Antibodies: Structure, Functions, and Applications
Antibodies
Saturday, 07 September 2024
Learners should be able to demonstrate and apply their
knowledge and understanding of:
•
the structure and general functions of antibodies
To include the general structure of an antibody
molecule.
•
an outline of the action of opsonins, agglutinins and
anti-toxins
Starter: What came first?
The T cell
The B cell
The T killer cell
Task 1
Label the different regions of an antibody
using the labels provided.
Support: Text books
Extra challenges:
1)
Explain the importance of the variable
regions.
2)
What is an antigen-antibody complex?
LO: Describe the structure of antibodies.
Hinge
region
Allows flexibility
Constant regions
(blue)
Heavy chain
Light chain
Variable
regions
(red)
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Antigen
The constant
regions are the
same for all
antibodies and
this is how
phagocytes can
recognise them
The
specificity
of the
antibody depends on its
variable regions
Each antibody has a different
shaped variable region of 110
amino acids
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2 variable regions
allow the antibody
to bind to 2 of the
same antigens
Task: How do antibodies work?
Using the templates sheet, make a
poster explaining how antibodies
can fight infection.
You should include:
-
Neutralisation
-
Agglutination
-
Opsonisation
Support: Text books, peers
Extra challenge: How do
antibodies prevent viruses
entering a cell?
LO: Compare the different
modes of action of
antibodies.
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Antibodies act as
agglutinins which can cause
microbes to stick together
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This makes it
easier for
phagocytes to
engulf them
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Some pathogens make us ill by producing
toxins
Some antibodies work by
producing anti-toxins which
can neutralise them by
blocking their action
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The binding of an antibody such as IGG or IgM to the
surface of a pathogen can tag the pathogen which helps the
phagocyte identify it and then engulf it
Some opsonins can make the
pathogen walls leaky so that
they swell up and burst
•
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
forming an antigen antibody
complex which stops them
attaching to their host cells
11
Primary – establishes immunological
memory
Primary and secondary responses
Annotate your graph of the primary and secondary responses
by adding the following labels:
Clonal selection
Clonal expansion (more plasma cells and Killer T etc)
Mitosis
Development of memory cells
Questions:
1)
Compare the primary and secondary responses in terms of
time taken, decline of antibodies and antibodies produced.
2)
Memory cells are produced in the primary response, how
else could these be produced without the person being
infected?
Extra challenge: What causes the secondary response to occur
more rapidly?
13
Antibody Concentration – Primary and Secondary Response
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Secondary Response
After the primary response, Ab’s do not stay in blood – the
level declines
If the body is infected by the same Ag a second time Ab’s must be made again
Re-infection causes
much more rapid
and a
stronger
immune response – concentration of Ab’s rises
sooner- reaches a higher concentration – more plasma cells than in 1o response – more cells to
respond to Ag; less time to produce same number of plasma cells –hence, a greater [Ab] compared to
1o response; increased affinity of Ab for Ag.
This is due to the presence of
memory cells
(made during the primary response) – no need for antigen
presentation and clonal selection
Long-lived
; basis of vaccination
Autoimmune diseases
•
The immune system stops recognising some cells as
‘self’ to will attack them causing inflammation and
destruction of healthy tissues
•
Three of the most common
–
Type 1 diabetes damages the
β
cells in the pancreas
–
Rheumatoid arthritis attacks joints causing scarring and
swelling
–
Lupus which can damage many organs such as kidneys and
liver and skin often causing a persistent facial rash
•
There are no cures for these diseases but can be
managed with other medications such as insulin
injections or immunosuppresants
Plenary: True or False?
1)
Antibodies have a variable region specific to a
pathogens antigens.
2)
Antibodies contain a sulphide bridge.
3)
A antigen-antibody complex is formed when an
antibody binds to a pathogen’s antigens.
4)
Agglutination makes it easier for phagocytes to
engulf pathogens.
5)
Neutralisation only occurs with viruses.
6)
Opsonisation causes phagocytes to swell and burst.
7)
Antibodies can stop viruses entering host cells.
8)
The primary immune response produces memory cells.
