Phagocytosis

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blackmangoes
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Phagocytosis

Post by blackmangoes » Tue Nov 15, 2005 4:51 am

What is the difference between phagocytosis and receptor mediated phagocytosis?
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phagocytosis

Post by lara » Tue Nov 15, 2005 5:07 am

Receptor mediated endocytosis is a process by which cells internalize molecules or viruses. As its name implies, it depends on the interaction of that molecule with a specific binding protein in the cell membrane called a receptor. Normally the receptor is clathrin coated pits.these receptors are absent in normal phagocytosis. Phagocytosis ("cell eating"):
results in the ingestion of particulate matter (e.g., bacteria) from the ECF.
The endosome is so large that it is called a phagosome or vacuole.
Phagocytosis occurs only in certain specialized cells (e.g., neutrophils, macrophages, the amoeba), and
occurs sporadically.
Receptor-Mediated Endocytosis
Some of the integral membrane proteins that a cell displays at its surface are receptors for particular components of the ECF. For example, iron is transported in the blood complexed to a protein called transferrin. Cells have receptors for transferrin on their surface. When these receptors encounter a molecule of transferrin, they bind tightly to it. The complex of transferrin and its receptor is then engulfed by endocytosis. Ultimately, the iron is released into the cytosol.clathrin occurs as triskelion.

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Post by MrMistery » Tue Nov 15, 2005 9:26 pm

lara is right. but i am curious about your question that mentiones "receptor mediated phagocytosis" and not receptor mediated endocytosis(which is probably what the teacher wanted). although none of my books say anything about receptor mediated phagocytosis the amoeba can make a difference between food and non-food. How is that done?
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Post by lara » Wed Nov 16, 2005 7:56 am

Endocytosis
The process by which a cell engulfs material to bring it into the cell is called endocytosis. Two major forms of endocytosis are:

Phagocytosis

Phagocytosis refers to the process of engulfing large particles.

so, if large particles are taken in with the help of receptors can v call it rreceptor mediated phagocytosis??

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Post by MrMistery » Wed Nov 16, 2005 7:25 pm

That is what you will find in a 30 year-old book(that phagocytosis and pinocytosis are types of endocytosis). the currect opion restricts phagocytosis to taking large particles or whole cells from the environment by creating cellular extensions by using polimerisation of actin molecules
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Post by blackmangoes » Thu Nov 17, 2005 1:12 am

You guys are pretty hardcore.

I would expect in order for the cell to engulf the particle, the cell needs to know the particle is around in the first place. The only way it knows that is to have the particle bind with a certain receptor.

Unless, you are telling me that the cell engulf the large particle without any receptor, and the particle they are engulf is non specific for normal phagocytosis....

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phagocytosis

Post by lara » Thu Nov 17, 2005 7:52 am

seems u forgot to read in your 30-year old textbook that receptor mediated phagocytosis(not endocytosis too occur in bacteriaI"would expect in order for the cell to engulf the particle, the cell needs to know the particle is around in the first place. The only way it knows that is to have the particle bind with a certain receptor" xactly!!
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Post by MrMistery » Thu Nov 17, 2005 7:35 pm

Yeah, but is that part of phagocytosis? And if it is, what is non-receptor mediated phagocytosis?
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Post by blackmangoes » Fri Nov 18, 2005 9:06 am

So what is the difference then? They both need receptor don't they?

I don't recall I have a 30 years old textbook hehe

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Post by Poison » Fri Nov 18, 2005 12:01 pm

It is "receptor mediated endocytosis". In receptor mediated endocytosis the material should be specific. Means not all of the cells can get everything. An extracellular material called ligand is links to the receptor, forms a ligand-receptor complex. (examples of ligands: LDL, transferrin) The vesicle is covered with a protein membrane-like structure. Then taken into the cytosol. Then carried to the lysosome.
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Post by MrMistery » Fri Nov 18, 2005 7:16 pm

Yeah, we all know that ozge. the formation of a clatrin coatet vesicle. but what about phagosytosis? Can there be receptor mediated phagocytosis and non-receptor mediated phagocytosis?
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Post by Poison » Sun Nov 20, 2005 5:15 pm

I tried to say that I haven't heard about it.
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