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FOM 1 > Week 5 > Flashcards

Week 5 Flashcards

1
Q

What are protozoa?

A

Single celled animals

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2
Q

Are fungi eukaryotes or prokaryotes?

A

Eukaryotes

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3
Q

What are some of the main differences between eukaryotes and prokaryotes?

A

Prokaryotes tend to be smaller
Prokaryotes are relatively simple and tend to be single celled
Prokaryotes have single circular chromosomes and rarely have introns

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4
Q

What type of ribosome is found in a eukaryotic and prokaryotic cell?

A

Eukaryotic - 80s
Prokaryotic - 70s

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5
Q

What type of organism may a peptidoglycan cell wall be found in?

A

Prokaryotic

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6
Q

How is energy generated across the cytoplasmic membrane?

A

Electrons are released from the cytoplasm, and pass through a series of electron receptors in the membrane. This creates a positive charge and proton gradient across the membrane which can be used by ATP synthase for energy.

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7
Q

Where would a nucleoid be found?

A

Prokaryotic cells

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8
Q

Does the nucleoid have a nuclear membrane?

A

No

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9
Q

What are the repeated sugar chains in a peptidoglycan cell wall?

A

NAM
NAG

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10
Q

What cross link the sugar chains in peptidoglycan cells walls?

A

Peptide side bridges of 5 amino acids

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11
Q

What organisms have multiple layers of peptidoglycan cell wall?

A

Gram +ve

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12
Q

Describe the cell wall in a Gram -ve organism.

A

Relatively small peptidoglycan layer often decorated with LPS.

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13
Q

What type of organism will likely have a second membrane and what purpose can this serve?

A

Gram -ve
Acts as another barrier and creates a periplasmic space where reactions can occur

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14
Q

What does LPS stand for?

A

Lipopolysaccharide

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15
Q

What purpose to LPS serve

A

Structural role
Immunostimulatory
Linked to sepsis and septic shock

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16
Q

What purpose can flagella serve?

A

Rotary motor allowing motility

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17
Q

What are the four classic growth stages of bacteria?

A

Lag phase
Exponential phase
Stationary phase
Decline phase

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18
Q

What sources of nutrition are needed for prokaryotic growth?

A

C
O
H
N
Inorganic salts - P, S, K, Mg, Ca, Fe
Trace elements - Zn, Cu, Mn, Ni, Mo
Vitamins

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18
Q

What temperature is ideal for psychrophiles?

A

Low

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18
Q

What temperature is ideal for thermophiles?

A

High

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19
Q

What temperature is ideal for mesophiles?

A

Body temp

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20
Q

What are the four themes of microorganism classification?

A

Appearance
Growth requirements
Enzyme/metabolic tests
Molecular tests

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21
Q

What are the common shapes seen in bacteria?

A

Cocci
Bacilli
Spiral-shaped

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22
Q

What are the types of cocci structure?

A

Individual or attached - Diplococci
Division in one plain to produce chains
Division in three plains to produce clumps

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23
Q

Do cocci tend to be Gram +ve or -ve?

A

Gram +ve

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24
Q

What structures can bacilli be found in?

A

Individual
Chains

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25
Q

When do bacilli tend to be gram +ve and gram -ve?

A

In chains tend to be Gram +ve
In individual tend to be Gram -ve

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26
Q

Describe fusiform bacteria.

A

Long slender rods

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27
Q

Are curved rod bacteria gram +ve or gram -ve?

A

Gram -ve

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28
Q

What types of spiral-shaped bacterial can be found?

A

Rigid spiral
Flexible spiral

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29
Q

In a gram stain what type stains darker?

A

Gram +ve

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30
Q

Name an organism that does not stain well with Gram staining?

A

TB

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31
Q

What are aerobic bacteria?

A

Grow in oxygen/air

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32
Q

What are obligate aerobe bacteria?

A

Require oxygen in laboratory conditions

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33
Q

What are obligate anaerobe bacteria?

A

Killed by oxygen

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34
Q

What are facultative anaerobe bacteria?

A

Can tolerate oxygen but use anaerobic energy production

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35
Q

What is selective media?

A

Selects for the growth of specific prokaryotes

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36
Q

What is differential media?

A

Visible changes in colonies facilitating identification due to incorporation of chemicals in media

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37
Q

What characteristics may be seen in a colony?

