2.4 : Cell Transport

Transcription

1 2.4 : Cell Transport At the end of the lesson, you should be able to : Explain the various transport mechanisms across the membrane : Active transport - Sodium-Potassium Pump Endocytosis and Exocytosis

2 ACTIVE TRANSPORT Require energy

3 ACTIVE TRANSPORT The movement of a substance across a cell membrane, with use of energy, against its concentration gradient, mediated by specific transport protein.

4 ACTIVE TRANSPORT Sodium potassium pump Translocates ions against concentration gradient. Features : Protein transportation between two conformation. K + binding site towards cell exterior Na + binding site towards cytoplasm

5 ACTIVE TRANSPORT Sodium potassium pump Translocates ions against concentration gradient. Features : ATP phosphorylates the transport protein powers the conformational from Na + receptive to K + receptive.

6 ACTIVE TRANSPORT Sodium potassium pump Binding sites in the sodium potassium pump have high-affinity to Sodium ions.

7 ACTIVE TRANSPORT Sodium potassium pump Sodium ions in cytoplasm bind to the protein stimulated phosphorylation by ATP.

8 ACTIVE TRANSPORT Sodium potassium pump Phosphorylation of ATP causes the protein to changes it conformation

9 ACTIVE TRANSPORT Sodium potassium pump The present of phosphate group reduce the affinity of protein binding sites to Na + and now the proteins binding sites has higher affinity to potassium ions. Na + dissociate to extracellular matrix and the extracellular K + bind to the protein.

10 ACTIVE TRANSPORT Sodium potassium pump K+ binding triggers release of phosphate group.

11 ACTIVE TRANSPORT Sodium potassium pump Loss of phosphate group restores protein original conformation [high affinity of Na+, low affinity to K+, face in cytoplasmic site.]

12 ACTIVE TRANSPORT Sodium potassium pump K+ is released into cytoplasm and Na+ sites will bind with the Na+

13 Sodium potassium pump

14 ACTIVE TRANSPORT Involves vesicle formation endocytosis exocytosis phagocytosis pinocytosis

15 ACTIVE TRANSPORT Endocytosis Plasma membrane invate. Form small vesicle/food vacuole. Phagocytosis engulfed large,solid particle. Pinocytosis the uptake of liquids by cell.

16 ACTIVE TRANSPORT Endocytosis Phagocytosis Engulfing cell detects the particles. The particles attached to the membrane of phagocytic cell.

17 ACTIVE TRANSPORT Endocytosis Phagocytosis The membrane of cell invaginate and form pseudopodia. Pseudopodia surround the particle. Cell engulfing the particle.

18 ACTIVE TRANSPORT Endocytosis Phagocytosis Phagosome (food vacuole) formed. Phagosome pinched off and move into the cytoplasm.

19 ACTIVE TRANSPORT Endocytosis Phagocytosis Phagosome fused with lysosome to digest the food particle.

20 ACTIVE TRANSPORT Endocytosis Phagocytosis Products absorbed, vacuole disappeared Undigested content- egested through reverse prosess (exocytosis)

21

22 ACTIVE TRANSPORT Endocytosis Pinocytosis The cytoplasmic membrane invaginates and pinches off placing small droplets of fluid in a pinocytic vesicle.

23 ACTIVE TRANSPORT Endocytosis Pinocytosis The liquid contents of the vesicle is then slowly transferred to the cytosol.

24 Pinocytosis

25

26 Involves vesicle formation endocytosis exocytosis Phagocytosis e.g. : engulfing of bacteria by the macrophage Pinocytosis e.g. : taking of dissolved solutes by absorptive cells of the kidney and intestines

27 ACTIVE TRANSPORT Exocytosis The vesicle membrane becomes incorporated into the cell surface membrane.

28 ACTIVE TRANSPORT Exocytosis The contents in the vesicle are released outside the cell.

29 ACTIVE TRANSPORT Exocytosis E.g : The secretion of enzymes from pancreatic cells or hormones from endocrine glands.

30

31

32

33

34 End of Cell Transport