Download Week 11 - Immune Responses - NSW and VIC Biology for Year

11.1
Week 11
Immune Responses
Area of Study 2
Detecting and Responding
Key knowledge
 Specific immune response: T-cell lymphocytes and cell-mediated
response; B-cell lymphocytes and humoral response, antigen,
antibodies; memory cells.
Key skills
 Investigate and inquire scientifically
 Apply biological understandings
 Communicate biological information and understanding.
Tasks this week relate to Outcome 2.
 Describe and explain coordination and regulation of an organism’s
immune responses to antigens at the molecular level.
Relevant websites – See online biology course environment. Go to the
Links section.
Glossary terms for Week 11 can be found here:
http://quizlet.com/_sfd5
Introduction
Read carefully through this Week’s work before completing the tasks.
The Objectives
By the end of this week you should be able to:
 Define and distinguish in finer detail, specific and adaptive defences.
Please note: Last week (Week 10) you covered features of the nonspecific immune defences. This week you will focus on the specific
immune defences, in more detail.
11.2
The clonal-selection theory of antibody production
Courtesy of Nature of Biology by Jacaranda
When an antigen enters the body it probably passes many B cells before it
meets one with immunoglobulin with which it can combine. In effect, the
antigen ‘selects’ the B cell that will lead to its death. The B cell selected
by the antigen reproduces rapidly to give rise to a number of identical
cells. Each of these cells also reproduces rapidly to produce a large clone
of cells. This is called clonal expansion. Cells cloned in this way will all
have exactly the same genetic material and the same immunoglobulins.
Most of these cells then differentiate into plasma cells and produce the
same kind of antibody (see figure 8.15).
An Australian, Sir Macfarlane Burnet, first proposed the clonal selection
theory in 1955.
There is a delay in this type of immune response because clonal expansion
is necessary before sufficiently large amounts of antibodies can be made.
This means that, if the infecting bacteria are able to reproduce to form
relatively large numbers, a person may become quite ill before antibodies
are produced that can react with the bacteria.
Some of the B cells produced differentiate into other cells called Bmemory cells. B-memory cells also have the same antibody–antigen
specificity as the parent B cell. Plasma cells survive for only a few days
but memory cells can survive for several years and, in some cases, for life.
If a second infection of the bacterium occurs, the B-memory cells react
faster and more vigorously than the initial B-cell reaction to the first
infection. There is not usually a noticeable effect from a second infection
by the same antigen because the body reacts very quickly to eliminate the
11.3
‘non-self material’. The person is said to be immune to the particular
disease. When recovery from infection is complete, fewer plasma cells
and antibodies are produced. Because most of the cells produced by clonal
expansion are no longer required after recovery from the infection, they
die by apoptosis (important to note this!).
The following text is courtesy of Heinemann Biology Two 4 th Edition
Antigens and antibodies
The highly efficient defence provided by the immune system is based on its two
distinguishing features: the ability to respond specifically against a particular foreign
substance (an antigen) and the ability to ‘remember’ a previous encounter with a foreign
substance and react very rapidly if it is encountered again.
Antigens
By definition, antigens are molecules, usually proteins or carbohydrates, that are able to
bind to antibodies (or T cell receptors) and stimulate production of antibodies. T cell
receptors are antibody-like molecules located on the surface of T cells. Antigens are found
on the surface of cells and the outer coats of viruses, and they may be released by bacteria
as toxins. Part of the antigen molecule stimulates lymphocytes to begin the immune
response.
Antibodies
Most antibodies are large globular glycoproteins, called immunoglobulins (lg), produced
by lymphocytes and released into the blood plasma. They are highly selective and react
with specific antigen molecules (in a similar way to the interaction between enzyme and
substrate). Antibody molecules are basically Y-shaped, with two identical arms that bind
two antigen molecules and a stem that recruits complement activation. They may act
singly (monomers), in pairs (dimers) or in groups of five (pentamers). See the following
table of the five main classes of antibody molecules that have been identified.
Courtesy Heinemann Biology Two 4th Edition.
11.4
Read through pages 182 to 190 of your text book and complete the tasks or
questions that follow. Use your own A4 paper or send work as MSWord
documents attached to an email
SEND…
Questions
1. How does the innate immune response differ from the adaptive
immune response?
2. Why is it that over 10 million different types of antibodies can be
produced by our body?
3. Plasma B lymphocytes possess an extensive rough endoplasmic
reticulum, many Golgi apparatuses and many mitochondria. Explain
why. You may need to refer to the glossary on page 388 for some of
these terms.
4. Describe what is meant by ‘clonal selection’ using B cells as an
example.
5. a. What type of compound is an antibody?
b. How does an antibody differ from an antigen?
c. List three ways that antibodies can act to fight off a pathogen.
6. Reorganise the boxes in Figure 11.1 below into a flow chart that could
act as a battle plan for defence against an infection caused by
Mycobacterium tuberculosis. You may present your flow chart in a
branching form. It does not have to be a straight line.
Figure 11.1
Complement proteins
cause lysis of bacterial
cells
Phagocytes engulf
bacterium destroyed by
antibodies
Histamines secreted by
mast cells cause
inflammation
Antigens from bacterium
bind with antibody on
immature B cell
T-helper cell secretes
lymphokines to help B
cells divide
B cell divides to produce
many plasma and
memory cells
Plasma cells produce
many antibodies
Antibodies bind with
antigens on bacterium
Mucous membrane
lining trachea traps
bacteria
Memory cells migrate to
lymph nodes to be ready
to fight a second
infection quickly
Cilia lining trachea
move mucus up and out
of the body
11.5
7. Liver, heart and kidney transplants are now fairly common procedures
in many hospitals. Recipients of these transplants, however, face the
problem of rejection of these organs.
a. Explain why the immune system rejects these organs.
b. Organ recipients are usually treated with immunosuppressant
drugs. What is the function of these drugs?
c. What might be a negative effect of these drugs on the health of the
patient?
8. It is advised that all children get immunised against the common
childhood diseases, such as measles and polio. Figure 11.2 (on the
next page) shows the effect of immunisation on antibody production.
a. Explain the body’s primary response.
b. Explain the trend shown following the second dose of antigen.
Figure 11.2 The effect of immunisation on antibody production
9. a.
b.
c.
d.
Where are T cells originally formed and where do they mature?
What type of response is produced by T cells?
Describe the function of T-helper (TH) and cytotoxic T cells (TC).
Explain the consequences of being born without T cells.
10. The life cycle of Trypanosoma brucei is described in Chapter 5. The
parasite has a number of intermediate stages in both the tsetse fly and
the human hosts. Explain, in terms of detection and response by the
human immune system, why this is an advantage to the parasite.
11.6
11. Australia has many venomous snakes. One species, commonly called the death
adder (Acanthophis antarticus), has one of the most dangerous bites in the world.
The active component of the venom is an alpha-neutrotoxin that binds to the
receptor sites for acetylcholine. Paralysis of muscles results and death can occur
when the muscles of the diaphragm become paralysed and breathing is prevented.
a. What type of substance is acetylcholine?
b. What is the function of acetylcholine?
c. Explain how the alpha-neurotoxin prevents the acetylcholine from working.
d. Fortunately, there is an antivenom injection available to people who have been
bitten by a death adder. If the antivenom is injected quickly enough it prevents
the paralysis. The antivenom is prepared by injecting tiny amounts of snake
venom into horses over a long period of time. The amounts of venom injected are
so small that the horses are unaffected; however, there is a response by the
horses’ immune system. What substances would the horse produce in order to
counteract the snake venom in its body?
e. What cells in the horse would be responsible for the formation of this substance?
f. Explain why small amounts of venom are injected into the horse over a long
period of time.
g. Outline the steps involved in the formation of these substances.
h. After 10-12 months blood is extracted from the horse and the plasma can be
injected into snake-bite victims. What term is given to the use of horse plasma as
a treatment for snakebite?
i. How is this effective in treating the snake-bite victim?
12. Use the visual summary provided below.
Write short phrases or words that could replace the lines that link the boxes – See the
example I’ve provided below.
Example: responses to entry of foreign material are important in identifying
self.
11.7
Key Summary Points