A

Form
Elevation
Margins
Size
Colour

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38
Q

Name a Beta haemolytic bacteria?

A

Group A streptococci

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39
Q

What type of haemolysis is partial, complete and no haemolysis.

A

Alpha - Partial
Beta - Complete
Gamma - None

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40
Q

How do serological tests help identify microorganisms?

A

Detect presence of specific IgM antibody to virus/microbe

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41
Q

What is 16sRNA

A

Ribosome that is different within bacteria compared with humans
Multiple types that can be carried by organisms

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42
Q

What can an immune under-reaction lead to?

A

Infection
Cancer

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43
Q

What can an immune over-reaction lead to?

A

Autoimmune problem
Allergic reaction

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44
Q

What are the constitutive barriers to infection?

A

Skin
Mucus
Commensal bacteria

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45
Q

What can be found in mucus to support its function?

A

Secretory IgA
Lysozyme
Defensins
Antimicrobial peptides
Lactoferrin - Starves of Fe

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46
Q

What is the difference between innate and adaptive immunity?

A

Innate immunity is continuously present from birth, the same generic response occurs to many microbial species.
Adaptive immunity is induced by the presence of foreign materials and generates a unique response to each individual pathogen.

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47
Q

What is the time period for innate and acquired immunity?

A

Innate - 0-96 hours
Adaptive - >96 hours

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48
Q

What are the immune cells of natural immunity?

A

Macrophages
Mast cells
NK cells
Neutrophils

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49
Q

What are mast cells?

A

Large tissue-resident cells
Granular
Pro inflammatory
Parasitic killing mechanisms

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50
Q

What are macrophages?

A

Large phagocytic cells
Important source of cytokines
Also promote tissue repair and limit acute inflammatory responses

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51
Q

What are natural killer cells?

A

Large granular cells
Detect and kill tumour cells and virally-infected cells

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52
Q

What are PAMPs?

A

Pathogen Associated Molecular Patterns
Signature molecules not found on human cells

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53
Q

What are PRRs?

A

Pattern Recognition Receptors
Receptors for PAMPs found on the cell surface and in the cytosol to detect pathogens

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54
Q

Describe phagocytosis stages.

A

PRRs are expressed on macrophages and neutrophils.
Binding to PAMPs signals phagocytic cup formation.
The cup extends around the target and forms a phagosome.
The phagosome fuses with lysosomes forming a phagolysosome to kill the pathogen.
Debris are released into extracellular fluid.
Pathogen derived peptides are expressed on cell surface receptors.
Pro-inflammatory mediators are released.

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55
Q

What is opsonisation?

A

The coating of pathogens by soluble factors to enhance phagocytosis

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56
Q

Give some examples of opsonins.

A

C3b
CRP
IgG/IgM

57
Q

What are the 3 ways neutrophils can kill?

A

Phagocytosis
Degranulation
NETs

58
Q

What are the 2 ways neutrophils can carry out phagocytosis?

A

Phagolysosomal killing
ROS-dependent killing

59
Q

Describe degranulation.

A

Release of antibacterial proteins from neutrophil granules directly in the extracellular milieu

60
Q

Describe neutrophil killing by NETs.

A

Neutrophil suicide to immobilise pathogens to prevent spreading and facilitate subsequent phagocytosis.

61
Q

What are NETs composed of?

A

Genomic DNA
Histones
Granular proteins
Enzymes

62
Q

What is released by virally infected cells?

A

Cytokines called interferons. Interferon alpha and beta signal neighbouring cells.

63
Q

What do NK cells respond to?

A

MHC class 1 molecules

64
Q

What happens when NK cells are activated?

A

They release perforin proteins that insert into the membrane of a target cell; forming a pore causing osmotic lysis of the target cell.

65
Q

What is the role of CRP

A

Prime certain bacteria for destruction by the complement system and phagocytes. Functions as an opsonin.

66
Q

What is the first acute phase protein of the complement system?

A

C3

67
Q

What are the 3 pathways by which C3 can be cleaved?

A

Classical pathway
Mannose-binding lectin pathway
Alternative pathway

68
Q

What is C3 cleaved into to become active?

A

C3a and C3b

69
Q

What type of cells express mannose?

A

Certain bacterial species

70
Q

What enzyme converts C3?

A

C3 convertase.

71
Q

What does active C3b do?

A

Associates with other complement system proteins producing a C5 convertase cleaving C5

72
Q

What do C3a and C5a do?

