3.2.4 Cell recognition and the immune system Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What specific molecules on cell surfaces enable identification by the immune system?

A

Proteins with specific tertiary structures that act as antigens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the four things the immune system can identify using specific molecules on cell surfaces?

A

Pathogens, non-self cells (e.g. cells from other organisms of the same species), abnormal body cells (e.g. cancer cells), toxins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the role of proteins on the surface of cells?

A

To act as antigens with specific tertiary structures which are recognized by the immune system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give an example of an abnormal body cell that the immune system can identify.

A

Cancer cells displaying abnormal antigens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What term describes cells from other organisms of the same species that can be identified by the immune system?

A

Allogeneic cells identified as non-self.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What feature of toxins allows the immune system to identify them?

A

The specific shape of their antigenic determinants.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does the immune system differentiate between self and non-self cells?

A

By recognizing antigens; self-cells display self-antigens while non-self cells display foreign antigens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the definition of an antigen?

A

An antigen is a molecule, often a protein, with a specific tertiary structure that triggers a specific immune response by being recognized as non-self by the immune system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does antigen variability affect disease?

A

Antigen variability caused by genetic mutations or recombination changes the specific proteins on a pathogen’s surface. This helps pathogens evade immune recognition, leading to persistent or recurrent infections. For example, the influenza virus frequently alters its antigens, requiring updated vaccines.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does antigen variability impact disease prevention?

A

Antigen variability reduces vaccine effectiveness because changes in surface antigens mean the immune system may not recognize the pathogen. Vaccines such as the flu vaccine must be updated regularly to match these new antigenic forms and maintain protection.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is phagocytosis?

A

The process by which phagocytes engulf and ingest pathogens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to pathogens after phagocytosis?

A

Ingested pathogens are destroyed by lysozymes within the phagocyte.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the cellular response in the immune system?

A

The activation of T lymphocytes in response to a foreign antigen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do T lymphocytes respond to a foreign antigen?

A

T lymphocytes bind to antigens presented on the surface of antigen-presenting cells, leading to their activation and clonal expansion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the role of antigen-presenting cells in the cellular response?

A

Antigen-presenting cells display antigens on their surface to activate T lymphocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the role of helper T cells (TH cells) in the immune response?

A

Helper T cells stimulate cytotoxic T cells (TC cells) to kill infected cells, activate B cells to produce antibodies, and enhance the activity of phagocytes by releasing cytokines which amplify phagocytic activity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the humoral response?

A

The activation of B lymphocytes in response to a foreign antigen, leading to the production of monoclonal antibodies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is clonal selection in the humoral response?

A

The process by which specific B lymphocytes with complementary receptors to the foreign antigen are activated and cloned.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do B lymphocytes release after activation?

A

B lymphocytes release monoclonal antibodies specific to the foreign antigen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the definition of an antibody?

A

An antibody is a protein produced by B lymphocytes that binds specifically to a complementary antigen, triggering its destruction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the structure of an antibody?

A

Antibodies consist of four polypeptide chains (two heavy chains and two light chains) held together by disulfide bonds. They have a variable region that binds to a specific antigen and a constant region.

22
Q

What happens when an antigen-antibody complex forms?

A

The formation of an antigen-antibody complex leads to the destruction of the antigen through agglutination and phagocytosis of bacterial cells.

23
Q

What is the role of plasma cells in the immune response?

A

Plasma cells are activated B lymphocytes that produce and release large quantities of monoclonal antibodies during the primary immune response.

24
Q

What is the role of memory cells in the immune response?

A

Memory cells are long-lived B lymphocytes that remain in the body after the primary immune response, enabling a faster and stronger secondary immune response upon re-exposure to the same antigen.

25
Q

How do vaccines provide protection against disease?

A

Vaccines contain antigens from a pathogen, stimulating the production of memory cells without causing disease, leading to immunity.

26
Q

What is herd immunity?

A

Herd immunity occurs when a significant portion of a population is vaccinated, reducing the spread of the disease and protecting individuals who are not immune.

27
Q

What is active immunity?

A

Active immunity involves the production of antibodies by the immune system after exposure to an antigen, either through infection or vaccination.

28
Q

What is passive immunity?

A

Passive immunity involves the transfer of antibodies from another source, such as maternal antibodies through the placenta or injection of antiserum, providing temporary immunity.

29
Q

What are the differences between active and passive immunity?

A

Active immunity is long-lasting, involves memory cell formation, and takes time to develop, while passive immunity is immediate, short-term, and does not involve memory cells.

30
Q

What is the structure of HIV?

A

HIV consists of an RNA genome enclosed in a capsid, surrounded by a lipid envelope embedded with glycoproteins.

31
Q

How does HIV replicate in helper T cells?

A

HIV binds to the CD4 receptors on helper T cells using its glycoproteins, fuses with the cell membrane, and releases its RNA. Reverse transcriptase converts the RNA into DNA, which integrates into the host’s genome. The host cell machinery produces new viral particles.