9)
The secondary immune response is caused by
vaccination.
10)
The secondary immune response is quicker.
Resources
TOXINS
ANTIBODIES
PATHOGENS
Explore the structure and functions of antibodies, including how they bind to antigens, act as opsonins, agglutinins, and anti-toxins. Learn about the specificity of antibodies, their variable regions, and their role in neutralizing pathogens and viruses. Gain insights into how antibodies help the immune system recognize and combat different threats.
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Presentation Transcript
Antibodies Saturday, 07 September 2024 Learners should be able to demonstrate and apply their knowledge and understanding of: the structure and general functions of antibodies To include the general structure of an antibody molecule. an outline of the action of opsonins, agglutinins and anti-toxins
Starter: What came first? The T cell The B cell The T killer cell
http://www.frontiers-in-genetics.org/en/pictures/antibody_2.jpghttp://www.frontiers-in-genetics.org/en/pictures/antibody_2.jpg
Each antibody has a different shaped variable region of 110 amino acids Antibody Structure 2 variable regions allow the antibody to bind to 2 of the same antigens The specificity of the antibody depends on its variable regions Antigen Variable regions (red) Light chain The constant regions are the same for all antibodies and this is how phagocytes can recognise them Hinge region Allows flexibility Disulphide bridges hold the heavy and light chains together Heavy chain Constant regions (blue) Each antibody is complementary to one specific antigen which it can bind to forming an antigen-antibody complex
Agglutination Antibodies act as agglutinins which 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 producing anti-toxins which can neutralise them by blocking their action
Opsonisation The binding of an antibody such as IGG or IgM to the surface of a pathogen can tag the pathogen which helps the phagocyte identify it and then engulf it Some opsonins can make the pathogen walls leaky so that they swell up and burst
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 forming an antigen antibody complex which stops them attaching to their host cells
Primary establishes immunological memory 11
Primary and secondary responses Annotate your graph of the primary and secondary responses by adding the following labels: Clonal selection Clonal expansion (more plasma cells and Killer T etc) Mitosis Development of memory cells Questions: 1) Compare the primary and secondary responses in terms of time taken, decline of antibodies and antibodies produced. 2) Memory cells are produced in the primary response, how else could these be produced without the person being infected? Extra challenge: What causes the secondary response to occur more rapidly?
Antibody Concentration Primary and Secondary Response Primary Response 1. Infection (Ag) 2. Lag phase 3 Antibodies produced 4 Antibody level rises to combat infection 5 Ag dealt with 6 Ab level declines short lived Secondary Response After the primary response, Ab s do not stay in blood the level declines If the body is infected by the same Ag a second time Ab s must be made again Re-infection causes much more rapid and a stronger immune response concentration of Ab s rises sooner- reaches a higher concentration more plasma cells than in 1o response more cells to respond to Ag; less time to produce same number of plasma cells hence, a greater [Ab] compared to 1o response; increased affinity of Ab for Ag. This is due to the presence of memory cells (made during the primary response) no need for antigen presentation and clonal selection 13 Long-lived; basis of vaccination
Autoimmune diseases The immune system stops recognising some cells as self to will attack them causing inflammation and destruction of healthy tissues Three of the most common Type 1 diabetes damages the cells in the pancreas Rheumatoid arthritis attacks joints causing scarring and swelling Lupus which can damage many organs such as kidneys and liver and skin often causing a persistent facial rash There are no cures for these diseases but can be managed with other medications such as insulin injections or immunosuppresants
Plenary: True or False? 1) Antibodies have a variable region specific to a pathogens antigens. 2) Antibodies contain a sulphide bridge. 3) A antigen-antibody complex is formed when an antibody binds to a pathogen s antigens. 4) Agglutination makes it easier for phagocytes to engulf pathogens. 5) Neutralisation only occurs with viruses. 6) Opsonisation causes phagocytes to swell and burst. 7) Antibodies can stop viruses entering host cells. 8) The primary immune response produces memory cells. 9) The secondary immune response is caused by vaccination. 10) The secondary immune response is quicker.
PATHOGENS ANTIBODIES TOXINS
