the difference between complement activation by antigen-IgM complexes and antigen-IgG complexes accounts for thae fact that a pentameric IgM bound to an antigen on the surface of the target cell takes up the "staple"conformation. in this conformation 3 binding sites for C1q are exposed.
In contrast, an IgG molecule has one C1q binding site in the CH2 domain of Fc region. A strong C1q binding is achieved when 2 IgG molecules are close i.e. within 30-40nm of each other on the surface of the target site,in turn providing two attachment sites for C1q.
due to this difference a single IgM molecule is responsible to activate the complement system while nearly 1000 molecules of IgG is required to do so as it then ensures whether any 2 IgG molecule is close enough on the surface of the cell to initiate C1q binding.
O What is the difference between complement activation by antigen-IgM complexes and antigen- IgG complexes?
QUESTION 5 Which of the following is CORRECT? Only IgG and IgM can result in complement fixation or activation. The initial response to an antigen produces more antibodies than the second or subsequent exposures. The initial response to an antigen is more rapid than the second or subsequent exposures. Only IgG can cross the placenta. IgM and IgE are both pentamers. They can bind 10 antigens. The antibodies all have different variable regions by same constant regions QUESTION 6 Select...
Describe the process of B cell activation starting with antigen binding to IgM.
What are the relative percent concentrations of IgG, IgM, IgE, IgA, IgD in the body?
In order to begin the complement activation cascade in response to an antigen like LPS from bacteria, the following is needed (assume LPS does NOT contain repeating epitopes but instead has a specific epitope): Select one: O a. The CCR5 receptor, on the epithelial cell, which will bind to the T cell receptor complex on the T cell O b. The T cell receptor complex on the T cell, which will bind to the B cell receptor on the B...
1. In general, antibodies can defend against pathogens in any of six ways. However, IgM and IgA can only use a few of these methods. Which of the following could be used by IgM or IgA to inactivate pathogens? A. Agglutination B. Opsonization C. Complement activation D. NK cell activation E. TH cell activation 5. A B cell recognizes an antigen, but there is no Th cell that also recognizes the antigen. What will happen? A. The B cell will...
29.) An immunoassay was performed in the following way: Antigen is bound to a solid support. Patient serum is added and patient antibodies bind to the antigen. The well is washed and enzyme-labeled anti-immunoglobulin antibodies are added. The well is washed and enzyme substrate is added and enzyme activity is determined. Which immunoassay is described? A. latex agglutination B. competitive C. ELISA D. homogeneous 30.) Erythema migrans (EM) is the caused by tick bite: A. itchy rash B. red bull's-eye...
which is correct answer
QUESTION 38 Which of the following is associated with anaphylaxis? O Activation of Complement Activation of Tc cells O Buildup of IgE on mast cells Large amounts of IgG
5. Explain why direct antigen activation of CTLs and B cells is more important than APC-initiated activa- tion in subsequent encounters with a microbe. Why is the APC-initiated pathway needed at all? 6. There are many interactions between the innate and adaptive defense systems. List as many of them as you can and explain how they work. Why are these interactions important? Are all of them beneficial? 7. What are the two ways that polysaccharides, DNA, and lipid antigens can...
Where does the activation of complement system take place? What molecule is responsible for the activation of complement system? How is the bacterial cell going to be destroyed eventually?
B cell activation requires (select ALL that apply): O T cytotoxic cells O Tcell receptor (TCR) binding to antigen displayed in MHC-|| O antigen binding to antibody on B cell surface T cell receptor (TCR) binding to antigen displayed in MHC-I Question 3 1 pts Which statement(s) about C proteins in the complement system is true (select ALL that apply): Cproteins are always active as they circulate through the body All of the C proteins are equally important for all...