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A-level Biology > Immunity, forensics and infection > Flashcards

Immunity, forensics and infection Flashcards

1
Q

what is a pathogen?

A

a microorganism that can cause disease

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2
Q

name 3 ways to determine how old a corpse is?

A
  • rigamortis stage
  • presence of species
  • body temperature
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3
Q

what is in the core of a virus?

A

nucleic acid

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4
Q

what is a virion?

A

virus before it enters the host cell

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5
Q

what is a capsid?

A

protien coat of a virus

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6
Q

what surrounds a capsid on a large virus?

A

an envelope

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7
Q

which type of nucleic acid in a virus is more dangerous and why?

A

RNA, as it mutates much more

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8
Q

what do spike protiens do?

A

help the virus to attach to specific receptors on the host cell

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9
Q

how many ways of viral entry are there?

A

2

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10
Q

describe both methods of viral entry?

A
  1. virus injects nucleic acid into cell
  2. plasma membrane of host cell surrounds virus and produces a virus filled vacuole in cytoplasm, the virus bursts out, releasing nucleic acid
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11
Q

what are introns?

A

non-coding regions of DNA, used in DNA profiling

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12
Q

what is satellite DNA?

A

large arrays of repeating, non-coding DNA

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13
Q

what does PCR do?

A

amplifies DNA sample

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14
Q

what 5 things does PCR require?

A
  • target DNA
  • primers
  • DNA polymerase
  • free nucleotides
  • buffer solution
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15
Q

what are the 3 stages of PCR?

A
  • denaturation
  • annealing
  • elongation/extension
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16
Q

describe the PCR stage denaturation?

A

DNA is heated to 95C to break hydrogen bonds

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17
Q

describe the PCR stage annealing?

A

temperature decreased to 50-60C so primers can anneal to the ends of single stranded DNA

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18
Q

describe the PCR stage elongation/extension?

A

temperature increased to 72C for 1 minute, this is the optimum temperature to build complementary DNA strands

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19
Q

name 4 features of bacteria?

A
  • no membrane bound organelles
  • no nucleus
  • genetic material in cytoplasm
  • cell wall + membrane
  • ribosomes
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20
Q

what do primary defences do?

A

stop pathogens entering the body

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21
Q

are primary defences specific?

A

no

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22
Q

name 4 primary defences?

A
  • stomach acid
  • gut flora
  • inflamation
  • mucus
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23
Q

how does inflamation stop pathogens?

A

vasodilation increases permeability of blood vessels, so more white blood cells can enter

24
Q

name 3 ways the skin is adapted as a primary defence?

A
  • strengthened by keratin
  • covered by flora
  • antimicrobial secretions
25
Q

where can tuberculosis affect?

A

mainly lungs, can be kidney spine and brain

26
Q

what type of phagocyte engulf tuberculosis bacteria?

A

macrophage

27
Q

how can tuberculosis bacteria survive macrophages?

A
  • overpower and encase macrophage in tubercles
  • stops formation of lysosomes
28
Q

what are the 3 stages of tuberculosis infection?

A
  • primary infection
  • latent infection
  • active disease
29
Q

is HIV RNA or DNA?

A

RNA

30
Q

describe the 4 stages of HIV replication?

A
  • Virus enters T helper cells by attaching to a CD4 receptor
  • reverse transcriptase enzyme produces a complementary RNA strand
  • virus uses host cells enzymes to make new viral components
  • Host cell lyses, viruses enter the blood, cycle repeats
31
Q

name the 3 stages of HIV infection?

A

1 - accute HIV syndrome
2 - Chronic or asymptomatic stage
3 - advanced AIDS

32
Q

how does HIV avoid antibodies?

A
  • frequently mutates, to change antibodies
  • uses host cell plasma membranes to hide antigens
33
Q

what is the lymphatic system responsible for?

A

complex transport of immune cells

34
Q

name the 2 types of phagocyte?

A
  • neutrophyls
  • macrophages
35
Q

name 3 features of neutrophylls?

A
  • most common phagocyte
  • made in bone marrow
  • short acting, for immediate response
36
Q

name 3 features of macrophages?

A
  • biggest phagocyte
  • made in bone marrow
  • adaptive, specific immune response
37
Q

name the 5 stages of phagocytosis?

A

1 - detects pathogen by unique antigen and recognises by its pathogen recognition receptors on cell membrane
2 - phagocyte activates, pathogen is covered in opsinins, helps to bind
3 - engulfs, encases in phagosome
4 - phagosome fuses with lysosome, lysozyme breaks down pathogen
5 - phagocyte absorbs products, some products are discarded, some are used in the antigen presentation process to activate T-helper cells

38
Q

define antibody?

A

glycoprotien with specific antigen binding site

39
Q

name 2 ways antibodies kill pathogens?

A
  • agglutination
  • neutralising the toxins they produce
40
Q

where do B cells form?

A

bone marrow

41
Q

where do T cells form?

A

thymus

42
Q

what are the 2 specific immune responses?

A
  • cell mediated immunity
  • humoral immunity
43
Q

what type of pathogen does cell mediated immunity mainly affect?

A

viruses

44
Q

describe the 4 steps of the cell mediated response?

A

1) Macrophages engulf and digest pathogens, presenting their antigens
2) Specific T helper cells with complementary receptors bind
3) T helper cell produces interloukins
4) Cloned T cells may become T killer, T memory or T helper cells

45
Q

define antigen?

A

specific protiens on every cells surface

46
Q

describe the 4 steps of the humoral response?

A

1) T helper cells bind to antigens on presenting b cells
2) T helper cells produce interloukins
3) B cells divide rapidly into plasma and memory cells
4) Plasma cells produce antibodies to bind to and kill pathogens

47
Q

what type of pathogen does the humoral response affect?

A

bacteria and fungal

48
Q

what happens after a B cell engulfs a pathogen?

A

presents antigens, becoming an antigen presenting cell

49
Q

what are the 2 types of antibiotics?

A
  • bactericidal
  • bacteriostatic
50
Q

what do bactericidal antibiotics do?

A

kill bacteria

51
Q

what do bacteriostatic antibiotics do?

A

slow bacterial growth and reproduction

52
Q

name 4 ways antibiotics can affect bacteria?

A
  • inhibit cell wall synthesis
  • inhibit DNA synthesis
  • disrupt cell membrane
  • disrupt protien synthesis
  • inhibit metabolic enzymes
53
Q

what is MRSA?

A

causes wound infections

54
Q

what is clostridium difficile?

A
  • infects digestive system
  • when gut flora is killed by antibiotics, it can colonise
55
Q

name 3 ways hospitals prevent superbugs?

A
  • hand hygiene
  • isolations
  • stricter prescriptions
56
Q
A

A-level Biology (6 decks)

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