Cell Membrane and Active Transport

Active Transport in the Cell Membrane 

Active transport 

• Uses energy in the form of ATP

• Goes AGAINST the concentration gradient (Low to High)

3 ways

• Protein pumps (Sodium Potassium Pump [Na+ and K+])

• Endocytosis (entering the cell) also (Pinocytosis)

• Exocytosis (exiting the cell)

• Endocytosis and exocytosis (BULK TRANSPORT, things moving in bulk transport)

Active transport 

• Cell uses energy 

• Actively moves molecules to where they are needed 

Protein pumps

• Transports proteins that require energy to do work

• Ex:Sodium Potassium pumps are important in nerve responses 

• Protein changes shape to move molecules.  This requires energy 

• Sodium and potassium binding sites 

• 1 phosphate comes off the ATP to help change shape 

• Only 3 Na can be moved at a time (1 phosphate is attached)

• Then the 2 K is moved (phosphate is then detached is left)

• So 3 leave, 2 enter cell, 1 phosphate is attached on the inside, then detached when done

• Because of the uneven ratio 3:2, it creates a concentration electrical gradient 

Endocytosis 

• Taking things into the cell

• The Cell membrane in-folds around the food particle, or engulfs 

• Cell eating (Phagocytosis) (immune response nutrient uptake mostly common  immune cell)

• Cell drinking (Pinocytosis)(Immune surveillance nutrient uptake, almost all cell types)

• Bulk transport in, food or liquid form into the actual cell

• This is how white blood cells eat, how they fight infections

Exocytosis

• Forces material out of cell in bulk

• Membrane surrounding the material fuses with the cell membrane 

• Cell changes shape 

• Requires energy

• Hormones Or wastes released from cell

• A neuron is a nerve cell, space between 2 nerve cells is called the synapse