Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Section 2 - Cells: 5. Cell recognition and the immune system > Flashcards

Section 2 - Cells: 5. Cell recognition and the immune system Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is an infection

A

The interaction between pathogens and the bodies defence systems

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

What are the two types of defence mechanisms

A
  • Non-specific (immediate)
  • Specific (longer lasting)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the non-specific defence system

A
  • Physical barriers
    eg. Skin, HCl in the stomach, mucus on epithelial cells, etc.
  • Phagocytosis (white blood cells engulf pathogens)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the process of Phagocytosis

A
  • Phagocyte is attracted to the pathogen and moves towards it
  • Antigen of the pathogen binds to the cell-surface receptors on the phagocyte
  • Phagosome begins to form as the pathogen is engulfed
  • lysosomes move towards the phagosome, containing lysozymes (digestive enzymes)
  • Lysosomes release lysosomes into the phagosome, hydrolysing the pathogen to break it down.
  • Non-self antigen is presented on the surface of the phagocyte, triggering a specific immune response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why do phagocytes have a lobed nucleus

A

To allow the cell to pass through blood vessels more quickly

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

What is a phagosome

A

The vesical that contains the engulfed pathogen

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

What enzymes hydrolyse the pathogens in phagocytosis

A

lysozymes, stored in the lysosomes

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

What happens to the products of the breakdown of pathogens in phagocytosis

A
  • Can be absorbed by the phagocyte
  • Leave by exocytosis
  • Non-self antigens are presented on the cell-surface membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two stages of the specific immune response

A
  • Cell mediated response
  • Humoral response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the two lymphocytes associated with the specific immune response

A
  • T-Lymphocytes: Mature in the thymus gland
    (cell-mediated response)
  • B-Lymphocytes: Mature in the bone marrow
    (humoral response)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the process of the cell mediated response

A
  • Phagocyte presents non-self antigen on it’s surface
  • T-helper cell binds to the antigen
  • T cell is activated and cloned by mitosis to…
    • Become memory cells that circulate the blood/tissue until a future infection
    • Activate cytotoxic T cells that produced perforin (protein that makes holes in the cell membrane of infected cells, killing them)
    • Stimulate phagocytosis by phagocytes
    • Bind to B cells to stimulate the humoral response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the process of the humoral response

A
  • B cells take in foreign antigens and present them on their surface
  • Activated T-Helper cells bind to these non-self antigens, stimulating the B cells to clone by mitosis to become…
    • Plasma cells, producing antibodies as a primary response
    • Memory cells, to produce antibodies in a future infection as a secondary response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do the lymphocytes recognise Non-self cells as foreign

A
  • In a foetus, around 10 million lymphocytes are constantly colliding with other cells, each with receptors complementary to different antigens
  • Any lymphocytes that recognise self antigens die, or are suppressed
  • In adults, lymphocytes released from the bone marrow that recognise self cells also undergo programmed cell death (apoptosis), so no clones are made
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an antibody

A

Protein with a specifically shaped binding site, complementary to a specific antigen

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

When are antibodies produced in the immune response

A

Synthesised by the B Cells as part of the humoral response

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

How many polypeptide chains make up an amino acid

A

4
- 2 heavy chains
- 2 Light chains

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

Where is the variable region of an antibody located

A

At the end of the light polypeptide chains

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

How are the polypeptide chains joined in an antibody

A

Disulphide bridges, acting as hinges

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

How many antigen binding sites are located on each antibody

A

2, one at the end of each variable region

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

Where is the protein receptor binding site located in an antibody

A

At the base, on the opposite end to the antigen binding sites

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

How can antibodies lead to the destruction of a pathogen

A
  • Agglutination
  • Stimulate phagocytosis
22
Q

What is Agglutination

A

When 2 pathogens bind to one antibody, and multiple antibodies can bind to one pathogen.
This causes the pathogens to clump together, preventing them from spreading throughout the body, and making them easier for phagocytes to locate

23
Q

What are monoclonal antibodies

A

A single type of antibody that can be isolated and cloned for many uses

24
Q

How are monoclonal antibodies produced

A
  • Mouse is injected with a pathogen, triggering an immune response
  • Pancreas removed and antibody producing plasma cells are harvested
  • B cells are fused with Tumour cell (can replicate by binary fission), to give an hybridoma cell.
  • Hybridoma is cloned, giving an endless supply of monoclonal antibodies
25
Q

What are the 3 main uses of monoclonal antibodies

A
  • Targeting medication (Direct/Indirect monoclonal antibody therapy)
  • Medical diagnosis
  • Pregnancy tests
26
Q

What is the process of direct monoclonal antibody therapy

A

Antibodies specific to cancer cells are given to the patient, so bind to them an block chemical signals, preventing growth and replication

27
Q

What is the process of indirect monoclonal antibody therapy

A

Drugs to kill cancer cells are attached to the specific antibody, and are then injected into the patient, so the when the antibodies bind to the cancer cells, they are killed

28
Q

How are monoclonal antibodies used for medical diagnosis

A

Antibodies react with the non-self antigens to give a measure of the level of antigens in the blood

