2.4 Immunity Flashcards
What are the non-self cells
- Cells from transplants
- Abnormal (cancer) cells
- Cells infected by a virus
Cells from transplants, abnormal (cancer) cells, and cells infected by a virus are all what type of cell
Non-self cells
Define an antigen
Foreign protein, which stimulates an immune response
Describe and explain the process of phagocytosis
- Phatocyte attracted to pathogen as it recognises foreign antigen
- Phagocyte engulfs pathogen by endocytosis, and encloses it into a phagosome
- Phagosome fuses with lysosome
- Lysosome releases enzymes which hydroylse pathogen
- Antigens displayed on cell-surface membrane
How is a phagocyte attracted to a pathogen
It recognises foreign antigen
In what process does a phagocyte engluf a pathogen
Endocytosis
What fuses with each other during phagocytosis
Phagosome fuses with lysosome
What type of response is phagocytosis
Non-specific immune response
What are the two types of phagocytes
Neutrophils and monocytes, which mature to macrophages
Long-livety of neutrophiles
Short lived
Long-livety of monocytes
Mature to macrophages, which are longer-lived
Describe the cellular immune response
- T cell receptor specific for single antigen
- Th cell with complementary antigen binds to antigen presenting cell
- Causes activation of Th cells to rapidly divide by mitosis
- Producing clones
What can clones of Th cells do
- Become T memory cells
- Stimulate the humoral response
- Stimulate cytotoxic T cells
How do cytotoxic T cells result in the death of other cells
Produce the protein perforin, which makes holes in the cell-surface membrane
Describe and explain the humoural immune response
- Antigen binds to surface receptor on B cell
- B cell englulfs by endocytosis, and presents antigens on surface
- T helper cell with complementary receptor binds to antigens
- This stimulates B cell so it is activated, rapidly dividing by mitosis - clonal expansion
- Activated B cell can differentiate into B memory cells or plasma cells
What can activated B cells differentiate into
- B Memory Cells
- Plasma Cells
Long-livety of B Memory cells
Long-lived
Long-livety of plasma cells
Short-lived
What is the purpose of B Memory Cells
Can rapidly divide into plasma cells if the same antigen is encountered
What is the purpose of plasma cells
Produce antibodies
What are antibodies produced by
Plasma cells
When does agglutination occur
When an antigen and antibody bind with each other, forming an antigen-antibody complex
What is the result of an antigen and antibody binding with each other, forming an antigen-antibody complex
Agglutination
What is the purpose of agglutination
Attracts phagocytes to increase the rate of phagocytosis
Define an antibody
Protein secreted by plasma cells which are specific to an antigen
What is the orange label on this antibody
Antigen binding site
What is the light blue label on this antibody
Variable reigon
What is the dark blue label on this antibody
Constant reigon
What is the green label on this antibody
Disulfide Bridge
What is the red label on this antibody
Light polypeptide chains
What is the pink label on this antibody
Heavy polypeptide chains
When does a primary immune response occur
First time after an individual encounters a pathogen
When does a secondary immune response occur
Subsequent times after an individual encounters a pathogen
Why is primary immune response slower than secondary immune response
Fewer T and B cells in circulation
What is the result of primary immune response, that is not the result of secondary immune response
Production of memory cells
Key sentence to include in all immune response questions regarding the secondary immune response
Secondary immune response occurs quicker, and a higher concentration of antibodies are produced
What is the final result of phagocytosis
Pathogen antigens displayed on cell-surface membrane
Describe and explain how the process of vaccination produced antibodies
- Vaccine contains antigen from pathogen
- Antigen binds to receptor on B cell
- B cell engulfs by endocytosis, and presents antigens on surface
- T helper cell with complemtary receptor binds to antigens
- This stimulates/activates the B cell so it rapidly divides by mitosis
- B cells differentiate into memory cells and plasma cell
- Plasma cells produce antibodies
- Memory cells produce plasma cells faster when re-infected by pathogen
Active vs passive immunity: Memory cells
- Active involves memory cells
- Passive doesn’t involve memroy cells
Active vs passive immunity: Introduction of anitbodies
- Active involves antibody production by plasma cells
- Passive involves antibody introduced from outside source
Active vs passive immunity: short or long-term, and why
- Active long-term as anitbody is produced in response to antigen
- Passive long-term as antibody is broken down
Active vs passive immunity: Time taken to work
- Active takes time to work
- Passive is fast-acting
Why is herd immunity neccessary
Not all individuals can be vaccinated
Explain the principale of herd immunity
- If a suffice proportion of the population is vaccinated, then pathogen cannot be transmitted to unvaccinated individuals
- As pathogen destroyed before it reaches vulnerable individuals
On this HIV diagram: What is the pink
RNA
On this HIV diagram: What is the blue
Protein Capsid
On this HIV diagram: What is the green
Reverse Transcriptase enzyme
On this HIV diagram: What is the orange
Lipid envelope
On this HIV diagram: What is the black
Attachment proteins
Where is reverse transcriptase enzyme found within a molecule of HIV
Matrix
Where are the attahment proteins found on a molecule of HIV
Lipid envelope
Describe and explain the process of HIV replicating
- Attachment proteins on virus bind to receptors of T helper cell
- HIV injects RNA into T helper cell
- Reverse transcriptase enzyme converts RNA to DNA
- DNA incorporates itslef into T helper cell chromosome
- DNA transcribed into HIV mRNA
- HIV mRNA translated into viral proteins
- Virus assembled and released from cell
What cells does HIV affect
T helper cells
Does does HIV enter the T helper cells
Injects RNA
How does HIV affect the immune system
- HIV destroys T helper cells
- So fewer B cells are activated/stimulated
- Less antibodies produced
Explain how HIV affects antibody production
- HIV destorys T helper cells
- Fewer B cells are activated/stimulated
- Less antibodies produced
Define a monoclonal antibody
Antibodies with the same tertiary structure, produced from cloned plasma cells
Why can monoclonal antibodies be used to treat disease
Binds and carries drugs to specific antigens/receptors
What type of immunity does monoclonal antibodies use the principal of
Passive immunity
Describe and explain the process of using an ELISA test
- Antigen from sample being tested is attached to well
- First antibody has tertiary structure, which is complementary in shape to the antigen added, and so binds
- Add second antibody with enzyme attached, that binds to first antibody
- Substrate added
- Colour change, due to enzyme
What does the first line on antibody test strip prevent and how
- False negatives
- Shows how original antibody has moved up the strip
Explain why antibodies are specific to one antigen
- Variable reigon has a specific primary structure
- So binding site has a specific tertiary structure
- Binding site is** complementary in shape to antigen** so binds
- To form an **antibody-antigen complex **
Define a pathogen
A microorganism that causes an immune response, and bodily harm
Why is there no vaccien for HIV
- High rate of mutation
- High genetic diversity
Diagram to show how monoclonal antibodies can deliver drugs to specific antigen/receptor
What is/what does agglutination cause
Cells to join/clump together
