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Biology Unit 4 > Immunity > Flashcards

Immunity Flashcards

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1
Q

Antigens

A

Proteins found on the surface of cells. Foreign antigens trigger the immune response

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2
Q

Non-Specific Response

A

1) Inflammation: Site of infection becomes red, swollen and painful
- Immune system cells recognise antigens as foreign. They release cytokines that trigger inflammation.
- Vasodilation increases blood flow so more W.B.C reach the area
- Immune system cells then destroy the pathogen

2) Interferons: When cells become infected by a virus they produce Interferons.
- Interferons prevent viruses spreading by Preventing viral replication of proteins and they activate specific immune cells Eg T cells

3) Phagocytosis and lysozyme:
A phagocyte (macrophage) recognises foreign antigens.
- The cytoplasm of the macrophage engulfs the pathogen
- The pathogen is stored in the phagocytic vacuole where a lysosome binds
- Lysozyme enzymes them break it down
- Macrophage then becomes and A.P.C

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3
Q

Specific Immune Response

A

This response is specific and has specific cells

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4
Q

How do phagocytes activate T cells?

A

T cells are covered in receptors specific to certain antigens. -
These bind to antigens on the A.P.C (Macrophage)
This binding activates the T cell, it divides into clones
- Clones :
- T helper cell: Release substances to activate B cells, T killer and macrophages
- T Killer: Attach to antigens and kill the infected cell
- T memory: Remember and recognise the specific antigens

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5
Q

How do T cells activate B cells?

A

B cells are covered in proteins called antibodies

  • Antibodies bind to specific antigens to form Antibody-Antigen complex.
  • The binding along with substances from T cells activate B cells
  • The B cell divide by mitosis into plasma cells( B effector) and B memory cells
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6
Q

Antibodies

A

Plasma cells secrete antibodies specific to an antigen

  • made from 4 polypeptide chains 2 heavy and 2 light
  • Variable region: Form the antigen binding site
  • Hinge region: Allows flexibility during binding
  • Constant region: Allows binding to receptors on immune cells
  • Disulphide bridges: Hold the chains together
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7
Q

How do antibodies clear infection?

A

1) Agglutination: Each antibody has two binding sites so an antibody can bind to two pathogens at once. Pathogens clump and can be engulfed by a phagocyte all at once
2) Neutralise Toxins: Antibodies bind to toxins produced by a pathogen. The toxins, therefore, are neutralised.
3) Prevent pathogen binding to cells: Antibodies bind to antigens on pathogens blocking the surface receptors of the pathogen so they cannot bind to cells.

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8
Q

The membrane or secreted antibodies

A

Antibodies can be bound or secreted

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9
Q

mRNA modification before Translation

A
  • Genes contain sections that do not code for amino acids
  • These are called Introns
  • The sections that do code for amino acids are Exons
  • During transcription Introns and Exons are copied
  • This is called Pre-mRNA
  • Introns are then removed by splicing. This is a post-transcriptional change
  • Sometimes some exons are removed to form different mRNA strands.
  • This means more than one amino acid sequence is formed and so more than one protein can be produced from one gene
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10
Q

Degenerate code and Universal code

A

The genetic code is degenerate and universal There is more than one codon for once amino acid. Stop codons do not have anticodons for them.

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11
Q

Immunity

A

This is the body’s defence against disease

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12
Q

Memory cell production

A
  • When a pathogen enters the first time the primary response is triggered.
  • This is slow because B cells haven’t made specific antibodies for the pathogen
  • When enough antibodies are made the infection will be overcome
  • T and B cells produce memory cells that remain in the body for a long time
  • When the pathogen enters for a second time the secondary response is faster and stronger as Memory cells remember the antigens.
  • This occurs before symptoms show
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13
Q

Active Immunity

A

This is when your immune system makes it’s own antibodies.

  • Active natural: When exposed to a pathogen your body produces antibodies and memory cells
  • Active Artificial: When you are given a vaccine against the pathogen.
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14
Q

Passive Immunity

A

When you are given antibodies made by a different organism

  • Passive Natural: When a baby is given antibodies through milk or placenta
  • Passive Artificial: Injected with other organisms antibodies
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15
Q

Vaccines

A

These contain antigens that stimulate a primary response. They contain a weak or inactive pathogen so no disease is caused

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16
Q

Mechanisms to Evade

A

Pathogens evolve to evade detection by immune system cells.