29
Q

How are monoclonal antibodies used in pregnancy tests

A
  • Human chorionic gonadotrophin (HCG) is found in the urine of pregnant women
  • In the test, antibodies specific to this HCG have coloured particles attached to them, and bind to the HCG is it is present
  • The ‘HCG-Antibody-colour’ complexes move along the strip until trapped in a coloured line.
30
Q

What are the ethical issues with using monoclonal antibodies

A
  • Process requires cancer to be induced in mice

Saves human life, so is justified

  • Treatment for multiple sclerosis lead to several deaths

There has been many successful treatment, and
patients are warned of risks

  • Human trials in 2006 lead to healthy volunteers having organ failure

Problems in trials were delt with

31
Q

What is immunity

A

The ability of an organism to resist infection

32
Q

What is passive immunity

A
  • No direct contact with the pathogen (non-self antigen)
  • Antibodies are introduced from an external source
  • Short term, as body can’t produce antibodies, so will run out
33
Q

What is an example of passive immunity

A
  • Foetal immunity: Mother to baby (i.e. antibodies in breast milk)
  • Anti-Venom: Introduces antibodies to kill toxins
34
Q

What is active immunity

A
  • Direct contact with the pathogen (non-self antigen)
  • Stimulates an immune response, so the body produces antibodies
35
Q

What is natural active immunity

A
  • Individuals are infected with the disease, leading to an immune response, producing antibodies
  • Symptoms of the condition are likely during first infection
  • Long term, as memory cells can produce antibodies for years after
36
Q

What is artificial active immunity

A
  • Inducing an immune response through immunisation (i.e. Vaccines)
  • Dead/inactive form of the pathogen is injected
  • Memory cells are produced so allows for long term protection
37
Q

What is heard immunity

A

Arises when a large enough proportion of the population is immune, so it is difficult for the pathogen to spread, as it is unlikely for an infected person to contact a vulnerable person

38
Q

What are the features of a successful vaccination program

A
  • Economically viable
  • Few side-effects
  • Sufficient means of production, transport and storage
  • Means of administering the vaccine
  • Possible to reach heard immunity
39
Q

Why might a vaccination programme fail

A
  • Fails to induce immunity in certain individuals
  • Vaccine may cause disease/infection
  • Antigenic variability: (Mutating pathogens may change antigens, so antibodies no longer work)
  • No vaccines available for certain infections
  • Pathogens can ‘hide’ from the immune system (in cells/out of reach of antibodies)
  • Patient objections
40
Q

What are some ethical issues with vaccinations

A
  • Expensive (money could be invested in cures)

Reaching heard immunity will save lives

  • Individual health risks

Greater benefits for the whole population

  • Ineffective vaccines may lead to spread

Potential lives saved justify risk

  • To be more effective, all should be vaccinated (compulsory?)

heard immunity can be reached with most (doesn’t have to be all)

  • Side effects could cause long term damage

Symptoms of disease would be worse

  • Risks during testing

Tested on animals first (raises other ethical issues)

41
Q

What is HIV

A

Human immunodeficiency virus, causes AIDS

42
Q

What is AIDS

A

acquired immune deficiency syndrome, caused by HIV

43
Q

How does HIV replicate

A
  • HIV enters bloodstream
  • Attachment proteins bind to CD4 proteins on T-helper cells
  • Capsid fuses with the T-helper cell membrane
  • RNA and enzymes enter the host cell
  • Enzymes reverse transcriptase converts the RNA to DNA
  • New DNA moves into the host’s nucleus
  • HIV DNA in the host codes for mRNA that will produce new viral proteins
  • New HIV particles break away from the host with a piece of the cell-surface membrane forming the lipid envelope
44
Q

What cells are usually the host of HIV replication

A

T-helper cells

45
Q

What are the protein receptors on the T-helper cells that the HIV binds to

A

CD4 protein receptors

46
Q

What enzyme is within the capsid that enters the host during HIV replication

A

reverse transcriptase

47
Q

How does HIV cause AIDS

A
  • HIV interferes with the normal functioning of the T-Helper cells
  • This means the T-Helper cells can’t stimulate the production of cytotoxic T-Cells/antibodies
  • Leads to the inability to fight infection (causing death)
48
Q

What is the ELISA test

A

Enzyme link immunosorbent assay, uses antibodies to detect the presence and quantity of a protein in a sample

49
Q

What is the process of the ELISA test

A
  • Apply the sample to a surface, to which all the antigens will attach
  • Wash to remove the unattached antigens
  • Add the antigen specific antibody and leave to bind
  • Wash to remove excess antigens
  • Add a second antibody with an enzyme attached to bind to the first antibody
  • Add the colourless substrate of the enzyme (enzyme causes colour change)
  • Quantity of antigen present is relative to the intensity of the colour

Can detect HIV, tuberculosis, hepatitis, etc.

50
Q

Why are antibiotics ineffective against viruses (eg. HIV)

A
  • Antibiotics inhibit the enzymes required to for the peptide cross-linkages in bacterial cell walls, making the cells weaker so they bust during osmosis
  • Viruses rely on host cells, and don’t have their own structures to be disrupted
    + Viruses are within the bodies cells, so can’t be reached by the antibiotics.

Biology (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions