Cells and the Immune System- Topic 2C Flashcards
Give 3 examples of a pathogen
Bacteria, viruses and fungi
What is an antigen?
A foreign molecule that can generate an immune response when detected by the body.
Where can antigens usually be found?
On the surface of cells.
What 3 things do antigens identify?
Pathogens, abnormal body cells (cancerous cells), toxins
What are the 4 main stages in the immune response?
Phagocytes engulf pathogens
Phagocytes activate T-cells
T-cells Activate B-cells, which divide into plasma cells
Plasma cells make more antibodies to a specific antigen.
What is a phagocyte?
A type of white blood cell that carries out phagocytosis. Found in the blood and in tissues. They are the first cells to respond
What is a phagosome?
the phagocytic vacuole
What is an antibody?
A protein that binds to a specific antigen to form antigen-antibody complexes
What are monoclonal antibodies?
Antibodies SPECIFIC to the antigen.
The immune response can be split into two. What are these responses?
Cellular- T-cells and other immune system cells
Humoral- B cells, clonal selection and production of monoclonal antibodies
What are both types of immune response needed to do?
Remove a pathogen from the body. Responses interact with each other.
What is the primary response?
When an antigen enters the body for the first time and activates the immune system.
At first the primary response is …… because there ….. …… …. that can make the antibody needed to bind to it.
At first the primary response is slow because there aren’t many B-cells that make the antibody needed to bind to it.
What does the humoral response involve?
B-cells, clonal selection and monoclonal antibodies.
Describe the function of antibodies
Bind pathogens together
Allowing phagocytes to engulf many pathogens at once.
What is agglutination?
When an antibody binds 2 pathogens (as it has 2 binding sites) at the same time so that pathogens become clumped together.
What is phagocytosis?
Engulfment of pathogens
Vaccines can protect ……. and …….. against disease
Vaccines can protect individuals and populations against disease.
What do vaccines contain?
Antigens that cause the body to produce memory cells against a particular pathogen without the pathogen causing disease.
Vaccines help you become …… so you don’t get any ………
Vaccines help you become immune so you don’t get any symptoms.
What is herd immunity?
More individuals being vaccinated reduces occurrence of the disease so those not vaccinated are also less likely to catch it.
Vaccines always contain antigens which can be in 2 forms. Name them.
They may be free
Attached to a dead/ weakened pathogen (Attenuated
Name 2 ways that vaccines can be taken and give a disadvantage of one of these
Injected or taken orally.
If take orally enzymes could break it down in the gut or molecules are too large to be absorbed into the blood.
Why may a booster vaccine be given?
To make sure that memory cells are produced.
Explain why you may be infected a second time and get ill again?
Some pathogens change their surface antigens which aren’t recognised by the memory cells.
Give 2 examples of pathogens that show antigenic variation
HIV and Influenza virus.
What is active immunity?
When your immune system makes its own antibodies after being stimulated by an antigen.
What is passive immunity?
Immunity from being given antibodies made by a different organism.
Explain the 2 types of active immunity
Artificial- immune after vaccination
Natural- immune after catching the disease
Explain the 2 types of passive immunity
Natural- when a baby becomes immune from receiving the antibodies from its mother through placenta and breast milk.
Artificial- Becoming immune after being injected with antibodies from someone else.
What is a macrophage
A type of phagocyte
What is another name for cytotoxic T cells?
Killer T-cells
What is a lysosome?
An organelle that contains enzymes called lysozymes
What is meant, when the phagocyte “presents” the pathogens antigens?
It sticks the antigens on its surface to activate other immune system cells.
What, on a T cell, will bind to the complimentary antigens presented to it?
Receptor proteins on its surface
What do lysozymes do?
Break down the pathogen
What is clonal selection?
Activation of B-cells which divide into plasma cells
What does the specificity of an antibody depend on?
It’s variable regions, which form antigen binding sites
All antibodies have the the same…
Constant regions.
How is a phagosome formed?
The cytoplasm of the phagocyte moves around the pathogen, engulfing it.
What is the final stage of the immune response?
Antibodies bind to the antigens and inhibit the functioning of the foreign cells.
Why are antibodies referred to as monoclonal?
The antibodies are produced from the same B cell/ plasma cell
Give 2 ways in which a pathogen may cause disease when it’s entered the body.
infection–> produces toxins
damages/kills cells
Tests using monoclonal antibodies allow vets to identify disease while they’re still on a farm. Explain advantages of this. (3)
Reduces spread of disease
Isolation of infected animals
Treatment of carries/disease.
Name differences between active and passive immunity:
Active involves memory cells (passive doesn’t)
Active involves production of antibody by plasma cells
Passive involves antibody introduced into body from outside
Active= long term
Passive= short term
Active can take time/passive fast acting
What do we call an antibody bound to an antigen?
Antibody-antigen complex.
Name 2 different types of phagocyte and explain how they’re different
macrophage- engulf pathogen
neutrophil- first cells at infection site.
Macrophages can engulf over and over again whereas neutrophils self destruct
What is apoptosis?
Programmed cell death.
loss of water can stop what important process?
Metabolic reactions!
Monoclonal antibodies are antibodies produced from….
Genetically identical B-cells (plasma cells) so all identical in structure.
Why are antibodies very specific?
As their binding sites have a very unique tertiary structure that only 1 antigen will fit into.
Cancer cells have antigens called…..
tumour markers.
Pregnancy tests detect the hormone ….
HCG
Why is AIDS dangerous?
As the immune system deteriorates and fails leaving somebody vulnerable to other infections
When do people with HIV develop AIDS?
Not enough helper T-cells- critically low no. of Tcells
What is the enzyme needed for virus replication?
Reverse transcriptase.
What is the use of attachment proteins on HIV?
Help HIV attach to the host helper T-cell.
What could be the target of anti-HIV drugs?
Reverse transcriptase (no replication in host cell)
What does integrase do?
Inserts viral DNA into T-helper DNA.
Explain the role of cytotoxic T-cells in destroying a pathogen.
Makes holes in the cell-surface membrane of the cells infected by the pathogen.
Making the cell freely permeable + die.
Why do less people have AIDS than HIV?
AIDS sufferers have to be infected with HIV
AIDS takes time to develop
Not all people with HIV will develop AIDS.
What 2 things do plasma cells produce?
Memory cells
Complementary antibodies to antigen