  • HIV MECHANISMS:
  • HIV kills I.S.C that it infects reducing the number of them
  • HIV has a high mutation rate so T memory cells developed for one strand will not work on another form
  • HIV disrupts antigen presentation in infected cells
  • TB MECHANISMS:
  • TB bacteria produce substances that prevent lysosome fusing with the vacuole
  • Bacteria are not broken down and can reproduce
  • TB also disrupts antigen presentation
17
Q

Antibiotics

A

A chemical that kills or inhibits the growth of microorganisms

18
Q

Bacteriocidal antibiotics

A

These kill bacteria

19
Q

Bacteriostatic antibiotics

A

These inhibit the growth of bacteria

20
Q

Why do antibiotics only work on bacteria?

A

Antibiotics affect the bacterial cell wall and Viruses do not have cell walls. Also, viruses replicate in host cells whereas bacteria does not and so antibiotics can destroy bacteria.

21
Q

Antibiotics inhibit bacterial mechanisms

A
  • Inhibit enzymes needed for specific cell wall bonds, can cause incorrect cell wall development
  • Inhibit protein synthesis as they bind to ribosomes so they stop metabolic processes.
22
Q

Broad Vs Narrow spectrum antibiotics

A

Broad:
- Destroy a wide range of bacteria even good bacteria
Narrow:
- Target specific pathogens and bacteria

23
Q

Investigate the effect of antibiotics

A

1) Transfer bacteria onto agar (bacterial lawn)
2) Soak paper discs in different antibiotics
3) Use sterile forceps and antiseptic techniques
4) Place discs onto agar with equal spacing and add control disc
5) Incubate for 25 for 24-48hrs
6) Measure the zone of inhibition and the larger the more successful the antibiotic is

24
Q

Hospital Acquired Infection

A

These are infections caught whilst a patient is being treated in hospital

25
Q

How are HIA’s transmitted?

A
  • Hospital staff and visitors not washing hands
  • Coughing or sneezing not contained
  • Unsterile equipment and surfaces
26
Q

Why are people in the hospital more likely to get HIA’s?

A

People in the hospital already have a weakened immune system and are close to other ill people and so are more likely to catch another infection

27
Q

Codes of Practice to prevent HAI’s

A
  • Always wash hands
  • Equipment and surfaces always sterile
  • People with HAI’s must be isolated to stop spreading.
28
Q

HAI’s can become resistant

A

Some HAI’s that are caused by resistant bacteria are difficult to treat.

  • These are more common as antibiotics are so widely used they evolve to become immune.
  • They evade antibiotics
29
Q

Codes of practice to treat resistant HAI’s

A
  • Use narrow spectrum antibiotics
  • Only prescribe antibiotics when you need to
  • Rotate and finish the full set of antibiotics
30
Q

HIV( Human Immunodeficiency Virus )

A

HIV infects and destroys T helper cells.

- It spreads via infected bodily fluids and can infect damaged tissues or mucosal surfaces

31
Q

How does HIV replicate?

A
  • HIV can only replicate in a host cell
  • It does not have enzymes or ribosomes of its own to replicate without a host

1) Attachment protein attaches to host cell
2) Capsid releases RNA into cells cytoplasm
3) Reverse Transcriptase makes complementary DNA from a viral RNA template
4) Double-stranded DNA inserted into the human DNA
5) Host cell enzymes make viral proteins which assemble into new viruses.

32
Q

HIV causes AIDS:

A

HIV eventually leads to AIDS (Acquired immune deficiency syndrome)

  • AIDS is developed when the immune system deteriorates
  • People with AIDS develop opportunistic infections due to a weakened immune system
  • Initial symptoms of AIDS include Minor infections.
  • Patients become susceptible to things like TB
33
Q

Mycobacterium Tuberculosis

A

This bacterium causes TB. The infection occurs when small droplets containing the bacterium are inhaled

34
Q

How does TB replicate?

A
  • Inside the lungs, the bacterium is taken up by a phagocyte
  • They then replicate inside the phagocyte
35
Q

Dormant TB

A

Most people do not develop TB straight away
The bacteria is dormant and no symptoms occur
Later the bacteria becomes activated causing TB
- TB can cause damage to lung cells and inflammation.
- This can lead to death and can spread to other body parts.

Biology Unit 4 (7 decks)

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