Chapter 5 - Cell Recognition And The Immune System Flashcards
What are the two types of white blood cell?
- phagocyte
* lymphocyte
Explain the process of phagocytosis
•1. Phagocyte attracted by a substance/ recognises (foreign) antigen;
- (Pathogen) engulfed/ ingested;
- Enclosed in vacuole/ vesicle/ phagosome; 4. (Vacuole) fuses/joins with lysosome;
- Lysosome contains enzymes;
- Pathogen digested/ molecules hydrolysed;
What is an infection?
An interaction between the pathogen and the defence mechanisms of the body
What is an antigen?
A protein found on the cell surface of pathogens that generate an immune response
What is a pathogen?
A disease-causing microorganism
What is immunity?
When the body is well equipped against invasion from a pathogen so it doesn’t harm the individual
What must lymphocytes do before attacking an invader?
Distinguish between cells that belong to the individual and cells that don’t
What are the four things that the immune system can identify?
- Pathogens
- non-self material
- toxins
- abnormal body cells
Why can the immune system be a problem when receiving organ donations?
The antigens are recognised as non-self, so without immunosuppressants, the immune system would try and attack it
What is a non-specific response?
The response is immediate and the same for all pathogens
What is a specific response?
The response is slower and specific to each pathogen
Two types of non-specific response
- Physical barriers
* phagocytosis
Two types of specific response
- Cell-mediated response
* humoral response
How many types of lymphocyte are there?
10 million
How do lymphocytes recognise cells belonging to the body?
In the womb, lymphocytes are constantly colliding with the body cells of the fetus
Some lymphocytes will have sites that are complementary to these cells
These will either die or be suppressed
The remaining lymphocytes are those that are complementary to non-self material that the fetus hasn’t yet been exposed to
In adults, the same process happens in the bone marrow, producing only lymphocytes that will be able to fight an infection
Process of phagocytosis
A phagocyte recognises foreign antigens on the pathogen
Receptors on the phagocyte bind to the pathogen
They engulf the pathogen, forming a phagosome
Lysosomes fuse with the phagosome
Lysozymes hydrolyse the cell walls of the bacteria, breaking it down
The phagocyte presents the antigens of the pathogen on its surface
What are the two types of lymphocyte?
- B lymphocyte
* T lymohocyte
Where do B lymphocytes mature?
Bone marrow
Where do T lymphocytes mature?
Thymus gland
What type of immunity are B cells associated with?
Humoral
What type of immunity are T cells associated with?
Cell-mediated
What are antigen presenting cells?
Cells that can present foreign antigens on their surface
How do T cells recognise cells to destroy?
They display foreign antigens
How do T cells help to destroy pathogens?
Receptors on the T helper cells are complementary to the antigens presented on the surface of phagocytes
This attachment stimulates the T cell to divide rapidly by mitosis, forming cloned cells
These cells can do one of four things
What are the four things that can happen to T cells after they have been cloned?
- memory cells
- stimulate phagocytes for phagocytosis
- stimulate B cells
- activate cytotoxic T cells
How do cytotoxic T cells kill cells?
They produce a protein called perforin, which creates holes in the cell surface membrane so the cell loses control of what enters and leaves and the cell dies
What is humoral response?
Response to infection using antibodies
What is clonal selection?
Each B cell has a differently shaped active site, which is complementary to only one antigen. When the body is infected with the pathogen with this antigen, the B cell engulfs it and displays the antigen. TH cells bind to this displayed antigen and stimulate the B cell to divide by mitosis
What is the name of the process by which B cells display a foreign antigen on their cell surface?
Endocytosis
When B cells are cloned, what are the two things they can turn into?
- Memory cells
* plasma cells
What type of cell is responsible for the primary defence?
Plasma cells
What do plasma cells do?
They bind to the antigen to form an antibody-antigen complex
How do plasma cells kill pathogens?
Antibodies have two binding sites, meaning they can bind to multiple pathogens at once. This causes them to clump together (agglutination) so phagocytes recognise and destroy them
How do memory cells help to kill pathogens?
They coordinate the secondary response - when you are infected again, they divide rapidly to produce plasma cells (which secrete antibodies) and more memory cells so there is less chance of you becoming ill
Why is the primary immune response so slow?