Specific defence is provided by an elaborate immune system.
Vertebrate immune responses are characterised by specificity and
memory.
Immune responses involve lymphocytes (a particular group of white
blood cells formed in the bone marrow and spleen.)
Immune responses include both humoral (‘blood-borne’) and cellmediated mechanisms. In humoral immunity antibodies are released
by B cells; in cell-mediated immunity, active destruction is carried out
by T cells.
Antigens are molecules able to bind to antibodies or T cell receptors.
They stimulate lymphocytes to begin the immune response.
Antibodies are specific proteins produced by lymphocytes that are
able to react with particular antigen molecules.
T cells are responsible for cell-mediated immune responses. Tc cells
act against virus-infected cells, cancer cells and transplanted tissue. TH
cells assist B cells and TC cells.
B cells are lymphocytes that produce large quantities of antibodies
when stimulated by particular antigens. This is the humoral immune
response.
The clonal selection theory explains how, using only a moderate
amount of DNA, the immune system responds quickly to an almost
unlimited array of foreign antigens.
Challenging Activity: Mnemonic Activity
Choose one or more terms from the list given on page 199 of your
textbook and create a memory aid to help you remember the definition
of that term. You may use drawings, poetry, song, sound, whatever
works for you! Share your ‘mnemonic’ (memory aid) with the other
students of your class via the chat room. Feel free to discuss your ideas
with me. Use the glossary found on page 388 for definitions of terms.
Log on to the www.decvonline.vic.edu.au check out the back of your
DECV book for your login details if you have forgotten.
Click on the link to the Unit 3 Biology course.
Click on the button “Discussion Room”
Place your Mnemonic as a comment to the Discussion post titled
Mnemonics Week 11.
Make sure you check out the other Mnemonics left by your classmates
and leave them a comment.
11.8
Challenging Activity: Personal Reflection
Log on to the VCE Biology Course. Place your Personal Reflection in the
Biology Blog as outlined on 0.7 in the introduction of this book.
Exam Practice Exercise
Past Exam Questions
Each week you will get at least one question which relates to the weeks
work, which comes from a past VCE exam paper.
The purpose of this task is to familiarize yourself with the type of
questions you will encounter during the exam and the timing you should
devote to each.
Timing
You should allow 1 minute and ten seconds per mark assigned to the
question.
Question 1 (Q20, 2000)
Non-specific immunity in mammals includes
A. the action of lysozymes in tears and saliva.
B. the production of antibodies after infection.
C. the production of memory cells.
D. the action of T helper cells.
1 marks
Question 2 (Q7, 2001)
A bacterium with two different proteins on its surface can be represented as
follows:
Antibodies produced against this bacterium include:
11.9
1 marks
Question 3 (Q8, 2001)
Specific immunity in a person includes:
A. ingestion of bacteria by phagocytes.
B. involvement of helper T cells and B cells.
C. development of inflammation around a cut.
D. production of lysozymes in tears.
1 marks
Question 4 (Q22, 2002)
In humans, non-specific immunity includes:
A. production of antibodies by plasma cells.
B. different responses for different bacteria.
C. destruction of bacteria by enzymes in saliva.
D. presentation of material to a T cell by a phagocyte.
1 marks
(Total 4 marks)
Checklist
This week you should have sent this work to me.
Please tick the items you have sent, and keep this as your record:

