Antibody Structure and Function. Each antibody is produced by lymphocytes (specialised white cells) as a result of exposure to specific chemical substances.

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 micro-organisms to stick together, and neutralises them until they are taken away and dealt with by other white cells.

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Effector mechanisms

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Antibody structure

Hinge region

Constant regions(blue)

Heavy chain

Light chain

Variable regions (red)

Antibody Structure

Antigen

Disulphide bridges

The constant regions are the

same for all antibodies

The specificity of the antibody depends on its

variable regions

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

TOXINSANTIBODIES

PATHOGENS

Questions1. 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:

– A________-__________ ________– T_______ s_________– P__________ c________– V__________ r__________– Ag_________________– N____________________– A__________ a_________– D__________ b________– Q___________ s________– Add any other key words that have been missed.