32
Q

How does HIV cause the symptoms of AIDS?

A

HIV destroys helper T cells, reducing their numbers and impairing the immune response. This makes the body susceptible to opportunistic infections and cancers.

33
Q

Why are antibiotics ineffective against viruses?

A

Antibiotics target bacterial structures and metabolic pathways, such as cell walls and ribosomes, which are absent in viruses. Consequently, antibiotics cannot disrupt viral replication.

34
Q

How are monoclonal antibodies used in targeting medication?

A

Monoclonal antibodies are attached to therapeutic drugs. These antibodies bind specifically to antigens on target cell types, delivering the drug directly to the diseased cells and minimizing side effects.

35
Q

How are monoclonal antibodies used in medical diagnosis?

A

Monoclonal antibodies are used to detect specific antigens or proteins in diagnostic tests, such as detecting biomarkers for diseases like cancer or infections.

36
Q

What are some ethical issues associated with the use of vaccines?

A

Ethical issues include concerns about testing vaccines on animals or humans, the cost and accessibility of vaccines, and the potential side effects.

37
Q

What are some ethical issues associated with the use of monoclonal antibodies?

A

Ethical issues include the use of animals in their production, the cost of treatment, and the potential for side effects.

38
Q

What is the purpose of the ELISA test?

A

The ELISA test detects the presence and quantity of specific antigens or antibodies in a sample, such as diagnosing infections like HIV. Detecting antigens allows for early diagnosis of disease, while detecting antibodies indicates an immune response to a pathogen.

39
Q

How does the ELISA test work?

A

The test involves attaching an antigen or antibody to a surface, adding the sample, and using enzyme-linked antibodies that produce a color change to indicate a positive result.

40
Q

Describe the role of the disulfide bridge bonds in an antibody

A

joins two (different) polypeptides

41
Q

Explain why antibodies will only bind with specific antigens.

A

antibodies have a variable region that has a specific amino acid sequence OR primary structure

the shape OR tertiary structure of the binding site is complementary to specific antigens

forms a complex between the antigen and antibody OR forms an antigen-antibody complex

42
Q

Describe how phagocytes destroy pathogens.

A

engulfs/endocytosis

forms a vesicle/phagosome AND fuses with a lysosome

enzymes/lysozymes digest/hydrolyse the pathogen

43
Q

What is an antigen?

A

a molecule/protein/glycoprotein

that stimulates an immune response

44
Q

Other than pathogens, give two types of cell that may stimulate an immune response.

A

cells from other organisms OR cells from transplants

abnormal/cancer/tumour cells

cells infected by a virus

own/host cells in an autoimmune disease

45
Q

Explain how the release of antibodies stimulates the process of phagocytosis.

A

antibodies bind to antigens

OR

antibodies are markers/opsonins

OR

antibodies form antigen-antibody complexes

antibodies cause clumping/agglutination

OR

antibodies attract phagocytes

46
Q

Explain why a high mutation rate makes it difficult to develop a vaccine.

A

high mutation rate leads to the antigens changing

OR

high mutation rate leads to antigenic variability

vaccines (often) contain a specific antigen

antibodies will not be complementary to a changed antigen

OR

antibodies will not bind to changed antigens

47
Q

Explain how HIV affects the production of antibodies when AIDS develops.

A

less/no antibodies produced

because HIV destroys helper T cells

so few/no B cells are activated

OR

few/no B cells undergo mitosis

OR

few/no B cells differentiate into plasma cells

48
Q

Explain how the destruction of T cells by HIV eventually leads to death of the affected individual.

A

nsufficient/no T cells to activate B cells

OR

insufficient/no T cells to activate the immune system

individual unable to fight off infections/cancer/diseases

OR

individual more prone to infections/cancer/diseases

example of infection/cancer/disease (e.g. TB/tuberculosis or pneumonia)

49
Q

What is an antibody?

A

a protein/immunoglobulin specific to an antigen

produced by B cells OR secreted by plasma cells

50
Q

Explain how vaccines can be used to protect people against disease.

A

vaccines contain antigens

OR

vaccines contain dead/weakened pathogens

memory cells are made

on second exposure to the antigen/pathogen, memory cells (divide into plasma cells that) produce antibodies

memory cells rapidly (divide into plasma cells that) produce antibodies

OR

memory cells (divide into plasma cells that) produce more antibodies

antibodies destroy pathogens

51
Q

Explain the differences between active and passive immunity.

A

active immunity involves memory cells, passive immunity does not

active immunity involves the production of antibodies by plasma cells

passive immunity involves antibodies being introduced into the body from outside

active immunity is long term because antibodies are produced in response to antigens

passive immunity is short term because the antibodies given are broken down

active immunity can take time to develop, passive immunity is fast acting