There aren’t many B cells that can secrete the antibody needed to fight the pathogen
What happens during the primary immune response?
You show signs of the disease - it takes time for the necessary B cells to be made. Then, memory cells are made, which make the secondary response faster
Term applied when antibodies make pathogens clump together
Agglutination
Molecule produced by a B-cell lymphocyte in response to an appropriate antigen
Antibody
A protein which triggers an immune response
Antigen
Site of production of phagocytes and lymphocytes
Bone marrow
These are secreted by T helper cells to activate selected B-Lymphocytes
Cytokines
Place in the bond where bacteria are infested by macrophages
Lympho nodes? (Ask George)
Digestion by antibodies of the bacterial membrane thereby killing the bacterium
Lypis (ask George)
A type of phagocyte
Macrophage
Because this may happen within a species of pathogen we may experience repeated infections from it
Mutation
Large, long lived cells that remove foreign matter from organs and play a crucial role in initiating the specific immune response
Phagocyte
Cells produced by B-lymphocytes which quickly produce specific antibodies
Plasma cells
Name given to the initial response of the immune system when an antigen invades the body
Primary
Name given to response of the immune system which is quick and strong because of the presence of B-memory cells
Secondary
Antigen which is found in the surface of your own cells
Self
The response of the immune system when antigens have penetrated the bodies natural Barrie’s
Specific
Poisonous waste products excreted by bacteria
Toxins
the monomers that form the heavy and light chains
Amino acids
The specificity of an antibody depends on its variable regions. Explain how.
Contains specific sequence of amino acids; Complimentary shape enables attachment to antigen;
What is an antibody?
protein/immunoglobulin; specific to antigen;
idea of ‘fit’/complementary shape;
Explain why this test would detect vCJD, but not other antigens in the urine.
antibodies specific/shape only fits one antigen; other antigens different shape;
would not bind to antibodies;
Describe how antibodies are produced in the body following a viral infection.
- virus contains antigen;
- virus engulfed by phagocyte/macrophage;
- presents antigen to B-cell;
- memory cells/B-cell becomes activated;
- (divides to) form clones;
- by mitosis;
- plasma cells produce antibodies;
- antibodies specific to antigen;
- correct reference to T-cells/ cytokines;
Taking a course of these antibodies from plants to treat a herpes infection would not produce long-term protection against disease. Explain why.
passive;
person is not making own antibodies/antibodies not replaced; memory cells not produced;
Describe how bacteria are destroyed by phagocytes.
- (Phagocyte engulfs) to form vacuole / vesicle / phagosome;
Accept surrounds bacteria with membrane - Lysosome empties contents into vacuole / vesicle / phagosome;
Accept joins / fuses - (Releasing) enzymes that digest / hydrolyse bacteria;
Ignore breakdown / destroy / lytic enzymes
Give two structures a bacterial cell may have that a white blood cell does not have.
- Cell wall;
- Capsule / slime layer; 3. Circular DNA;
Reject “circular chromosome” - Naked DNA / DNA without histones; 5. Flagellum;
- Plasmid;
- Pilus;
- 70s / smaller ribosomes; 9. Mesosome;
What is a pathogen?
Micro)organism that causes disease / harm to body / an immune response;
When a pathogen enters the body it may be destroyed by phagocytosis. Describe how.
- Phagocyte attracted by a substance / recognises (foreign) antigen;
- Antigens (on pathogen) are a specific shape / have specific tertiary / 3D structure;
1/3 Structure alone is insufficient - Antibody fits / binds / is complementary to antigen / antibody-antigen complex forms;
Reject - active site
OR - Antibodies are a specific shape / have specific tertiary / 3D structure;
- accept named substance eg chemical / antigen
- (Pathogen)engulfed / ingested;
- Accept: description
- Enclosed in vacuole / vesicle / phagosome;
- (Vacuole) fuses / joins with lysosome;
- Lysosome contains enzymes;
- Accept named example of enzyme
- Pathogen digested / molecules hydrolysed
Explain why these antibodies are only effective against a specific pathogen
- Antigens (on pathogen) are a specific shape / have specific tertiary / 3D structure;
1/3 Structure alone is insufficient - Antibody fits / binds / is complementary to antigen / antibody-antigen complex forms;
Vaccines protect people against diseases. Explain how.
