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.
12. 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
15. Ameboid movement
• Cells that exhibit ameboid motion
– WBC
– Fibroblasts
– Embryonic cells
• Control of ameboid motion
– Chemotaxis
• Positive
• Negative
16.
17. 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.
18. 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
19.
20. • 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.
21. 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.
22.
23. • CELLS EXHIBITING CILIARY MOVEMENT
• 1- Respiratory airways
• 2- Uterine tubes of the female reproductive
tract.