A

Anaphylatoxins - Promote vascular changes, acute inflammation and leukocyte recruitment

73
Q

What protein in linked to MAC in the complement cascade?

A

C5b

74
Q

How does C3b cause further cleavage?

A

Activates the alternative pathway through amplification loop

75
Q

What are the 2 major categories of T cells?

A

CD4+
CD8+

76
Q

What structures induce an adaptive immune response?

A

Antigens

77
Q

What is an antibody?

A

Any substance that is produced in response to an antigen

78
Q

What is a BCR?

A

B cell receptor, an antibody

79
Q

What are the four polypeptide chains on an antibody?

A

2 x light chain
2 x heavy chain

80
Q

What kind of antigens can be recognised by T cells?

A

Peptide antigens

81
Q

What is a TCR composed of?

A

T cell antigen receptor
Alpha chain and beta chain held together by peptide bonds

82
Q

What presents peptide antigens to TCRs?

A

MHC molecules

83
Q

What are the main differences between class 1 and 2 MHCs?

A

Class one are expressed on all nucleated cells, class two only on professional antigen presenting cells (dendritic, macrophages and B cells)
Class one present to CD8+ and class two present to CD4+

84
Q

Where do lymphocytes develop?

A

Initially bone marrow
T cells mature in the thymus
B cells mature in bone marrow

85
Q

Where do T cells and B cells segregate to in secondary lymphoid tissues?

A

T cell and B cell zones

86
Q

What do stromal cells do in secondary lymphoid tissues?

A

Found in B cell zone and catch and hold antigens to allow B cell activation

87
Q

What cell displays peptides for T cells?

A

Dendritic

88
Q

When activated what do B cells do?

A

Clonally proliferate
Differentiate into effector cells: Plasma and memory B cells

89
Q

What do plasma cells do?

A

Produce and secrete soluble, antigen specific antibodies

90
Q

What do memory B cells do?

A

Long lived cells that circulate the body

91
Q

What is needed to activate a B cell?

A

Antigen binding and co-stimulation

92
Q

What are the first antibodies to be secreted by short-lived plasma cells?

A

IgM

93
Q

What antibody is low affinity but quickly made?

A

IgM

94
Q

What can be the second signal for a B cell with a protein antigen?

A

T helper cells

95
Q

How to B cells present MHC-II molecules?

A

The protein antigen bound to the BCR is internalised by the B cell and degraded, deriving peptides that are presented on the B cell surface in an MHC-II complex

96
Q

Describe the germinal centre reaction?

A

Effector Tfh cells migrate into B cell zone and are re-stimulated by B cells in an antigen-specific manner. They then stimulate the B cell to clonally proliferate and differentiate into long-lived plasma cells that secrete high affinity antibodies.

97
Q

What forms can IgM be found in?

A

Membrane-bound monomeric form
Secreted pentameric form

98
Q

What is agglutination?

A

Action of an antibody when it cross-links multiple antigens producing clumps of antigen

99
Q

What immunoglobulin classes mediate agglutination?

A

IgM and IgG

100
Q

What is the most abundant antibody in normal human serum?

A

IgG

101
Q

What are the functions of IgG?

A

Agglutination
Complement system activation
Foetal immune protection
Neutralisation
Opsonisation
NK cell activation

102
Q

What is the function of IgD?

A

Membrane-bound monomeric form serves as B cell antigen receptor and mediates B cell activation

103
Q

What is the function of IgA?

A

Monomeric form in serum functions in neutralisation
In secretory fluids dimeric form acts in neonatal defence and neutralisation

104
Q

What type of antibody can trigger allergic responses?

A

IgE

105
Q

Where are immature dendritic cells found?

A

Normal non-inflamed tissues

106
Q

What can an activated CD4+ T cell differentiate into?

A

Th1 cells
Th2 cells
Tfh cells
Th17 cells
Regulatory T cells

107
Q

What is Interleukin 2 (IL-2)?

A

T cell growth factor released by activated CD4+ T cells

108
Q

What do Th0 cells do?

A

Induce autocrin/paracrine mediated proliferation of activated CD4+ and activated CD8+ T cells

109
Q

What do effector Th1 cells do?

A

Enter sites of infection/inflammation and are re-activated by infected macrophages. They then secrete pro-inflammatory cytokines to enhance macrophage activating by stimulating production of reactive oxygen species.