Vaccines contain antigens / antigens are injected;
Dead pathogens / weakened pathogens;
2. Accept bacteria / viruses etc but not disease
Memory cells made;
On second exposure memory cells produce antibodies / become active / recognise pathogens;
4. Idea of memory cells responding.
Rapidly produce antibodies / produces more antibodies;
5. Production of antibodies must be qualified for mark. Underlined ideas essential.
Antibodies destroy pathogens;
6. Accept bacteria/viruses etc but not disease
Herd effect / fewer people to pass on disease;
What is agglutination?
Red (blood) cells clumping together. (Clotting)
What cause agglutination?
Cell has antigen on its surface where antibodies join to antigens. Antibodies joins cell together.
What are the two types of lymphocytes?
- B lymphocytes
* T lymphocytes
T cells;
•where do they mature?
•what does it act on and how they target?
•type of immune response
- thymus glands
- kill invader cells, foreign cells and cancer cells
- cell-mediated immunity
B cells;
•where do they mature?
•what does it act on and how they target?
•type of immune response
- bone marrow
- foreign material outside cells through the production of antibodies
- humoral immunity
Stages of response of T cells
1) pathogen invade body cells or taken by phagocytes
2) phagocyte places antigen from pathogen in membrane
3) receptors on specific helper T cells for exactly on antigens
4) attachment activated T cell to divide by mitosis and form a clone
5) cloned T cells:
- developed into memory cells
- stimulates phagocyte to ingulf pathogen
- stimulates B cells to divide and discrete antibodies
- activate cytotoxic T cells
What structure are included in an antibody?
- antigen-bonding site (variable region)
- light chain
- heavy chain
- receptor bonding site
Describe monoclonal antibodies and it’s function
- antibodies produced by single clone
* used for targeting specific substances and cells
Describe the direct monoclonal antibody theory
- specific to cancer cells antigens
- attach to receptor on cancer cells
- block chemical signal which stimulates growth
Describe indirect monoclonal antibodies
- attaching radioactive decay to antibody
* can kill the cell
Describe passive immunity
- introduce antibodies from outside
- no direct contact with pathogen and it’s antigen
- no memory cells
Describe active immunity
- stimulates production of own immune system
- memory cells produced
- two types of active immunity
What are the two types of active immunity?
- natural active immunity - produce own antibodies
* artificial active immunity - vaccination (inducing an immune response without suffering from symptoms)
What makes a successive vaccination program?
- economically available
- fee-side effects
- means of production
- administrating the vaccine properly
- herd immunity
What’s hers immunity?
- 95% of the population vaccinated
* so people who don’t get the vaccine are in more contact with those who have than those who are infected
What may vaccinations may not eliminate diseases?
- fail to induce immunity
- develops disease before vaccination can’t take effect
- pathogen may mutate
- variety of pathogen
- pathogen can ‘hide’
- ethical
- medical
- religious
What does HIV stand for?
human immunodeficiency virus
Describe the structure of HIV
- genetic material (RNA) - injects into host cell
- reverse transcriptase - converts RNA to DNA
- matrix
- capsid
- lipid envelope
- attachment protein - to host cell
Describe the replication of HIV
- entry into bloodstream
- binds to CD4 protein found on T helper cell
- capsid fuses with cell-surface where RNA and enzyme of HIV in enters
- reverse transcriptase converts RNA TO DNA
- DNA moved to T helper nucleus
- mRNA created by HIV DNA to make new HIV DNA
- goes through nucleus pore - uses cell protein synthesis
- HIV particles leave T helper cell with cell-surface membrane forms lipid envelope
How does HIV cause the symptoms of AIDS?
HIV tanks T-helper cells. Killing them causes AIDs as without sufficient number of T helper cells, Its cannot stimulate the B cells to produce antibodies and cytoxic T cells to kill pathogen. Memory cell destroyed.
The body becomes suitable for other infections. Secondary disease is normally cause death
How are bacteria and antibiotics linked?
• bacteria cells – constantly doing osmosis – the cells are made out of murein. Antibiotic inhibits enzyme required for synthesis weakening wall – cell bursts
How are viruses and antibiotics linked?
In viruses there are no murein meaning no site for antibiotics to work
Does antibiotics work on viruses?
No
Does antibiotics work on bacterial cells?
Yes
