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Biomedical Science Year 1 > Microbiology and Immunology > Flashcards

Microbiology and Immunology Flashcards

1
Q

What is immunity?

A

The ability of an organism to resist a particular infection by a pathogen by the action of specialised cells or molecules

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2
Q

What are the 2 types of immunity?

A

Innate and acquired/adaptive

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3
Q

Characteristics of innate immunity

A

-Present at birth
-Cells patrol for infection
-Uses simple recognition systems (receptors) that identify common pathogen structures or ‘danger’
-Rapid responses (minutes)
-Many cell types involved
-Limited capacity

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4
Q

Characteristics of acquired immunity

A

-Not present at birth needs to be ‘acquired’
-Very sophisticated, highly specific pathogen recognition (receptors)
-Learnt from invading organisms
-Slower response (days)
-Highly specialised cells - generates ‘memory’

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5
Q

What is the goal of the immune system?

A

-To clear/kill potential pathogens in a controlled and efficient process
-With limited pathology to the host (self)
-After appropriate duration, return to homeostasis
-Confer future protection against same pathogen
-To check for non-healthy cells

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6
Q

Factors affecting immunity

A

-General health
-Infection
-Nutrition
-Environmental conditions
-Microbiome
-Pregnancy
-Genetics
-Exams (stress)

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7
Q

What is a vaccine?

A

A substance used to stimulate the production of immunity against one or several diseases (without inducing the disease). It is prepared from either the causative agent of a disease, its products, or a synthetic substitute

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8
Q

What can immunisation protect?

A

-The individual
-The population: disease declines if majority of population is immune

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9
Q

Why may it be difficult for a vaccine to be developed?

A

Complex pathogens, requires understanding of pathogen’s life cycle and immune responses to develop new vaccines, clinical trials are very expensive and time-consuming

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10
Q

What are the 4 types of vaccines?

A

-Live
-Killed (inactive/attentuated)
-Subunits
-Nucleic acid

Type of response needed/vaccine used is organism dependent

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11
Q

Why are bacteria important?

A

-Abundant and inhabit every conceivable niche on earth
-Service many important planetary cycles
-Immensely important in health, disease, food and technology
-Often used in human health research

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12
Q

What are microbiota?

A

Microbial organisms living around us that are not part of our own bodies

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13
Q

What is the microbiome?

A

The genes harboured by the microbiota

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14
Q

Characteristics of bacterial cell well

A

-Important for protection against osmotic and environmental stresses, defines shape, helps with uniform cell division
-Target for immune diseases
-Target for many antibiotics

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15
Q

Advantages of green fluorescent protein

A

-Revolutionary method
-Genetic manipulation to make a protein-GFP fusion
-Enables live cell, time lapse imaging
-Many colour variants, simultaneous visualisation of different proteins

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16
Q

Disadvantages of green fluorescent protein

A

Many fusion proteins malfunction and localisation may be misleading

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17
Q

What is proteinaceous S-layer?

A

-Many bacteria and archea have one
-Outermost layer of the cell envelope
-Crystalline lattice of a single protein
-Protective, selective sieve
-Often lost in lab strains

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18
Q

What is a capsule?

A

-Usually polysaccharide
-Sometimes covalently attached to the wall
-Important in biofilms
-Can be immunogenic
-Can help in avoidance of immune responses

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19
Q

What are pili and fimbriae?

A

-Surface appendages
-Protein polymers
-Attachment and adhesion
-Important in pathogenesis
-Immunogenic
-Support gene transfer by conjugation
-Twitching motility
-Huge range of varied classes of appendage
-Pili are usually longer than fimbriae

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20
Q

What is the flagella?

A

-Incredible rotary motor
-Biological nanomachine
-Rotation and helical structure generate movement
-Chemotaxis gives directionality
-Random biased walk

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21
Q

What are endospores?

A

-Triggered by starvation
-Incredibly resistant
-Heat, solvent, lysozyme etc
-Remain dormant for centuries
-Germinate when favourable conditions occur

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22
Q

What are biofilms?

A

-Communities, often multiple species together
-Held together by a matrix
-Cells often differentiate

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23
Q

Difference between gram negative and gram positive?

A

Gram negative bacteria have an extra layer - the outer membrane

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24
Q

What is growth (bacteria)?