110
Q

When does ROS production supported by Th1 T cells help macrophages?

A

In killing pathogens that can evade normal phagolysosomal mechanisms

111
Q

What do effector Tfh cells do?

A

In the B cell zone are re-stimulated by B cells (antigen-specific). When re-activated stimulate B cells to clonally proliferate and differentiate.
This is done by increasing cell surface co-stimulatory molecules and secreting cytokines to further activate the B cell.

112
Q

What are the cells CD8+ T cells differentiate into known as?

A

Cytotoxic T lymphocytes (CTLs)

113
Q

How do CTLs kill infected host cells?

A

Secretion of cytotoxic granules
Expression of Fas ligand

114
Q

What cells contribute to immunological memory?

A

Memory CD4+ T cells
Memory CD8+ T cells
Memory B cells
Long-lived plasma cells

115
Q

What is virulence?

A

The capacity of a microbe to cause damage to the host

116
Q

Name some common protozoan diseases.

A

Malaria
Toxoplasma
Cryptosporidiosis

117
Q

Name common Gram +ve bacteria.

A

Streptococcus spp.
Staphylococcus spp.
Enterococcus spp.
Clostridium

118
Q

Name common gram -ve bacteria

A

Neisseria spp
Escherichia spp
Shigella spp

119
Q

Name some gram -ve cocci and the diseases they cause.

A

Neisseria meningitidis - Commonest cause of bacterial meningitis
Neisseria gonorrhoeae - Causes gonorrhoea

120
Q

What gram -ve bacteria are associated with the GI tract?

A

Commensal - Most E.Coli, enterobacter spp, klebsiella spp.
Pathogens - Salmonella spp, shigella spp, verotoxin producing E. coli

121
Q

What are coliforms?

A

A species of gram -ve bacilli that look like E.coli on Gram film and when cultured on blood agar.

122
Q

When can coliforms become problematic?

A

When they get into a normally sterile site, e.g. UTI

123
Q

What is the first line treatment for infections caused by coliforms?

A

Gentamicin

124
Q

What is sepsis?

A

A host response to severe infection mediated by LPS/endotoxin via host immune system

125
Q

What occurs in sepsis?

A

Small blood vessels become “leaky” and lose fluid into tissues.
Lower blood volume increases HR to maintain oxygenation.
Poor perfusion means blood supply to non essential organs shut down to maintain supply to the brain.
The blood clotting system is activated causing clotting in tiny blood vessels, this uses up all clotting factors increasing haemorrhage risk.

126
Q

What diseases are associated with streptococci A?

A

Streptococcal sore throat (Scarlet fever)
Invasive diseases e.g. necrotising fasciitis
Puerperal sepsis - Infection of pregnant and post natal women

127
Q

What is streptococcus pneumoniae?

A

Gram +ve
Alpha haemolytic
Cocci
Commonest cause of pneumonia

128
Q

What is the most important group of non-haemolytic cocci?

A

Enterococci

129
Q

What is VRE?

A

Vancomycin resistant enterococci

130
Q

Are staphylococci gram +ve or -ve?

A

Gram +ve

131
Q

Name 3 types of staphylococci.

A

S.Aureus
S.Epidermidis
S.Saprophiticus

132
Q

What kind of bacteria is MRSA?

A

S. aureus

133
Q

What bacteria is the most common cause of skin, soft tissue and wound infections?

A

S.Aureus

134
Q

Are clostridioides gram +ve or -ve?

A

Gram +ve

135
Q

What is a viral particle composed of?

A

Nucleic acid genome
Protein capsid
Sometimes a lipid envelope

136
Q

What are the phases of the viral growth cycle?

A

Attachment
Entry
Uncoating
Synthesis of Viral Components
Assembly and Release

137
Q

How do enveloped viruses acquire their envelopes?

A

Budding

138
Q

How do viruses damage the host?

A

Viral factors - Cell lysis, cell-cell fusion, inhibition of host transcription, alteration of host cell cycle
Host factors - Apoptosis, lysis of infected cells by immune cells, inflammation

139
Q

How are viral infections diagnosed?

A

PCR
Antigen testing
Antibody testing

140
Q

What can anti-viral drugs target?

A

Viral nucleic acid polymerases
Viral enzymes involved in nucleic acid replication or protein synthesis
Uncoating
Attachment/entry
Release

141
Q
A

FOM 1 (14 decks)

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