|Why are antibodies known as immunoglobulin? ||Because they are globular proteins.|
|Name the classes of antibody? ||IgG, IgM, IgA, IgD, IgE.|
|Describe the the polypeptide chains of an antibody. ||Two identical heavy chains and two identical heavy chains.|
|What does the type of heavy chain depend on? ||The antibody class.|
|Name the types of light chain, ||Lambda and Kappa.|
|How are the chains held together? ||Via disulhpide bonds.|
|How do individual chains exist in an antibody? ||Coiled around each other.|
|What molecule stabilises the antibody structure? ||Small carbohydrate molecules.|
|How many domains are light chains divided into? ||1 variable chain and 1 constant chain.|
|How many domains are heavy chains divided into? ||1 variable chain and 3 constant chains.|
|How long is each domain? ||Roughly 110 amino acids long.|
|How are domains stabilised? ||By internal disulphide bonds.|
|Describe the variable domain. ||Located at the N terminus of the polypeptide, it forms the the ends of the arms of the antibody and is known as the Fab potion. This portion serves as the antigen binding site.|
|Describe the constant domains. ||Located at the C terminus of the polypeptide chain, the heavy chain constant domains form the bottom part of the Y structure of the antibody. Known as the Fc region, it is the responsible for the biological activity of the antibody.|
|What can the constant domain on the heavy chain bind to? ||Cells and compliment system proteins.|
|What forms the antigen binding site? ||3 hyper-variable domains from the heavy chain and 3 hyper-variable domains from the light chain.|
|How does the antigen binding site achieve diversity? ||Antibody genes spliced together from different chromosomes.
Large choice of genes for same domain.
Variations during splicing.
A high rate of somatic mutation.|
|What chromosome codes for Lambda light chain synthesis and how is it carried out? ||Chromosome 22, with multiple genes for both constant and variable domains. Variable and constant domains are coded for by separate parts of the chromosome, There are multiple genes for the joining chains and the choice of each gene is random.|
|How does the synthesis of the Lambda light chain affect its production? ||It causes there to be a vast number of different Lambda light chains.|
|What chromosome codes for Kappa light chains and how is it carried out? ||Chromosome 2, with multiple genes for the variable and joining domains but with only one constant domain gene, gene selection is random for each domain.|
|How does the synthesis of the Kappa light chain affect its production? ||It causes there to be a vast number of different Kappa light chains.|
|Name the type of heavy chain that exists in an antibody. ||Gamma heavy chain.|
|What chromosome codes for the Gamma heavy chain and how is it carried out? ||Chromosome 14, with multiple genes coding for variable, constant, and joining chains.|
|Where are the hyper-variable domains, also known as CDR, coded for on light chains? ||Lambda and Kappa light chain CDR 1and CDR 2 are coded for on the variable domain genes of their respective chromosomes. With CDR 3 also containing coding from the joining domain.|
|Where are the hyper-variable domains coded for on heavy chains? ||Gamma heavy chain CDR 1 and CDR 2 are coded for on the variable domain genes of its chromosome, with CDR 3 being coded for on variable domain genes, joining domain genes, and heavy chain unique diversity genes, also found on its respective chromosome.|
|What is somatic mutation? ||The programmed process of mutation that affect the variable region.|
|What happens during somatic mutation? ||B lymphocytes undergo a large number of cell divisions, leading to increased diversity.
Most mutations tend to be in variable genes, within the hyper-variable regions.|
|What is the outcome of somatic mutation? ||Increased to decreased affinity to an antigen.|