so an antigen is a large protein molecule often found as a glycoprotein as part of a cell membrane or it can be found as part of a cell wall and they are used to identify cells and in this case we are showing you the structure of the cell membrane and the glycoprotein that might be used as an antigen to identify a specific bacterium antigens are genetically controlled so two closely related cells will have more similar antigens than unrelated cells antibodies on the other hand are secreted by a specific kind of lymphocyte called a b-cell antibodies are a kind of a y-shaped protein molecule and at the ends up here that we're indicating you have two binding sites these sites are used to bind with the antigens that you might find on foreign bacteria for example that enter the body and therefore a gluten ate the bacteria together forming like a clump bacteria at this point the agglutinative bacteria can be identified engulfed and digested by phagocytic leukocytes so you should see standard six point three point four for this final point to note is that specific antibodies bind with specific antigens