Tsaren Posted March 10, 2012 Report Share Posted March 10, 2012 Hello , I was wondering what the difference between Antigen, pathogen and antibody are?/Thanks for respond Reply Link to post Share on other sites More sharing options...
Guest Jar Jar D'oh! Posted March 10, 2012 Report Share Posted March 10, 2012 Hello! That's easy: An Antigen is a protein molecule on the surface of all invading biochemical molecules (other molecules also have projected proteins, but the ones on the 'bad guys' are called Antigens). It serves the purpose of helping the body identify molecules as self- from the body or non-self- from outside the body. Common practice refers to Antigens mainly as the poteins projected on the coats of viruses, pathogens etc. and these proteins elicit an immune response. Antibody- is a Y-shaped chemical that is produced my I forgot who so I'll just say WBCs. There are hundred thousand Antibodies and each antibody is specific to a single antigen, like one jigsaw piece that one fits one particular dent/ hole. This could use further explaining. Pathogens are invading organisms, that are non-self and harm the body. Cheers! Reply Link to post Share on other sites More sharing options...
Mahuta ♥ Posted March 10, 2012 Report Share Posted March 10, 2012 Pathogen as given in the syllabus: an organism or a virus that causes a disease. Basically anything that can make you sick. Antigens: These are any substances that trigger the production of antibodies. An antibody is only produced when the WBC (lymphocyte) recognizes a specific antigen. (I'll explain below). Antibodies: These are what the body (WBC) produces to fight that antigen. Think about it this way, when an antigen is going around the body causing all sorts of different problems, you need to fight it so you call those Lymphocytes. However, not all lymphocytes recognize that, so they would all try to fit that antigen onto their receptors (just an antigen binding site), if it fits, then they are stimulated (the lymphocytes) which means the body recognized this as an invador. It starts producing antibodies that are going to fight it. Note that a specific antigen only fits on specific lymphocytes. I am not sure all that made sense, but I used my imagination. 1 Reply Link to post Share on other sites More sharing options...
Sandwich Posted March 10, 2012 Report Share Posted March 10, 2012 Hello , I was wondering what the difference between Antigen, pathogen and antibody are? /Thanks for respond To give a slightly more specific set of answers that slightly alter details given by previous posters: Antigen: a molecule that triggers an adaptive immune response. This doesn't necessarily always involve the production of antibodies, although that is one possible outcome. There are many ways besides antibodies that the adaptive immune response may take action, including generation of killer cells etc. Antigens also aren't necessarily on invading pathogens - they CAN be, but they could also be elsewhere. You can in fact (through a failure to delete these cells during development, or a failure to stop them from working peripherally - a process known as tolerance) have adaptive immune cells that respond to your molecules on your OWN cells. Or to things you don't actually want to respond to (e.g. grass pollen, which isn't an invading pathogen...). This is the basis for autoimmune disease, allergy etc. So whilst the body is MEANT to (and generally does) recognise only foreign molecules as antigen to generate an adaptive immune response, it can also recognise itself (self-antigen) and non-pathogenic molecules. Also, the molecules it recognises don't have to be extracellular on the cell surface (this is only necessarily for antibody-type adaptive immune responses), they can also be intracellular (what happens is the cell chomps up the intracellular proteins and then displays them on its surface, so killer cells can come along, recognise it, and destroy the cell). If you think about it, this must be the case because viruses don't live on the outside of cells - only inside! So we'd all die of viral disease if intracellular things couldn't be recognised as well. Antibody: these are part of the adaptive immune response. These are Y shaped proteins produced by B Cells (which are categorised as lymphocytes, which are categorised as white blood cells - WBCs - just to make that clear) and they consist of are two parts. Part of it is for recruiting other cells, molecules etc. to come along and help to destroy the cell which is affected (the body sees cells displaying antigen as bad and to be killed). The other part is special in shape and designed to recognise a specific antigen. A bit like the lock and key enzyme theory. When antibodies encounter that antigen, they bind to it - and then that first part (the recruiting part) gets recruiting many other powerful things like killer cells, inflammatory mediators etc. and the immune response goes on from there. These are very complex things and there's tonnes to know about them, but obviously you don't need to know it all for IB Probably just that antibodies are made by B Cells and 'stick' onto the antigen they are specific for, and that an antigen is a molecule that triggers an adaptive immune response. Pathogen: exactly what Mahuta said 2 Reply Link to post Share on other sites More sharing options...
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