Active Transport

active transport

requires energy to transport across cell membrane

involves moving molecules against a concentration gradient

ATP

adenosine triphosphate

a nucleotide

ATP conversion

converts to ADP and releases energy and an inorganic phosphate (Pi) molecule

the energy is available for cell processes e.g. muscle contraction

ADP

adenosine diphosphate

what does ATP release when converted?

energy

what is the energy released from ATP used for?

cell processes e.g. muscle contraction

sodium-potassium pump process

1. Na-K pump binds 3 sodium ions and a molecule of ATP

2. the splitting of ATP provides energy to change the shape of the channel. The Na+ are driven through the channel

3. Na+ are released on the outside of the membrane and the new shape of the channel allows 2 K+ to bind

4. Release of the phosphate allows the channel to revert to its original form, releasing the K+’s on the inside of the membrane

movement of substance in a Na-K pump

move from a lower to higher concentration

energy is gained through respiration in the form of ATP

types of active transport

endocytosis, exocytosis, phagocytosis, pinocytosis

endocytosis

‘into the cell’

important because most molecules needed for cell to survive cannot normally pass through the plasma membrane

phagocytosis and pinocytosis are types of endocytosis

types of endocytosis

phagocytosis and pinocytosis

exocytosis

‘out of the cell’

material is exported out of the cell via secretory vesicles

important in removing waste materials from the cell and in secreting cellular products e.g. enzymes or hormones

exocytosis process diagram

phagocytosis

cell’s plasma membrane surrounds a molecule, e.g. a food particle, in the extracellular environment and buds off to form a vacuole that contains the molecule. The molecule is then digested by enzymes

pinocytosis

cell’s plasma membrane surrounds droplets of fluid containing dissolved solutes, in the extracellular environment and buds off to form a vacuole that contains the molecule. The molecule is then digested by enzymes

pinocytosis process diagram