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biology > C3.2 - defence against disease > Flashcards

C3.2 - defence against disease Flashcards

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1
Q

conjugation

A

transfer of DNA from a doner to recipient bacterial cell by direct contact

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2
Q

opportunistic infection

A

infections that occur more often or more severely with people that have weakened immune systems

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3
Q

plasmid

A

small ring of DNA found in prokaryotic cells

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4
Q

pragmatic

A

a mindset that is realistic and is based on practical considerations

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5
Q

pathogen

A

a disease-causing organism
- viruses, bacteria, fungi and protists

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6
Q

how does the skin act as a primary defence against infection?

A
  • physical and chemical barrier
  • defends outer body surface
  • never ciliated
  • produces fatty acids and lactic acid to kill pathogens
  • surface cells tend to be dead
  • thick and strong
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7
Q

how does the mucous membrane act as a primary defence against infection?

A
  • physical and chemical barrier
  • sometimes ciliated to move mucus away
  • defends tubes leading to the outside
  • produces mucus to trap pathogens
  • surface cells are alive
  • thin and weak
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8
Q

what is the role of blood clotting?

A

prevents pathogen from entering the body through damage to the skin

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9
Q

what is the process of blood clotting?

A
  1. platelets detect skin or blood vessel damage
  2. platelets release clotting factors which start a chain or reactions (involving vitamins and proteins)
  3. prothrombin is activated to thrombin (protease)
  4. thrombin converts fibrinogen to fibrin
  5. fibrin fibres form a mesh network that traps platelets and erythrocytes
  6. clot forms and seals the wound
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10
Q

innate immune system

A

responds to broad categories of pathogen, identified as non-self
- doesn’t change during an organisms life
- involves phagocytes

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11
Q

adaptive immune system

A
  • responds in a specific way to particular pathogens via antibody production
  • builds up a memory to make immune response more effective
  • involves a range of lymphocytes
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12
Q

leucocytes

A

white blood cells

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13
Q

phagocytes

A

white blood cells that engulf pathogens

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14
Q

lymphocytes

A

white blood cells that produce antibodies to provide adaptive immunity
- circulate in the blood and are contained in lymph nodes
- make a specific type of antibody to bind to a specific antigen

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15
Q

what are the 2 types of phagocytes?

A

neutraphils - destroys pathogens (innate immune system)
macrophages - pathogen detection and sends signals to the rest of the body (links innate and adaptive immune system)

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16
Q

what are the types of lymphocytes?

A

helper T cells - pathogen detection (adaptive immune system)
B cells:
plasma cells - antibody production (adaptive immune system)
memory cells - provide long term immunity (adaptive immune system)

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17
Q

what is the process of phagocytosis?

A
  1. phagocytes detect chemical signals released by pathogens
  2. phagocytes leave the blood and use amoeboid movement to move to the site of infection
    - leave the blood by squeezing between capillary cells
  3. phagocytes recognise pathogens by binding to them
  4. phagocytes engulf and ingest the pathogen by endocytosis
  5. enzymes in the phagocyte’s lysosomes digest the pathogen
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18
Q

what is the role, structure and location of antigens?

A

recognition molecules that trigger antibody production
- each pathogen has a specific antigen that allows it to be recognised by cell receptors
- located on outer surfaces
- glycoproteins or proteins

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19
Q

what is the impact of antigens on the surface of erythrocytes if transfused into a person with a different blood group?

A
  • antigens may stimulate antibody production = cause clumping of the blood cells (agglutination)
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20
Q

how can the presence or absence of antigens determine our blood group?

A

A = A antigens
B = B antigens
AB = both A and B antigens
O = neither A or B antigens

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21
Q

Rhesus (Rh)

A

blood type involving Rh protein
+ = Rh antigens
- = no Rh antigens

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22
Q

what is needed for a blood transfusion to be successful?

A

must not receive a protein that they do not have already
A- = cannot receive B-
A- = cannot receive A+
AB+ = universal recipient
O- = universal doner

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23
Q

clonal selection

A

to identify which T lymphocytes and B lymphocytes are able to cause production of antibodies that will bind to a specific antigen

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24
Q

what is the process of antibody production?

