Qualification > Sciences
ALL CIE BIOLOGY DOUBTS HERE !!!
Deadly_king:
--- Quote from: The Secret on November 12, 2010, 03:26:01 pm ---
So this point in the syllabus just means that we suggest a social, economical and a biological preventive measure to combat these diseases?
Thank you VERY VERY MUCH for your help!! :D
--- End quote ---
Yupz.......you need to use all the theory you learnt on the specific disease to suggest a preventive measure.
Anytime :D
Dania:
1.Please explain why cell membranes are described as having "fluid mosaic" structure.
2. Explain, in terms of protein structure, how it is possible for each type of T cell receptor to
bind specifically to one type of antigen. [Ref: May/June 2002, Paper 2, Question 3 (b)]
Thanks in advance.
ashish:
--- Quote from: Dania on November 12, 2010, 08:33:31 pm ---1.Please explain why cell membranes are described as having "fluid mosaic" structure.
2. Explain, in terms of protein structure, how it is possible for each type of T cell receptor to
bind specifically to one type of antigen. [Ref: May/June 2002, Paper 2, Question 3 (b)]
Thanks in advance.
--- End quote ---
it is fluid because there is lateral diffusion of the fatty acid chains which make it looks like a fluid moving !
it is mosaic because there is protein molecules which has been scattered around the surface!
2)in each T cell receptor there is sequence of amino acids which bind to form a tertiary structure, this means that each T cell receptor has a different variable region. different receptors will bind with complementary antigens .
Deadly_king:
--- Quote from: ashish on November 13, 2010, 03:05:09 am ---it is fluid because there is lateral diffusion of the fatty acid chains which make it looks like a fluid moving !
it is mosaic because there is protein molecules which has been scattered around the surface!
2)in each T cell receptor there is sequence of amino acids which bind to form a tertiary structure, this means that each T cell receptor has a different variable region. different receptors will bind with complementary antigens .
--- End quote ---
Your answers are good but I would just like to add some precision, if you don't mind. ;)
1. Membranes are described as fluid mosaic structure since they consisit of proteins which are scattered among the phospholipid bi-layer giving rise to a mosaic appearance. Moreover the phospholipid within the bi-layer is always on the move rendering it fluid.
2. A T-cell contains a globular protein with a precise conformation showing tertiary structure. The amino acids are arranged in a specific sequence so that there is a variable region that allows only specific antigen with a complementary shape to bind.
Dania:
Thank You, DK!
Oh, I was doing a past paper this morning and there were questions on drug tolerance and caffeine and what not? I don't think that's in the 2010 CIE syllabus, right?
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