Transcript Antibody Structure and Function

Antibody Structure and Function
Each antibody is produced by
lymphocytes (specialised white cells) as
a result of exposure to specific
chemical substances (mainly proteins
and carbohydrates) called antigens,
usually on the outside of an invading
organism. They are able to react to
form an antigen-antibody complex.
At the molecular level, antibodies
are known to be shaped like the
letter Y, with a reactive site at the
tip of each branch, so that
antibodies can become attached to
antigens on the basis of their
molecular shape, rather like an
enzyme and substrate. This can
cause the infecting microorganisms to stick together, and
neutralises them until they are
taken away and dealt with by other
white cells.
Effector mechanisms
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© Boardworks Ltd 2008
Antibody structure
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© Boardworks Ltd 2008
Antibody Structure
The specificity of the
antibody depends on its
variable regions
Antigen
Variable
regions (red)
The constant
regions are the
same for all
antibodies
Light chain
Hinge region
Disulphide bridges
Heavy chain
Constant regions
(blue)
Each antibody has a different shaped variable region (Due different amino acid
sequences) that is complementary to one specific antigen
Antigen
binding
site
Antigen
binding
site
The structure
of an antibody
All antibodies are proteins. This means that they are made up of a long
chain of amino-acids which are arranged into a complex structure.
How do Antibodies Work?
Using the templates sheet, make a
poster explaining how antibodies
can fight infection
Key Terms:
 Agglutination
Neutralisation
Agglutination
 Antibodies can cause
microbes to stick
together
 This makes it
easier for
phagocytes
to engulf
them
Neutralisation
 Some pathogens make us ill by producing toxins
 Some antibodies work by
neutralising these
toxins
 Viruses have proteins on their surface which recognise
and bind to receptors on the surface of the host cell
 This is how many viruses enter their host cell
 Antibodies can bind to viruses
and stop them attaching to
their host cells
PATHOGENS
ANTIBODIES
TOXINS
Questions
1. In what ways are antibodies similar to enzymes?
2. What is formed between an antibody and a pathogen?
3. Complete the key words for this lesson:
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A________-__________ ________
T_______ s_________
P__________ c________
V__________ r__________
Ag_________________
N____________________
A__________ a_________
D__________ b________
Q___________ s________
Add any other key words that have been missed.