DNA polymerase does not synthesize new DNA strands de novo while RNA Polymerase initiates RNA synthesis de novo without primer

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#Id: 7476

#Unit 4. Cell Communication and Cell Signaling

Antibody Light Chains

Light chain was extremely variable, whereas the sequence of the carboxyl-terminal half could be classified into one of two major sequence types.

κ (kappa) 

λ (lambda) 

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#Id: 7477

#Unit 4. Cell Communication and Cell Signaling

Chromosomal locations of immunoglobulin genes

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#Id: 7478

#Unit 4. Cell Communication and Cell Signaling

IgM antibodies are produced first in a humoral immune response and tend to be of low affinity.

IgM molecules form pentamers that are stabilized by a single J-chain molecule.

This higher avidity of the pentamer compensates for the low affinity

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#Id: 7479

#Unit 4. Cell Communication and Cell Signaling

IgG efficiently opsonizes pathogens for engulfment by phagocytes and activates the complement system. The affinity of the individual antigen binding sites for their antigen is therefore critical for the effectiveness of these antibodies, and most of the B cells expressing these classes have been selected in the germinal centers for their increased affinity for antigen after somatic hyper mutation.

TLS Online TPP Program

#Id: 7480

#Unit 4. Cell Communication and Cell Signaling

IgA is the principal class in secretions, the most important being those from the epithelia lining the intestinal and respiratory tracts.

Dimeric IgA operates mainly on epithelial surfaces.

This monomeric IgA is predominantly of the subclass IgA1; the ratio of IgA1 to IgA2 in the blood is 10:1.

IgA antibodies produced by plasma cells in the gut are dimeric and predominantly of subclass IgA2; the ratio of IgA2 to IgA1 in the gut is 3:2.

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#Id: 7481

#Unit 4. Cell Communication and Cell Signaling

IgE 

Present only at very low levels in blood or extracellular fluid but is bound avidly by receptors on mast cells.Antigen binding to this cell-associated IgE triggers mast cells to release powerful chemical mediators that induce reactions such as coughing, sneezing, and vomiting.