A
  1. macrophages engulf the pathogen, digest it and present its antigen
  2. helper T cells are activated by binding to a specific antigen
  3. activated helper T cells activate the corresponding B cells only if it is directly binding to the antigen
  4. activated B cells repeatedly divide by mitosis to produce large numbers of clones
  5. B cells differentiate to form memory cells (provide immunity) and plasma cells (produce and secrete the same antibody)
  6. antibody production lasts for several days until all the antigens are destroyed
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25
Q

clonal expansion

A

to provide sufficient quantities of an antibody, activated B cells divide repeatedly by mitosis to produce a large number of clones

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26
Q

what do antibodies do and how long does it last for?

A
  • bind to the specific antigen on the pathogen surface and destroy the pathogen
  • lasts for several days during which all antigens and therefore pathogens are destroyed
27
Q

antigen presentation

A

allows the innate immune system to trigger an adaptive response

28
Q

differentiation

A

produces plasma cells and memory cells

29
Q

immunity

A

ability to eliminate an infectious disease from the body, destroying the pathogen before it causes symptoms

30
Q

what causes immunity?

A

consequence of retaining memory cells - faster adaptive immune response to a pathogen if previously infected

31
Q

what is the difference of antibody production in the primary and secondary immune response?

A
  • faster = no clonal selection
  • more antibodies = memory cells rapidly reproduce to from plasma cells
32
Q

in what context would a second infection by the same pathogen cause a primary response?

A

mutation

33
Q

vaccination

A

stimulate the development of immunity to a specific pathogen by acting as the organisms first exposure without causing the disease

34
Q

what would be found in a vaccine?

A
  • dead or weakened forms of the pathogen
  • antigens or nucleic acids (DNA or RNA) wih sequences that code for the antigen
35
Q

what is the impact of publishing research on a vaccine during its evaluation stage?

A
  • scientists publish research to allow other scientists to evaluate it
  • media can report on this research which consumers need to be aware of
  • vaccines are tested rigorously and side effects are minimal but not 0
  • distinction between pragmatic truths and certainty is poorly understood
36
Q

how do vaccines work?

A
  1. causes antibody production
  2. memory cells are produced so there is a faster and larger immune response than without the vaccine
  3. booster shots stimulate memory cells, increasing antibody levels
37
Q

how does herd immunity prevent epidemics?

A

members of a population are interdependent in building herd immunity
- if a sufficient percentage of a population are immune, transmission is greatly reduced

38
Q

what is percentage difference and how do you calculate it?

A

when making a comparison between 2 separate objects measured at the same time
PD = (difference/mean) x 100

39
Q

what is percentage change and how do you calculate it?

A

used when determining change in a value over time
PC = ((end-initial) / initial) x 100

40
Q

what is the role of antibody production with regards to vaccinations?

A
  1. vaccine is ingested into the body containing weakened versions of pathogens
  2. each antibody corresponds to a specific antigen
  3. macrophages engulf the pathogen
  4. T-lymphocytes are activated by antigen binding and activate B lymphocytes
  5. B lymphocytes divide by mitosis to form clones of plasma cells which secrete antibodies
  6. B lymphocytes are made into memory cells
  7. booster shots stimulate memory cells which produce more antibodies in a faster response
41
Q

zoonoses

A

infectious diseases that can transfer from other species to humans

42
Q

what are examples of zoonoses?

A
  • tuberculosis = transmitted by cattle and can cause lung issues
  • japanese encephalitis = transmitted by a mosquito bite from a pig or bird and causes comas
  • rabies = transmitted by mammals and causes inflammation of the brain and spinal cord
  • COVID 19 = transmitted by bats and can cause respiratory issues
43
Q

what is the process of immunization?

A
  1. vaccine is injected into the body containing weakened fragments of a pathogen
  2. antibodies are made in response to the antigen as well as memory cells
  3. immunity is due to the presence of appropriate antibodies
  4. active immunity - body makes the antibodies itself
  5. natural immunity - exposure to the pathogen
  6. immunization lasts for a long period of time and a booster shot may be needed.
44
Q

what happens when an incompatible blood transfusion occurs?