A

An increase in the number of cells

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25
What is generation time (bacteria)?
The time needed for one cell to divide and form two cells
26
Describe the proliferation of bacteria?
-In the right conditions, bacteria grow exponentially -No. of cells doubles at constant time intervals -Eventually nutrients become limiting or toxins accumulate
27
What is lag phase?
Cells adjust to new conditions, synthesise required metabolic enzymes and metabolites
28
What is exponential phase?
Optimal growth with regular doubling in cell numbers
29
What is stationary phase?
Growth limited by nutrient depletion or accumulation of toxic metabolites. Rate of new cell production balanced with rate of cell death so no overall growth in the culture
30
What is death phase?
Complex gradual loss of viability but with some cell turnover
31
Ways of measuring bacterial growth
-Plating methods -Turbidity -Direct microscopic counting -Flow cytometry
32
What is the total cell count?
Total number of bacterial cells
33
What is the viable cell count?
Number of living bacterial cells
34
Advantages of plating methods
-Only measures viable cells -Highly sensitive -Growth conditions can be customised so that only species of interest grow
35
Disadvantages of plating methods
-Underestimates for cell in chains of clusters -Number of colonies dependent on growth conditions
36
Advantages of turbidity methods
-Simple and convenient -Non-destructive and can be done continuously
37
Disadvantages of turbidity methods
-Measures all particles, including dead cells -Low sensitivity -Culture turbidity has to be within a certain range to be accurate
38
Advantages of direct counting methods
-Most direct method -Can accommodate clumping and chaining
39
Disadvantages of direct counting methods
-Doesn't discriminate live/dead (but staining methods are available) -Laborious (but can be automated)
40
Advantage of flow cytometry and FACS
Can measure fluorescence at multiple wavelengths
41
Disadvantage of flow cytometry and FACS
Requires the right equipment, reagents and expertise
42
How do bacteria chromosomes replicate?
Bidirectionally from a single fixed origin (oriC) to the terminus (terC)
43
Brief description of binary fission
Cell elongates to twice its length, then splits down the middle
44
Detailed description of binary fission
1. - cell grows - cell structures duplicated - chromosome replicated 2. - daughter chromosomes segregate to different ends of the cell 3. -septum forms at mid cell as Z-ring constricts -new cell poles synthesised as ring constricts 4. -cell division occurs at mid-cell -results in two identical daughter cells
45
Describe chromosome replication
-Replisomes bind oriC -Bidirectional replication of DNA -Chromosomes segregate and cells divide. Each cell has one copy of the chromosome
46
How does the replication conundrum change chromosome replication?
-As DNA is being replicated, more replisomes bind both old and new DNA -Initial replication complete, chromosomes segregate and cells divide
47
What do bacteria need to grow?
Temperate, pH, ionic balance, moisture, nutrients, gas
48
What are the four macronutrients?
Protein, carbohydrates, lipids, nucleic acids
49
Why is g, generation time, useful?
-Compare different bacterial species growing in the same condition -Compare one species grown in different conditions -Show data is statistically significant or not
50
Describe bacterial genomes
Small, usually circular, densely packed
51
What is the impact of genome sequencing?
1. Uncovering new unsampled diversity 2. Changing to how we classify organisms 3. Revolutionise bacterial genetics 4. Infectious disease and epidemiology 5. Metagenomics in health and nutrition 6. Genomics in art
52
What is the pangenome concept?
Different strains of the same species can encode a broad range of different genes
53
Key uses of bacteria
Food, water treatment and bioremediation
54
What is bioremediation?
A process that uses mainly microorganisms, plants, or microbial or plant enzymes to detoxify contaminants in the soil and other environments
55
Advantage of biotechnology
Bacterial cultures grow quickly and easily, input materials often cheap and environmentally friendly whereas chemical synthesis can be difficult, laborious and involve expensive and toxic reagents.
56
What is vitamin B12 used for?
Essential for DNA synthesis, only produced by certain bacteria and archaea
57
What is synthetic biology?
The design and construction of new biological parts, devices, systems, and the re-design of existing, natural biological systems for useful purposes. Wide-ranging definition
58
What does the Lac repressor (lacl) do?