Responses to Questions 1-12

At least one mnemonic of a biological term left online

Your personal Reflection left online
Don’t forget to drink plenty of water!
11.10
Feedback
What if anything needs to be improved, corrected, cleared up or presented
better from the materials presented in this week? Your honesty is
appreciated. Write your comments on the back of the cover sheet.
Answers to Past Exam Questions
Question 1 Non-specific immunity in mammals includes:
A. The action of lysozymes in tears and saliva. All the other alternatives
mention elements of specific immunity.
Question 2 Antibodies produced against this bacterium include:
C. (Alternatives B and D can be eliminated because their antigen binding
sites do not fit either of the proteins on the surface of the bacterium.
Alternative A is incorrect as it shows an antibody with 2 different antigenbinding sites. One antibody has 2 identical antigen-binding sites.
Question 3 Specific immunity in a person includes:
B. Involvement of helper T cells and B cells. All other alternatives are
examples of non-specific immunity.
Question 4 In humans, non-specific immunity includes:
C. Destruction of bacteria by enzymes in saliva. A, B and D are all part
of specific immunity.
END OF WEEK 11
11.11
315 Clarendon Street, Thornbury 3071
Telephone (03) 8480 0000
FAX (03) 9416 8371 (Despatch)
Toll free (1800) 133 511
Fix your student barcode
label over this space.
SCHOOL NO.
64811
[64811]
STUDENT NUMBER ___________________
SCHOOL NAME _______________________
STUDENT NAME ______________________
SUBJECT
Biology Unit 3
YEAR/LEVEL
TEACHER
12
WEEK
11
________________________
[ZX]
PLEASE ATTACH WORK TO BE SENT.
NOTE: Please write your number on each page of your work which is attached to this page.
SEND
Please check that you have attached:

Response to Questions 1-12

At least one mnemonic of a biological term left online

Your Personal Reflection for week 11
If you have not included any of these items, please explain why not.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Use the space on the back of this sheet if you have any questions you would
like to ask, or problems with your work that you would like to share with
your teacher.
11.12
YOUR QUESTIONS AND COMMENTS
Please provide the following information:
Were you able to complete the tasks in the time frame allocated? ____________________
Roughly how long did it take for you to complete this week of work? _____________
Use this space for any queries or comments you have, (or maybe errors you’ve found).
DISTANCE EDUCATION CENTRE TEACHER’S COMMENTS
DISTANCE EDUCATION CENTRE TEACHER