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Biology Year 1 > Chapter 5 - Cell Recognition And The Immune System > Flashcards

Chapter 5 - Cell Recognition And The Immune System Flashcards

1
Q

What are antigens

A

Proteins on the surface of cells which cause an immune response

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2
Q

Why are antigens useful

A

They allow the immune system to recognise

  • Pathogens
  • Cells from the same species (allowing organ transplant)
  • Abnormal body cell eg tumour
  • Toxins
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3
Q

What are antibodies

A

Proteins that bind to antigens to kill pathogens

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4
Q

What is a pathogen

A

An organism that causes disease

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5
Q

What are examples of pathogens

A

Bacteria, fungi, virus

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6
Q

How does a pathogen cause disease

A
  • Destroying host cells

- Or producing toxins

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7
Q

What are the parts of the cellular immune response

A

Phagocytosis

T-Cells

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8
Q

What is phagocytosis

A

The first line of defence

Not specific to any pathogen

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9
Q

What happens in phagocytosis

A
  • Phagocyte identifies foreign antigen (on a pathogen)
  • Engulfs pathogen into phagocytic vacuole
  • releases lysosomes
  • which hydrolyse the pathogen
  • Phagocyte presents the antigens on its surface
  • So is an antigen presenting cell
  • Stimulates the rest of the immune response
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11
Q

What are T cells also known as

A

T-lymphocytes

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12
Q

How are T cells activated

A

By antigens presented on phagocyte

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13
Q

What are the 2 types of T cells

A

T helper cells

Cytotoxic T cells

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14
Q

What do t helper cells do

A

Activate B cells and cytotoxic T cells

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15
Q

What do cytotoxic T cells do

A

Kills cells infected by a pathogen

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16
Q

What does a B do

A

Produce a specific antibody

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17
Q

What does a B cells antibody do

A
  • Forms antigen-antibody complex with complementary antigen
  • Activates the selection of the correct B cell
  • This divides/clones itself
  • Into many copies called plasma cells
  • This is clonal selection
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18
Q

What is clonal selection

A

Where only the specific B cell that forms an antigen-antibody complex is selected to divide into plasma cells

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19
Q

What are plasma cells

A

Clones of the selected B cell with complementary antibodies to the pathogens antigen

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20
Q

What do plasma cells do

A
  • Make monoclonal antibodies
  • These form antigen-antibody complex with antigen
  • Sticks pathogens together, known as agglutination
  • Phagocytes can destroy more pathogens at once (more efficient)
  • When infection is over, plasma cells are saved as memory B cells
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21
Q

Draw and label an antibody

A

Picture on snapchat memories 14 nov

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22
Q

Explain characteristics of antibodies

A

Proteins that have:

  • A specific primary structure
  • Specific tertiary structure
  • Variable region that is complementary to antigen
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23
Q

Explain the primary response to infection

A
  • The first immune response
  • Slow to occur, as it includes phagocytosis, T cells, B cells, and plasma cells
  • Pathogen multiplies so symptoms are felt
  • After infection, memory cells are saved
24
Q

Explain the secondary response to an infection

A
  • Pathogen with same antigen infects you for a second time
  • Immune response is faster and stronger
  • Only need memory B cells to divide into plasma cells which make antibodies for humoral response
  • Memory T cells kill pathogens (cellular response)
  • No symptoms felt
25
Q

Draw graph showing primary and secondary response to infections and explain each part

A

Snapchat memories 14 nov

26
Q

What are monoclonal antibodies

A

Identical antibodies made from the same B cell/plasma cell

27
Q

What are the 2 functions of monoclonal antibodies

A
  • Targeting medication

- Medical diagnosis

28
Q

Explain how monoclonal antibodies can be used to target medication

A
  • Can be used to deliver drugs
  • All cells have specific antigens on their surface
  • Drug can be attached to complementary monoclonal antibody (of cells antigens)
  • Forms antigen-antibody complex
  • Drug can carry out function when arrives at cell eg tumour cell
29
Q

How can monoclonal antibodies be used for medical diagnosis

Eg testing for a disease

A
  • Fix monoclonal antibodies to a plate
  • Add sample of ??
  • Antigen-antibody complexes will be formed if antigen is present in sample
  • Rinse plate to remove inbound antigens
  • Add monoclonal antibody with a colour or enzyme attached (marked)
  • Rinse again
  • Observe to look for marker, if enzyme attached to substrate there will be a colour change???
30
Q