Prevents transcription of lactose utilisation genes unless lactose is present. Lacl is 'off' and lactose is 'on'
59
What is protein engineering?
Adding new functions to proteins or improving current functions. These engineered proteins will change the behaviour of bacteria that express them.
60
What is optogenetics?
Induction of bacterial gene expression in tissue via small molecule signalling Potential therapeutic delivery tool
61
What is temperature-controlled gene expression?
-Proteins engineered to respond to temperature -Gene expression turned on between 40-45 -Circuits dictate colour response of E. coli -Potential applications in temperature triggered therapeutics
62
What is metabolic engineering?
-Gene circuits and engineered proteins can be combined to alter or create new metabolic processes in bacteria -Complex, multi-enzyme cascades -Improve the efficiency of current metabolic processes, or allow bacteria to synthesise new compounds
63
Ways of detecting our microbes
Culturing and DNA/RNA sequencing
64
Advantages and disadvantages of culturomics
Important for culture collections and therapy development but expensive and very labour intensive
65
What is the most densely colonised microbial habitat in nature?
Mammalian intestine
66
What can early microbiota disturbances be linked to?
Allergy, autoimmune conditions, inflammatory bowel diseases, obesity
67
What is colonisation resistance?
Resistance to colonisation by ingested bacteria or inhibition of overgrowth of resident bacteria normally present at low levels within the intestinal tract
68
Microbiota disturbances and disease consequences
Causes; diet, antibiotics, birth mode, infections, genetics Diseases associated; intestinal disease, metabolic disease, immune disease, autoimmune disease
69
What is colonisation?
Growth of a microbe after gaining access to host tissue
70
What is pathogenicity?
Ability of a pathogen to inflict host damage
71
What is virulence?
The degree of pathogenicity of an infecting pathogen
72
Respiratory infection
Bacterial or viral, upper respiratory tract has an abundant microbiome, lower respiratory tract typically devoid of microbes
73
E. coli
Gram -ve, normally present in the mammalian gut Diverse array of pathotypes
74
75
What is bacteraemia?
The presence of bacteria in the bloodstream
76
What is sepsis?
Extreme, system-wide inflammatory response to blood poisoning
77
What is systemic shock?
Systemic drop in blood pressure leading to mass organ failure
78
What is pathogenicity driven by?
Adhesion to epithelial surface or invasion or underlying tissue
79
What is the bacterial capsule?
-Key virulence dominant -Encases the bacterial cell -Provides resistance against immune recognition, phagocytosis and complement killing -Exclude hydrophobic detergents -Important precursor to biofilm formation
80
Fimbrial mediated adhesion
-Filamentous, cell surface protein structures -Capped by sugar binding -Type 1 fimbriae -Similar structures called pili are longer, less abundant and involved in genetic exchange
81
Fimbrial catch-bond theory
Strength of binding dictated by an allosteric switch in the FimH-sugar interaction. Can be chemically inhibited
82
HIV resistance to anti-viral drugs can be combatted using?
Highly active anti-retroviral therapy
83
What is the sexual process where genes are transferred from one bacteria to another?
Conjugation
84
What adhesin at the tip of bacterial type 1 pili binds to the sugar mannose?
FimH
85
What is the term given to microorganisms that thrive at temperatures above 88 degrees Celcius?
Hyperthermophile
86
Define viraemia
An increase in viral concentration in the blood
87
Define multiplicity of infection
The number of infectious virus particles per cell when infecting
88
Which bacterial secretion system translocates its own receptor into the host cell membrane?
T3SS
89
What is the resolution limit of an optical microscope (excluding super resolution modifications)?
200nm
90
What is the Escherichia coli pathogen that causes kidney infection classed as?
Uropathogenic
91
What is the structural form of poliovirus?
Naked iscosahedral
92
Which genera of coronavirus affects both mammals and humans?
Alpha and beta
93
Which genera of coronavirus affects both mammals and avians?
Delta
94
Which genera of coronavirus affects avians?
Gamma
95
Which virus has an enveloped helical structure?
Measles
96
Which virus has a naked helical structure?
Tobacco mosaic virus
97
Which virus has an enveloped icosahedral structure?
Herpes
98
What is the cellular response to HIV?
CD4 cells produce CD8 cytotoxic cells
99
Facultative meaning
Will respire aerobically in present of oxygen, and will switch to anaerobic in absence of oxygen

Biomedical Science Year 1 (8 decks)

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