Cell Transport

Passive Transport

• The movement of materials across the cell membrane WITHOUT using cellular energy is called PASSIVE TRANSPORT

Diffusion

• Describes the movement of particles through random motion from regions of HIGH concentration to regions of LOW concentration

Diffusion can only occur if there are different concentrations in and out of the cell.

If the amount going into the cell is equal to the amount going out of the cell there will be no net change...this is called EQUILIBRIUM

osmosis

• The diffusion of WATER across a selectively permeable membrane is called OSMOSIS

Facilitated diffusion

• Specific molecules are passed through a membrane by a protein without using energy.

HYPERTONIC

• A solution that has MORE solute concentration than inside the cell Water will move OUT of the cell causing the cell to SHRINK

hypotonic solution

• A solution has LESS solute concentration than inside the cell Water moves INTO the cell causing the cell to SWELL

isotonic

• A solution that has the SAME solute concentration as inside of the cell Water molecules will move in both directions equally.

active transport

• A means of particle transport that requires INPUT OF ENERGY from the cell

The active transport of small molecules or ions across a cell membrane is generally carried out by transport proteins, or protein "pumps" that are found in the membrane.

Larger molecules and clumps of material can also be actively transported across the cell membrane by processes known as endocytosis and exocytosis

endocytosis

• the process of taking material INTO the cell by means of infoldings, or pockets of the cell membrane.

2 Types of Endocytosis

• Phagocytosis- extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it.
• Pinocytosis- cell takes up liquid from surrounding environment by forming tiny pockets along the cell membrane.

exocytosis

• The membrane of the vacuole surrounding the material fuses with the cell membrane forcing the contents out of the cell.

The cells of multicellular organisms become specialized for particular tasks and communicate with one another to maintain homeostasis. (ex: blood cells, nerve cells, skin cells)

Levels of organization

• cell
• tissue
• organ
• organ system