Antibodies Structure and Functions | Immune System – Biology with GeeklyEDU

hi and welcome to today's video where 
we will be discussing antibody structure   and function within our immune system. specifically, in this video we are going to be 
talking about the adaptive immune system. if you   want to learn more about the difference between 
the innate and adaptive immune system you can   find the video called elements of immunology 
but today we're going to talk about specifically   antigens and antibodies within the adaptive immune 
system so within this part of our immune system we   have to be able to target specific pathogens 
and to do this our immune cells recognize   things called antigens or they're also called 
immunogens antigens are a specific molecule that's   present on the outsides of pathogens such as 
viruses bacteria or fungi so in this figure here   we have a virus and these little protrusions here 
would be our antigens on the outside of the virus and then what our immune cells will do is our 
immune cells have things called antibodies or   immunoglobulins and antibodies will look for and 
attach themselves to the antigens and then once   they bind to the antigens they signal for other 
immune cells to come and attack so here in this   figure we see in the blue we have our antibodies 
and the antibody here is bound to the antigen   and then this will then signal the alarm 
for other cells to come and kill the virus specifically antibodies are composed of 
this structure which looks like a y shape   and this structure helps with its function 
so the first function of the antibody is to   bind to antigens and so this top part of 
the antibody the top part of the y is the   fragment antigen binding or the fab fragments 
and so this is where it binds to the antigen   the second function of an antibody is 
to then activate activate the defense so   signal the alarm for other immune cells to 
come and kill the pathogen and this is where   the the bottom part of the y or the fragment 
crystallizable region or fc region is important looking a little bit deeper into the antibody 
structure antibodies are composed of four   polypeptides and a polypeptide is a formation 
or a string of amino acids amino acids are the   building blocks for proteins and specifically 
antibodies are made of two light chains   and two heavy chains and so these two light 
and two heavy chains form the four polypeptides   and so here in red we have the heavy chains 
and then in purple we have the two light chains on top of that antibodies have both 
a constant and a variable region   so here in the darker shade of purple and red 
we have the constant region of the antibody and   then in the light purple or the light red we 
have the variable region and so this variable   variable region will change or be very 
diverse between the different antibodies   as they're aimed at targeting 
a different range of pathogens   so to be able to specifically target different 
pathogens it has these highly variable regions within the fab fragment that i just mentioned 
so this top part of the antibody we have   the both the variable region in 
both chains and the constant region   but the fc region is just made of the constant 
region of the heavy chain and so this is the part   of the antibody that is usually interacting or 
within the cell membrane of our own immune cells now antibodies come in five main forms 
or families and they are the igg igm iga   ige and igd and they mainly differ in 
the type of heavy chain that is used   so while they each have at their core this y 
shape the y shape can be composed or created into   other shapes such as shown here and here 
and they're also usually found in different   parts of the body and while these antibodies are 
specifically aimed at fighting different pathogens   they can be generated at the same time or they can 
also be generated at different time points of your   same immune response so you have a pathogen maybe 
one antibody will be generated and then another   we will then be generated afterwards 
as part of the same immune response   and so really we have this very diverse um form 
to act against defense against all these different   specific pathogens such as certain viruses and 
bacteria and this is constantly evolving within   our bodies and so it's quite amazing how we're 
able to fight off all of these different pathogens   and that is it for today.

i hope that you found 
this video helpful if you want to learn more about   antibodies or our immune systems or even 
our own bodies please subscribe for more!.

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