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Biology - Year 2 (Eduqas) > Chapter 14 - Immunology and Disease. > Flashcards

Chapter 14 - Immunology and Disease. Flashcards

1
Q

What bacterium causes Cholera and when can it reproduce?

A

Vibrio cholerae and it can only reproduce when its inside its human host.

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2
Q

What does Endemic mean?

A

Disease occurring frequently, at a predictable rate, in a specific location or population.

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3
Q

How do people become infected with Cholera?

A

They become infected by contaminated food or water.

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4
Q

How does Vibrio cholerae affect the body?

A

It releases a toxin in the small intestine which affect the chloride channel proteins. Water and many important ions aren’t absorbed into the blood stream which causes the patient to have very severe, watery diarrhoea. Causes dehydration.

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5
Q

How can Cholera be prevented?

A

With good hygiene and sanitation. Better sewage treatment, water purification, safe food handling and regular hand washing have all reduced the incidence of cholera. A temporary vaccine is also available.

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6
Q

How is Cholera treated?

A

Two strands- Water and ions replaced by giving patients electrolytes. The bacteria are also treated with antibiotics.

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7
Q

What bacteria causes Tuberculosis?

A

Mycobacterium tuberculosis.

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8
Q

How is TB spread?

A

By aerosol transmission (the inhalation of bacteria-laden droplets from the coughs and sneezes of infected people. It spreads very rapidly in crowded conditions. Increase in TB cases has been linked with HIV.

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9
Q

What are the symptoms of TB and how is it treated?

A

It mainly infects the lungs so patients develop chest pain and they cough up phlegm (often containing blood). Its treated with a long course of antibiotics but tuberculosis has shown some antibiotic resistance. A vaccine can be provided but its only given to those at risk.

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10
Q

What virus causes smallpox?

A

Variola major.

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11
Q

How is the smallpox virus transmitted?

A

It is inhaled or transmitted in saliva or from other bodies if there is close contact with an infected person.

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12
Q

What symptoms does smallpox produce?

A

Causes a rash and then fluid-filled blisters which will cause scars in survivors. People have also suffered from blindness and limb deformities.

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13
Q

How is smallpox prevented and what can be done for infected patients?

A

Prevented by a vaccine which produces a strong immune response. Infected people given fluids, drugs to control the fever and pain and antibiotics but 60% die.

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14
Q

Why are humans immune system not able to provide adequate protection when a new strain of influenza appears?

A

Because this new strain has new proteins on the virus surface which means that a pandemic occurs.

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15
Q

Where is influenza’s surface membrane derived from and what are the proteins that act as antigens?

A

Phospholipid envelope from the host’s cell surface membrane. The two proteins are Haemagglutinin (H) and Neuraminidase (N).

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16
Q

What symptoms does influenza cause and how is it transmitted?

A

Attacks mucous membranes causing sore throat, cough and fever. Transmitted in aerosol transmission. Reduced by regular hand washing and using and discarding tissues.

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17
Q

What is an antigenic type?

A

Different individuals of the same pathogenic species with different surface proteins, generating different antibodies.

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18
Q

What are the two ways of a new antigenic type appearing?

A

Antigenic drift - No proofreading enzymes so each round of replication produces a new mutation.
Antigenic shift - If a cell is infected with different combinations of H and N the separate strands can recombine giving rise to new virus types. These new types can cause epidemics.

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19
Q

What protoctistan causes malaria?

A

Plasmodium.

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20
Q

What kind of mosquitos transmit malaria?

A

Female anopheles mosquito

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21
Q

How is malaria transmitted?

A

The mosquito takes blood from an infected person so they take the plasmodium in the sexually reproducing stage. These then develop into an infective stage which migrate from the mosquitos gut to the salivary glands. When another blood meal is taken, the plasmodium is injected into the human which then travel to the liver and reproduce asexually. Merozoites are then produced which are released into the blood and infect RBC where they undergo more reproduction.

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22
Q

How is malaria treated?

A

Drugs are available but they don’t attack plasmodium when it is inside the cells. There have been many different types as some drug resistance has been seen.

23
Q

How is malaria prevented?

A
  • Sleep under nets.
  • Spray indoor walls with insecticide.
  • Drain/cover stagnant water.
  • Sterilise male mosquitoes.
  • Infecting mosquitoes with bacterium.
24
Q

How do viruses reproduce?

A

They reproduce using the host’s metabolism to copy their own nucleic acid and synthesise new coat protein. They’re released by lysis of the host cell or budding (acquire an envelope from the host’s membrane).

25
Q

What are antibiotics produced by and what’s the difference between broad-spectrum and narrow-spectrum.

A

Produced by fungi.
Broad- affects many different Gram+ and Gram- species.
Narrow- Much more selective.

26
Q

Why do antibiotics not affect viruses?

A

Because viruses do not have cell walls or metabolic pathways.

27
Q

Out of Cholera, TB, Smallpox, Influenza and Malaria, which are Viruses, Which are caused by bacterium and which is caused by protoctistan?

A 
Virus = Smallpox and Influenza.
Bacterium = Cholera and TB.
Protoctistan = Malaria
28
Q

What is the difference between how Bactericidal and Bacteriostatic antibiotics act?

