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Biology > Topic 2-Immunity > Flashcards

Topic 2-Immunity Flashcards

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1
Q

What is the specific immune response?

A

Recognising foreign cells and targeting pathogenic cells

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2
Q

What are antigens used to recongnise? (4)

A

Pathogenic cells
Abnormal body cells
Toxins
Cells from other individuals of the same species

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3
Q

What is the importance of antigens in defending againts pathogens?

A

Antigens are used as a binding site by surface proteins of phagocytes.
The pathogen is engulfed and digested
the antigen on the pathogen is complimetary to surface receptor of the phagocyte
It then recruits cells of the immune system leading to a specific immune response

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4
Q

How are antigens produced?

A

By organisms own body cells and are self-antigens

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5
Q

What are non-self antigens?

A

Antigems not produced by the body’s own cells

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6
Q

Why do some pathogens exhibit antigen variablity?

A

Antigens present on their surface change frequently due to gentic mutations.

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7
Q

Why is antigen variability a problem for the immune system?

A

Antigens on pathogens change shape due to gene mutations creating new strains, so vaccine or prior infection no longer provides immunity. B memeory cell receptors cannot recognis r bind to changed antigen on secondary response. Specific antibodies are no ,onger complementary

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8
Q

What molecules on outer surface membranes act as antigens?

A

Glycolipids
Glycoproteins

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9
Q

How are phagocytes stored and distributed?

A

Stored in bone marropw and distributes through the blood.

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10
Q

What are the two types of phagocytes?

A

Neutrophils
Macrophages

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11
Q

How does phagocytosis lead to the stimulation of the specific immune response?

A

Phagocytosis leads to presentation of antigens where antigens where antigens are displayed on the phagocyte cell surface immune membrane, stimulating the specific immune response

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12
Q

Describe phagocytosis of pathogens

A

-The phagocyte is attracted by chemicals and moves pathogens
-The phagocyte attaches to chemicals on the antigen by its receptors
-They engulf the pathogen to form a phagosome
-Lysosome fuses with the phagosome and releases lysozymes which are hydrolytic enzymes
-The lysozymes hydrolyse/digest pathogen

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13
Q

What is the response to chemical response in phagocytes known as?

A

Chemotaxis

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14
Q

What is endocytosis?

A

The process of surrunding and engulfing a pathogen in a phagocytic vacuole.

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15
Q

What is a phagososme?

A

Phagocytic vacuole formed around a pathogen once engulfed by a phagocyte.

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16
Q

Describe what are lysosomes?

A

Membrane organelles that contain digestive enzymes called lysozomes which digest unwanted material in a cell.

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17
Q

What is the function of lysosmes in phagocytosis?

A

It fuses with the membrane of the phagososme to form a phagolysome.
It then releases lysozomes to digest pathogen
These digestive enzymes destroy the pathogen

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18
Q

What is secreted as a sign of a dead neutrophil?

A

Pus

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19
Q

How do cytotoxic T cells kill infected cells?

A

They produce a protein called perforin that makes holes in the cell-surface membrane. These holes mean the cell membrane becomes freely permeable to all substances and the cells die as a result.

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20
Q

State two ways in which macrophages carry out phagocytosis differently than neutrophils

A

-Dont destroy the pathogen completely and cuts it up instead
-It displays its antigens on their surface so recognised by lymphocytes

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21
Q

Where/When are T-lymphoctes produced?

A

In the bone marrow before birth

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22
Q

What are the physical properties of T- lymphocytes?

A

Smaller than phagocytes
Large nuclues that takes up most of cell

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23
Q

Where do immature T-lymphotes leave bone marrow to mature?

