Cell locomotion

1. Endocytosis By Dr. Fatima Riaz

2. Transport across Cell Membrane Diffusion is the process of cells moving from areas of high concentration to areas of low concentration. This random movement causes the molecules to become evenly spread out.

3. Diffusion Cells use diffusion to get substances into and out of the cell. Example: During photosynthesis, oxygen is produced inside the cell. When this happens the concentration of oxygen becomes higher inside the cell than outside and oxygen diffuses out of the cell.

4. Osmosis is the diffusion of water through a membrane. Water moves into an area with low concentrations and out of areas with high concentrations. Both diffusion and osmosis are forms of passive transport (they require no energy)

5. Transport across Cell Membrane : Active Transport materials move from low concentration to high concentration. requires energy!

6. Endocytosis moving a particle into the cell Phagocytosis Pinocytosis Exocytosis: moving a particle from inside the cell to outside.

7. PINOCYTOSIS Ingestion of minute particles e.g protein molecules PHAGOCYTOSIS Ingestion of large particles, such as bacteria , whole cells or portions of degenerated tissue.

8. Mechanism of pinocytosis

9. Movement thru the Cell Membrane: Active Transport Endocytosis Exocytosis

10. Cell Locomotion Amoeboid movement Ciliary movement

11. Ameboid movement Movement of an entire cell in relation to its surroundings Involves pseudopodium and ATP Mechanism formation of new cell membrane & exocytosis at one end Attachment of pseudopodium to tissues Receptor proteins Absorption of the membrane & endocytosis in mid & rear portions Detachment of receptor proteins

12. Ameboid movement

13. Ameboid movement Cells that exhibit ameboid motion WBC Fibroblasts Embryonic cells Control of ameboid motion Chemotaxis Positive Negative

14. Cilia and Ciliary movements Whiplike movement of cilia on the surfaces of cells A sharp pointed hair projecting 2-4micrometers from the surface of the cell.

15. Structure of a cilium Covered by an outcropping of cell membrane Supported by 11 microtubules, 9 double tubules at the periphery and 2 single tubules down the center. Each cilium is an outgrowth of a structure that lies immediately beneath the cell membrane, called basal body of the cilium

16. All the tubules are linked to one another by a complex of protein cross linkages, together called the axoneme. Multiple protein arms composed of the protein dynein (having ATPase activity) project outward from each double tubule ATP and appropriate magnesium and calcium concentration required.

17. Mechanism of ciliary movement Sudden fast forward whip like stroke Slow backward stroke An effective way of pushing the fluid in the direction of forward stroke.

18. CELLS EXHIBITING CILIARY MOVEMENT 1- Respiratory airways 2- Uterine tubes of the female reproductive tract.

19. Q & A

20. Cell Growth and Division Multicellular organisms grow because cell division increases the number of cells in them. Cells become specialized during the development of an organism. Cells that are damaged or worn out are replaced by cell division.

21. Cell Growth and Division: The Cell Cycle Interphase: The part of the cell cycle when the cell is not dividing. This is the longest phase in the cell cycle. Cells grow and go about their daily routines in this part of the cycle. DNA (genetic material) replicates.

22. Cell Growth and Division: The Cell Cycle Mitosis: the part of the cell cycle where the nucleus divides. Occurs in non-reproductive cells and produces exact copies of the parent cell. Prophase: The chromosomes condense Metaphase: The chromosomes line up in the middle of the cell. Anaphase: The chromosomes separate and are pulled to either end of the cell. Telophase: The new nuclear membrane forms. Cytokinesis: The cell splits in half.

23. Cell Growth and Division: The Cell Cycle

24. Cell Growth and Division: The Cell Cycle Meiosis: The cell division that takes place within reproductive cells. Produces cells that only have one pair of chromosomes. Meiosis produces egg and sperm cells. Before meiosis begins, the chromosomes from the parent cell are copied.