Cellular Biology and Homeostasis (4) “Active Transport” · Endocytosis • A Specialized form of Active Transport • Used to transport molecules that are too big to pass through

Unit #1: Wellness And Homeostasis

Cellular Biology and Homeostasis (4)

“Active Transport”

Active Transport

• A Method of transporting material into (or

out of) a cell AGAINST its concentration

gradient.

• Molecules are moved from an area of

LOWER concentration to an area of

HIGHER concentration

• This type of transportation requires

Energy

– The energy comes from energetic ATP

(Adenosine Tri-Phosphate) molecules

produced in the Mitochondria.

– An ATP molecule is broken down into

an ADP molecule and a phosphate ion.

This reaction releases 7kCal (7000

calories) of energy

How it Works 1. A Solute Molecule binds to a

special membrane protein

called a transport protein

2. An ATP molecule binds to the

transport protein giving it the

energy to move the Solute

molecule AGAINST the

concentration gradient and

across the cell membrane

3. The Solute Molecule is

deposited on the other side of

the cell membrane

Endocytosis • A Specialized form of Active Transport

• Used to transport molecules that are too

big to pass through a transport protein

(ex. Polypeptides, Polysaccharides)

• Molecules will bind to receptors

(Glycoproteins) on the surface of the cell

membrane which triggers the membrane to

fold inwards

• The membrane then pinches off forming a

VESICLE

• The vesicle then travels to the appropriate

organelle

There are

2 Types of Endocytosis

1. Phagocytosis (“Cell Eating”)

– Endocytosis of larger solid

molecules and material

– The vesicle created will have larger

amounts of solid material

2. Pinocytosis (“Cell Drinking”)

– Endocytosis of liquid material such

as dissolved nutrients and other

solutes

Exocytosis• Another Specialized form of Active

Transport

• Used to EXPORT molecules that are

too big to pass through a transport

protein (ex. Proteins, Hormones, Waste

Material)

• Molecules will bind to receptors

(Glycoproteins) on the inner surface of

the cell membrane which triggers the

membrane to fold outwards

• The membrane then pinches off forming

a VESICLE

• The vesicle then travels to the

appropriate target