A 
Bactericidal = The antibiotics kill the bacteria e.g. Penicillin which destroys their cell walls. 
Bacteriostatic = They prevent bacterial multiplication but don't cause death (e.g. Tetracycline which inhibits protein synthesis).
29
Q

What forms the bacterial cell wall and what is it made up of?

A

Peptidoglycan (or murein).

It contains polysaccharide and short chains of amino acids.

30
Q

What stain turns Gram + bacteria violet?

A

Crystal violet.

31
Q

Why is Gram - bacteria unaffected by crystal violet and what counter stain can be used?

A

Because it has a layer of lipoprotein and lipopolysaccharide surrounding it (this layer protects the bacteria from antimicrobial agents such as penicillin). Safranin turns them red.

32
Q

How does Penicillin affects Gram + bacteria and some Gram - bacteria?

A

It acts as an enzyme inhibitor, preventing the the condensation reactions that make cross-links between the amino acid side chains and the peptidoglycan molecules. Cell wall is then weakened so the cell lyses.

33
Q

What fungus produces Tetracycline and how does it work on bacteria?

A

Streptomyces produces tetracycline and it inhibits protein synthesis by binding to the 30s subunit of ribosomes and blocks tRNA attachment in the 2nd position.

34
Q

What is Antibiotic resistance?

A

A situation in which a micro-organism that has previously been susceptible to an antibiotic is no longer affected by it.

35
Q

How can antibiotic resistance come about?

A

Every time bacterial DNA replicates, a mutation conferring resistance may arise. Bacteria divide rapidly when conditions are suitable so they have a high mutation rate.

36
Q

What are some examples of the innate, natural barriers that resist infection?

A
  • Skin/Keratin makes it waterproof and collagen makes it tough.
  • Skin flora/outcompete pathogenic strains.
  • Mucus traps spores and cilia bring them back up to be swallowed.
  • If the skin barrier is breached, blood clots and increased blood flow to affected area (increased temp).
  • Lysozyme/in tears, mucus and saliva.
  • Stomach acid.
  • Phagocytic cells engulf microbes.
37
Q

What does ‘Adaptive mean?

A

Means the body produces a specific response to each antigen, so the body is adapting.

38
Q

What does the Humoral response result in?

A

The production of antibodies.

39
Q

Where do B lymphocytes mature?

A

In the spleen and lymph nodes.

40
Q

What are the two types of cells that B lymphocytes produce when a foreign protein is detected in the blood stream?

A

Plasma cells - release antibodies.

Memory cells - remain dormant in the circulation and then divide in the same antigen is encountered in the future.

41
Q

Why do antibodies have a quaternary structure and what are the components held together by?

A

Because they are glycoprotein molecules made up of four polypeptides which are held together by disulphide bonds.

42
Q

What is it called when microbes with antigens on their surface are clumped together?

A

They agglutinate.

43
Q

The cell-mediated response refers to the activation of what?

A

Activation of phagocytic cells (B lymphocytes and T lymphocytes.

44
Q

Where are T lymphocytes activated and what are the 3 kinds that can be produced?

A

They are activated in the thymus gland.
-T memory cells - remains dormant and then divide if the same antigen in encountered again.
-Killer T cells - kill pathogenic cells with the antigens (by lysing them).
T helper cells - release chemicals such as cytokines.

45
Q

What to cytokines stimulate?

A
  • Phagocytic cells to engulf pathogens and digest them (macrophages, monocytes and neutrophils).
  • B and T lymphocytes to undergo colonial expansion.
  • B lymphocytes to make antibodies.
46
Q

What is antigen presentation?

A

Where macrophages engulf the foreign antigen/cell/virus and incorporate the antigenic molecules into their own cell membrane.

47
Q

What does the secondary immune response rely on?

A

It relies on memory cells and should protects against an identical antigen, even decades after the original exposure.

48
Q

What is active immunity?

A

Where the body makes its own antibodies, stimulated by either infection or vaccination.

49
Q

What are vaccines?

A

-Antigens isolated from the pathogen.
-Weakened strains of the pathogen.
-Inactive/killed pathogens.
-Inactivated toxins.
These cause the body to produce memory cells so if the person is exposed again, a quick response is produced and no symptoms are shown.

50
Q

What is passive immunity?

A

Where the body receives antibodies produced by another individual e.g. from mother to foetus across the placenta/to the baby in breast milk.

51
Q

Why is the protection given by injected antibodies short lived?

A

Because toe body mounts an immune response against them as they are recognised as being foreign. The individual also won’t have any relevant memory cells.

52
Q

What does it mean if the antigen is highly immunogenic?

A

Means a single dose of the vaccine would cause a strong response from the immune system.

53
Q

When would a vaccination not be medically advised?

A
  • Immunocompromised.
  • Taking chemotherapy.
  • Very old/ill.
  • Living with HIV/AIDS.
54
Q

Why may some people not chose to have vaccinations?

A
  • Religious objections.
  • Preference for alternative/natural medicines.
  • Safety fears.
  • Mistrust of pharmaceutical companies.

Biology - Year 2 (Eduqas) (14 decks)

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