A

antibodies cause clumping of blood cells leading to agglutination

45
Q

what determines our blood group?

A
  • presence or absence of 3 antigen proteins
46
Q

why can a person with blood group A- not donate to someone with blood group B-?

A

the recipient does not have the B antigen on their cells, so will agglutinate

47
Q

why can a person with blood group A- not donate to someone with blood group A+?

A

the recipient does not have the Rh antigen on their cells, so agglutination could occur

48
Q

why is AB known as a universal recipient?

A

can receive blood from any blood group as they have all three proteins in their blood so will not agglutinate

49
Q

why is O known as a universal donor?

A

their blood doesn’t contain any of the three proteins that could trigger agglutination

50
Q

HIV

A

human immunodeficiency virus - a retrovirus that converts its RNA genome to DNA when it infects a lymphocyte

51
Q

how can HIV be transmitted?

A

transmitted in body fluids
- breastfeeding / saliva
- from mother to fetus
- use of dirty needles
- blood transfusions
- sexually transmitted

52
Q

how can AIDS be a consequence of HIV?

A

only some lymphocytes (t-helper cells) are infected by HIV and killed as the next generation of viruses destroy the cells
- AIDS causes a progressive reduction in the number of active lymphocytes which limits the ability to produce antibodies and fight opportunistic infections
- T-helper cells activate B-lymphocytes which differentiate to plasma cells to produce antibodies

53
Q

outline the cause, transmission and social implications of AIDS?

A

Cause - AIDS is caused by infection with HIV which is a retrovirus that enters lymphocytes and weakens the immune system, leading to increased chance of opportunistic infections
Transmission - bodily fluids such as saliva, dirty needles and blood transfusions
Social implications - when HIV is not managed, AIDS can develop widely and the cost of treatment can impact the health system and reduce populations and workforce as well as discrimination.

54
Q

antibiotics

A

chemicals that block processes that occur in bacteria but not in eukaryotic cells due to differences in metabolism to kill bacteria without the host

55
Q

why are all antibiotics not effective for all species?

A

due to variations in bacterial metabolism, antibiotics are not effective for treating infections by each species and strain of bacteria

56
Q

why do antibiotics fail to control viral infections?

A

antibiotic have no direct contact on viruses as they are not alive and do not have their own metabolism, but use the host cell’s metabolism, but have no antibiotic targets

57
Q

antibiotic resistance

A

problem resulting from excessive use of antibiotics by doctors or in livestock due to low doses or not finishing the course
- bacterial strains evolve resistance to antibiotics via natural selection

58
Q

how does antibiotic resistance occur?

A
  1. variation exists in a bacterial population with some bacteria being naturally resistant to a particular bacteria
  2. the presence of the antibiotic means there is selection pressure
  3. bacteria without the resistant gene die while those who have the gene reproduce
  4. the offspring inherits the gene for the resistance and the frequency in the bacterial population will increase
  5. overtime the resistant population replace the non-resistant population
59
Q

how can bacteria can resistance to a specific antibody?

A
  • random mutation
  • exchanging plasmids with the resistance gene by conjugation with or between species
60
Q

what does antibiotic resistance involve?

A

bacterial strains evolve resistance to antibiotics by natural selection

61
Q

why is antibiotic resistance harmful?

A

population will be exposed to antibiotic resistance bacteria but will not have the antibiotic to kill the bacteria

62
Q

How can antibiotic resistance be reduced?

A

careful, restricted use of antibiotics to slow the emergence of multiresistant bacteria as less use of antibiotics means less antibiotic resistance evolves in pathogens

63
Q

what is an example of how the technique of searching chemical libraries yielded a new antibiotic?

A

searching chemical libraries to yield new antibiotics
- a computer model used AI to analyse molecular structures of compounds in a few days and link this to particular properties to create an antibiotic (Halicin)
- this was then followed up by testing in mouse which determined that the drug has a broad specificity with many drug-resistant species of bacteria being killed

biology (28 decks)

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