+ pump.

Bulk Transport

ATP-dependent movement of large molecules in and out of the cell.

Endocytosis

Process where substances enter the cell without crossing the membrane, including phagocytosis and pinocytosis.

Exocytosis

Process where substances exit the cell without crossing the membrane via Golgi-derived vesicles fusion with the plasma membrane.