Cambridge (CIE) AS Biology Your notes
Antibodies & Vaccination
Contents
Antibodies
Making Monoclonal Antibodies
Uses of Monoclonal Antibodies
Types of Immunity
How Vaccines Work
Vaccination to Control Disease
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, Antibodies
Your notes
Antibodies: Structure & Functions
Antibody structure
Antibodies are globular glycoproteins called immunoglobulins
Antibodies have a Y-shaped quaternary structure with two ‘heavy’ polypeptide chains
bonded by disulfide bonds to two ‘light’ polypeptide chains
Antibodies have a constant region and a variable region
The constant regions do not vary within a class of antibodies but do vary between
the classes.
The constant region determines the mechanism used to destroy antigens
The variable region is where the antibody attaches to the antigen to form an
antigen-antibody complex
At the end of the variable region is the antigen-binding site.
Each antigen-binding site is generally composed of 110 to 130 amino acids and
includes the ends of the light and heavy chains
Antigen-binding sites vary greatly, giving the antibody its specificity for
binding to antigens
Antibodies bind to a region of the antigen called the epitope
Antibodies also have a hinge region which gives flexibility to the antibody molecule
This allows the antigen-binding site to be placed at different angles when binding to
antigens
Antibody structure diagram
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, Your notes
Antibodies are Y-shaped molecules with specific antigen binding sites
Antibody function
Antibodies are produced by B lymphocytes
Their role is to bind to specific antigens
Antigens include parts of pathogens and their toxins, pollen, blood cell surface
molecules and the surface proteins found on transplanted tissues
Antibodies can function in several different ways
Antibodies can attach to viruses and to the toxins produced by pathogens to block
them from entering or damaging cells
Antibodies can act as anti-toxins by binding to and neutralising toxins
Antibodies can attach to bacteria, making them readily identifiable to phagocytes;
this is called opsonisation.
Once identified, the phagocyte has receptor proteins for the heavy
polypeptide chains of the antibodies, which enables phagocytosis to occur
Antibodies can attach to the flagella of bacteria, making them less active; this
makes it easier for phagocytes to do phagocytosis
Antibodies act as agglutinins, causing pathogens to clump together in
agglutination
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Antibodies & Vaccination
Contents
Antibodies
Making Monoclonal Antibodies
Uses of Monoclonal Antibodies
Types of Immunity
How Vaccines Work
Vaccination to Control Disease
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 1
, Antibodies
Your notes
Antibodies: Structure & Functions
Antibody structure
Antibodies are globular glycoproteins called immunoglobulins
Antibodies have a Y-shaped quaternary structure with two ‘heavy’ polypeptide chains
bonded by disulfide bonds to two ‘light’ polypeptide chains
Antibodies have a constant region and a variable region
The constant regions do not vary within a class of antibodies but do vary between
the classes.
The constant region determines the mechanism used to destroy antigens
The variable region is where the antibody attaches to the antigen to form an
antigen-antibody complex
At the end of the variable region is the antigen-binding site.
Each antigen-binding site is generally composed of 110 to 130 amino acids and
includes the ends of the light and heavy chains
Antigen-binding sites vary greatly, giving the antibody its specificity for
binding to antigens
Antibodies bind to a region of the antigen called the epitope
Antibodies also have a hinge region which gives flexibility to the antibody molecule
This allows the antigen-binding site to be placed at different angles when binding to
antigens
Antibody structure diagram
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, Your notes
Antibodies are Y-shaped molecules with specific antigen binding sites
Antibody function
Antibodies are produced by B lymphocytes
Their role is to bind to specific antigens
Antigens include parts of pathogens and their toxins, pollen, blood cell surface
molecules and the surface proteins found on transplanted tissues
Antibodies can function in several different ways
Antibodies can attach to viruses and to the toxins produced by pathogens to block
them from entering or damaging cells
Antibodies can act as anti-toxins by binding to and neutralising toxins
Antibodies can attach to bacteria, making them readily identifiable to phagocytes;
this is called opsonisation.
Once identified, the phagocyte has receptor proteins for the heavy
polypeptide chains of the antibodies, which enables phagocytosis to occur
Antibodies can attach to the flagella of bacteria, making them less active; this
makes it easier for phagocytes to do phagocytosis
Antibodies act as agglutinins, causing pathogens to clump together in
agglutination
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 3
