cell membrane
TRANSCRIPT
Cell membraneThe transport and modification of
the cell
Present by Saad Sami Almuhanna
Learning objective
• What are the different Mechanisms responsible of transport?
• How the large molecules transport out from and into the cell ?
• What are the Modifications, their functions, examples ?
Mechanism of transport
• Passive transport• Active transport
Passive transport
1.Diffusion
2. Facilitated diffusion
3. Osmosis
Diffusion
Movement from high concentration to low concentration.
Facilitated diffusion• Channel proteins Provide corridors that allow a specific molecule or ion to cross the membrane.• Carrier proteins Undergo a subtle change in shape that translocate the salute-binding site across the membrane.
Osmosis• The movement of water across a semi permeable
membrane. • Osmosis is the movement of water (red dots) through a
semipermeable membrane to a higher concentration of solutes (blue dots).
Active transport
Process that moves materials across the plasma membrane
Requires energy from the cell in the form of ATP
Materials move against the concentration gradient:
low concentration high concentration
3 Kinds:Pumps, Endocytosis, and Exocytosis
Active Transport Pumps
1. An ATP molecule breaks down into ADP, releasing a phosphate group and a whole lot of energy.
2. The phosphate group attaches to a protein pump, causing it to change its shape so that it can move a small molecule or ion across the plasma membrane.
3. The protein changes shape again so that the molecule can be released on the other side.
There are many types of carrier proteins and they only carry specific molecules across the plasma membrane.
large molecules transportLarger molecules cannot fit. Because they are too big so they enter the cell by endocytosis and go out by exocytosis
Larger materials transport into the cell it is includes three slightly different processes:
Endocytosis:-
1. Phagocytosis: cell eating2. Pinocytosis: cell drinking3. Receptor mediated endocytosis
1. Phagocytosis:-endocytosis of solid particles.- cell engulfs particle with pseudopodia and pinches off a food vacuole- vacuole fuses with a lysosome containing hydrolytic enzymes that will
digest the particle2. pinocytosis:-fluid droplets of extracellular fluid are incorporated into small vesiclesthe process is not discriminating. the cell takes in all solutes dissolved in the droplet3. receptor-mediated endocytosis:- - cells have receptors for certain molecules on their surface. when these receptors encounter t molecule, they bind tightly to it. the complex of the molecule and its receptor is then engulfed by endocytosis. - a molecule that binds to specific receptor site of another molecule is called a ligand.
Exocytosis:-
The movement of material out of the cell via membranous vesicles
The modification and their function
Modification
apical lateral basal
1. Apical surface
its tissue of cell membrane on toward the lumen, there are many examples of apical
- stereocilia
- cilia
- flagella
- microvilli
stereocilia
Its function is
increase the cells surface area, facilitating the movement of molecules into and out to the cell
Its can be found in
the lining of the epididymis
Its function is
Its can be found in
cilia
trapping the materials to protect them
the lining of the trachea ( windpipe)
Its function is
Its can be found in
microvilli
reflecting cytoplasmic movement that will increase the total surface area of cells
kidney and intestines
Its function is
Its can be found in
flagella
it concerned with movement
in some certain eukaryotesEX. sperms in humans
2.lateral
it is a kind of protein which joins between adjacent cells within epithelium
these proteins have four types of junction:• tight junction• gap junction• adherens junction• desmosome
to form seal that prevents the flow of materials between epithelial cells in either direction.- help prevent the integral membrane proteins of the apical surface from being transferred
Tight junction
epithelial cells in general, brain cells
Function:
Examples
permit the rapid exchange between cells of molecules with small diameters
Function:
Examples
they are relevant in signal transfers in the brain
Gap junction
unction provide strong mechanical attachments between adjacent cells (provide for firm adhesion of one cell to its neighbors )
Function:
Examples
Adhering junction
present in narrow bands connecting adjacent cells or discrete patches holding the cells together
Desmosome
desmosome provide firm adhesion among the cells
Function:
Examples
Skin cells
3- Basal
its a friction of the plasma membrane at the basal side, which faces the underlying connective tissue
Example of Basal
polarity
Basal lamina
polarity
in cells, polarity refers to the asymmetric organization of different aspects of the cell including the cell surface, intracellular organelles and the cytoskeleton
Basal Lamina
Basal Lamina acts as base where the cells in the body can grow. It links cells together and underlies connective tissue.
Thanks for lessening