A

In the thymus- gland in the chest

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24
Q

Name the receptors on the surface of T- lymphoctes

A

T cell receptors

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25
What are the two types of T-cellls?
Helper T-Cell Cycotoxic T-cell (KILLER)
26
When are T cells activated?
When they encounter and bind to specific antigen presented by host cells.
27
What are the function of antigen presenting cells?
-They recruit other cells to produce specific immune response -T-cells bing to complimentary antigen on these cells become sensitivised and divies to clone cells
28
Describe the response and function of T lymphocytes to a foreign antigen
Specific T lymphocytes with complementary receptors bind to antigen on antigen presenting cell. They are activated and divide by mitosis to form clones which stimulate: Cytotoxic T cells- Kill innfected cells/tumour cells Specific B cells- Humoral response Phagocytes-E ngluf pathognes by phagocytosis develop into memory cells- enable rapid response in future
29
Where to B lymphocytes mature and spread to?
They remain in bone marrow until mature then spread through body concentrating liver and spleen.
30
Why are millions of B lymphocytes produced?
As they mature, the genes coding for antibodies are changed to code for different antibodies.
31
What two types of cells do B lymphocytes differentiate into?
Plasma Cell Memory Cell
32
What type of molecule does an antibody molecule form that combines with one type of antigen?
Glycoprotein receptor
33
What is clonal selection?
When a foreign antigen enters the blood, specific b lymphoctes with complementary receptors binds to the antigen. The antigen enters the B cell by endocytosis. Helper T cells bind to processed antigen and stimulate b cells causing them to divides rapidly by mitosis to form clones- some differentiate into B plasma cells and some into B memeory cells
34
What do clones of B lymphocyte become to do?
Plasma Cells- Secrete lots of antibody molecule Memory Cells- Circulationg in blood
35
Describe in a lot of detail the structure of an antibody
-It is a globular glycoprotein called immunoglobulins -It has a quaterny structure (Y) has two heavy polypeptide chains bonded by disulfide bonds to two light polypeptide chains -Polypeptide has a constant and variable region -Variable region tip og Y shape where antibody attaches to antigen to form antigen antibody complex -Hinge region only present in some antibodies where disulfide bonds join heavy chains to give flexibility.
36
Draw and label an antibody
37
What does it mean it mean that antigen and antibody have complementary shapes?
Their molecular shapes fit into one another.
38
What happens when an antibody collides randomly with a foreign cell that contains non self antigens with a complimentary shape?
It bonds so two molecules combine to form an antigen antibody complex.
39
What is agglutination?
When antibodies bind to move more than one pathogen at a time which causes groups of pathogen to clump together.
40
Describe the primary immune response.
After clone selection and expansion B lymphocytes become plasma cells and secrete lots of antibody molecules. Plasma cells are shortlived so some die others become memory cells. The primary immune response is slow.
41
Describe the secondary immune response.
The memory cells recognise the antigen and divide quickly, the cells differentiate into plasma cells and the infection is removed very fast.
42
What two responses is the immune response split into?
Humoral response- When T-cells and other immune system cells that they interact with form cellular response Cellular reponse- B cells, clonal selection snd production of monoclonal antibodies.
43
What is active immuity?
When your immune system makes its own antibodies after stimulated by antigen
44
Whats difference between the two types of active immunity?
Natural- Immune after catching disease Artificial- Become immune after vaccination and a harful dose of antigen.
45
What is passive immuntiy?
Immunity you get from being given antibodies made by different organisms.
46
What is the difference between the two types of passive immunity?
Natural- When babies become immune from the antibodies given by their mother in the palcenta and through breastmilk. Artificial- Being given transfusion of antibodiesfor example blood donations or being injected with the antibodies.
47
State 3 differences between active and passive immunity
Active require exposure to antigen passive dosent Active produces memory cells passive dosent Active produces long term immunity as antibodies are not easily broke down whereas passive has only short term protection as antibodies are easily broken down.
48
What is herd immunity?
hen a sufficiently large proportion of the population has been vaccinated and therefore immune making it difficult for pathogen to spread within the population
49
What is a vaccine?
A suspension of antigens intentionally put into the body to induce artificial active immunity.
50
What are the two types of vaccines?
Live attenuated vaccine Inactivated vaccine.
51
What are two ways vaccines are administrated?
Injection into muscle or vein Orally
52
How are less effective vaccines made more effective?
Administrating booster vaccines.
53
Give 3 problems of vaccines (not ethical)
People with defective immune systems may have poor reponse Antigenic variation- is where antigens of vaccines do ot trigger immune response as some eukaryotes have too many antigens on their surface or mutate so it is hard to provide effective vaccines quickly Anitgenic concealment- some pathogens hide from the immune system by hididng in living cells they parasite cells like t cells and macrophages or coat themselves in host proteins.
54
Describe what attenuated vaccines are and give an example
Vaccines that contain whole pathogens that have been weakened, they multiply and trigger primary immune response. They are stonger and long lasting but unsuitable for people with weak immune systems. -MMR vaccine
55
Decribe what and inactivated vaccine is and give an example.
Vaccines with killed pathogens in it and cannot cause disease. Their suitable for those with weak immune systems and because theyre weak they need booster doses. -Polio vaccine
56
What is an adjuvant and give an example
A substance that enhances the bodys immune system to respong to an antigen like aliminium salts
57
Why was the eradication of smallpox succesful?
THe virus was stable The vaccine was live attenuated symptons easy to indentify No carriers but humans so easy to break transmission pathway
58
Why may some people have allergic reactions to inactivated vaccines?
Adjuvants may be added to the subnit of the pathogen to strengthen/lengthen immune response.