What are vaccines

A

Something containing antigens from a dead or weakened pathogen

31
Q

How do vaccines lead to immunity

A
  • Vaccine stimulates immune response eg antibodies/plasma cells/memory cells
  • If you become infected with pathogen a secondary response will occur and so no symptoms will be experienced
32
Q

What is meant by herd immunity

A

When a higher percentage of a population is immune, there are fewer people to pass on the disease and so risk is reduced for everyone

33
Q

How are vaccines taken

A

Usually by injection

But can be orally

34
Q

What is meant by antigenic variability

A

Where antigens in the surface of pathogens change/vary as pathogens have different strains

35
Q

How does antigenic variability influence vaccination

A
  • New antigen May not be complementary to antibody made by memory cells
  • Therefore if infected again, primary response will occur and symptoms will be felt
36
Q

What is meant by active immunity

A

When the body makes its own antibodies as a result of being infected

37
Q

What is meant by passive immunity

A

When you’re given antibodies by another organism

38
Q

What are the 2 types of active immunity

A

Natural active immunity

Artificial active immunity

39
Q

What is the difference between natural and artificial active immunity

A

Natural is through infection, primary response etc

Artificial is through vaccination and thus memory cells

40
Q

What are the key features of active immunity

A
  • Slow process
  • Long term as memory cells last forever
  • Have to be exposed to antigen
41
Q

What is natural passive immunity

A

What antibodies are given to children by their mother

Eg through placenta or breast milk

42
Q

What is artificial passive immunity

A

When you are given someone else antibodies eg through blood transfusion

43
Q

What are the key features of passive immunity

A
  • Fast/immediate protection
  • May only last short term as foreign antibodies may be broken down by body
  • Doesn’t make memory cells
  • No exposure to antigen
44
Q

What is the ELISA test

A

A test to see if patients have a specific antibody or antigen

45
Q

What does ELISA stand for

A 
Enzyme
Linked
Immuno 
Sorbet
Assay (test)
46
Q

What are the 2 types of ELISA test and what are they testing for

A

Direct ELISA - Test for antigens

Indirect ELISA - Test for antibodies

47
Q

Explain direct ELISA test

A
  • Immobilised antibodies are attached to a well (plate)
  • Sample added (eg blood plasma)
  • If it contains antigen, a-a complex will be formed
  • Rinse to remove unbound antigens
  • same Antibody with an enzyme attached is added
  • Rinse to remove inbound antibodies and enzyme
  • Add substrate, if there is a colour change it is positive, because substrate will have attached to enzymes which will mean antibodies are present and have attached to antigens
48
Q

Explain indirect ELISA test

A
  • Antigens are attached to a well (plate)
  • Sample added
  • If contains complementary antibody, a-a complexes will be formed
  • Rinse to remove unbound antibodies
  • a different antibody is added with an enzyme attached
  • This will only bind if the first antibody is present
  • Rinse to remove unbound antibodies and enzyme
  • Add substrate, colour change of present
49
Q

What does HIV stand for

A

Human Immunodeficiency Virus

50
Q

When infected be HIV, what does it do

A

Attaches to t helper cells, uses them as host cells

51
Q

How does HIV cause AIDS to develop

A
  • Kills or interferes with t helper cells
52
Q

How does AIDS cause bad health

A
  • T helper cells can’t function
  • Immune system can’t stimulate B cells to produce antibodies or cytotoxic T cells to kill infected cells
  • Body can’t produce an adequate immune response to future infections
  • These infections can therefore lead to a deterioration in health and possible death
53
Q

Explain the structure of HIV, using 5 main parts

A
  • LIPID ENVELOPE on outside
  • ATTACHMENT PROTEINS are embedded in this
  • Inside envelope is a protein layer called the CAPSID
  • This encloses two single strands of RNA and enzymes such as REVERSE TRANSCRIPTASE (that catalyses the production of DNA from RNA)
54
Q

How does HIV replicate

A
  • A virus is acellular so needs a host cell
  • Attachment protein on HIV bonds to a protein called CD4, which can be found on t helper cells
  • The HIV reverse transcriptase converts the virus’s RNA into DNA
  • Newly made DNA enters T cells nucleus through nuclear pore, where it’s inserted into DNA of cell
  • HIV DNA creates mRNA which contains instructions for new viral proteins and RNA for new HIV
  • mRNA passes out of nucleus through pore and uses cells protein synthesis mechanisms to make new HIV
  • HIV breaks always from T helper cell, taking a price of its cell surface membrane which they use to form their lipid envelope
55
Q

What are the parts of the hunoral response

A

B cells

Plasma cells

Biology Year 1 (10 decks)

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