59
For disease to be eradicated by vaccines they shouldnt:
-Mutate -Have any life cycle including other organisms -Have symptoms hard to identify/ diagnose
60
What is a retrovirus and give an example?
Viruses that have the ability to make DNA from RNA becaiuse they have a reverse transcriptase.
61
How is HIV transmitted and give examples.
Direct exchange of bodily fluids. Sexual intercourse Sharing needles breast milk
62
What are the key componenets of a HIV structure?
Two RNA strands Proteins Enzyme reverse transcriptase Caspid Viral envelpope consisting of lipid bilyaer and glycoprotiens
63
What is a capid?
Protein coat
64
What is the lipid bilayer in HIV derived from?
The cell membrane of the host helper T-cell that the particle escaped from.
65
Draw a HIV structure
66
Describe the replication of HIV replicated in Tcells?
HIV attachment proteins attach to receptors on helper T cell. Lipid envelope fuses with cell surface membrane releasing caspid into cell, capid uncoats releasing viral RNA and reverse transcriptase Reverse transcriptase converts viral RNA to DNA\Viral DNA is inserted into helper T cell DNA Viral caspid/protein are produced DNA transcribed into HIV mRNA and HIV mRNA translated into new HIV proteins Viral particles assemble and released from the cell
67
What does AIDS stand for?
Accquied Immune Defiency sydrome
68
What are opportunistic diseases?
Diseases that would cause minor issues in healthy individuals cause AIDS carriers to be very ill.
69
How does HIV avoid being sought out and destroyed?
It repeatedly changes its protein coat
70
What is the treatment for AIDS?
No cure but there are drugs that slow down the spread of the viurs.
71
What are the symptoms like immediately after HIV infection?
Mid-flu like symptons.
72
Expalin why antibiotics ineffective against viruses?
They are particles not cells so they have no metabolic processes or cell structure for the antibiotics to disrupt. In addition they have no bacterial enzymes
73
What are the two ways monoclonal antibodies are used?
Thereputically Diagnostically
74
Explain how monoclonal antibodies used in medical diagnosis
Monoclonal antibodies have specific tertiary structures which will be complementary to antigen associated with diagnosis. A dye/stain/flourecent marker is attached to the antibody. Antibody binds to receptor antibody fporminf antigen- antibody complex
75
What hormone does pregnancy tests detect?
hCG
76
Give three theraputic uses of monoclonal antibodies
-Targets cancer treatment -Prevents blood cloting -Prevents rejection of organ transplants
77
How have scientists overcome immune response triggered by humans when they recieve antibodies from an animal?
They genetically modify antibody polypeptide chain so the amino acid sequences are human. They alternate position and type of sugar group so hevay polypeptide chain reflect those in human antibodies.
78
Give ethical issues concerning vaccination
Tested on animals Payed volunteers may be pressured due to finanacial status Parents put child at greater risk by nit recieving a vaccine Poor countries cannot afford the vaccine and suffer deaths
79
What is an ELISA test used for?
To test if a patient has any antibodies to a certain antigen or vice versa.
80
What is the process of a direct ELISA test?
You attach a sample with potential antigens to well. Add complementary monoclonal antibodies with enzymes attached and it will bind to antigens if present. Wash well to remove any unbound antibodies which can create false positives. Add substrate, enzymes create products that cause a colour change which is a poitive result.
81
Explain the different types of Elisa testing
Direct- single antibody complimentary to antigen used Indirect- Primary and secondary antibodies used
82
Explain how antibodies lead to the destruction of pathogens
Antibodies bind to antigens on pathogens forming an antignen-antibody complex. Antibodies have specific tertiary structure so its binding site binds to complementary antigen. Each antibody binds to 2 pathogens at a time causin agglutination. Antibodies attract phagocytes. Phagocytes bind to the antibodies and phagocytose many pathogens all at once
83
What is the process of indirect elisa testing?
Attach specific antigens to well. Add sample with potential antibodies and wash well Add complementary monoclonal antibodies with enzymes attached, these bind to antibodies if present Wahs well to remove unvound antibodies Add substrate and enzyme creates colour change for positive result
84
Suggest the purpose of a control well in the elisa test
Compare to to test to show only enzyme causes colour change Compare to test that all unbound antibodies have been washed away
85
Suggest some talking points when evaluating methodolgy (effectivness of testing) for use of vaccines and monoclonal antibodies
- Sample size must be large to be representative -Paricipants must be diverse in age,sex,ehtincity and health -Placebo groups used for comparison? DUration of the study long enough to show long term effects Double blind trial?
86
Suggest some points to consider when evaluating evidence and data relating to the use of vaccines and monoclonal antibodies
What side effects were observed, and how frequently did they occur? Was a statistical test used to see if there was a significant difference between start & final results? Was the standard deviation of final results large, showing some people did not benefit? Did standard deviations of start & final results overlap, showing there may not be a significant difference? What dosage was optimum? Does increasing dose increase effectiveness enough to justify extra cost? Was the cost of production & distribution low enough?
87
Explain how monoclonal antibodies can be used in medicla treatments
Monoclonal antibodies have specific tertiary stuctures/ binding sites. Thhis is complelmentary to antigen found on the specific cell. A theraputic drug will be attched to antibody. Antibody binds to specific cell and antibody- antigen comllex formed delivering drug
88
What is a vaccine?
An injection of antigens from attenuated [athogens that stimulate the formation of memory cells
89
What are antigens?
A foreign molecule that stimulates an immune response leading to the production of an antibody
90
How can HIV cause symptoms of AIDS
HIV specifically attacks helper T cells and kills/ interrupts their normal process, without sufficient number, the immune system cannot stimulate cytotoxic T cells that kill cells infected by pathogens many cells destroyed/infected. Inadequate immune response means people become more susceptible to other infections and cancers.
91

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