Microbiology Flashcards
(147 cards)
1
Q
Draw a prokaryotic cell
A
Lecture 1
2
Q
What are the 3 shapes of bacteria?
A
Cocci
Rods
Spirals
3
Q
What is an important feature in eukaryotic cells not found in prokaryotic cells?
A
Nuclear envelope
4
Q
What shape is a bacteria chromosome?
A
Singular, circular
5
Q
Where is the chromosome of a bacteria found?
A
Nucleoid
6
Q
What are plasmids?
A
Small, self-replicating DNA molecules found in the cytosol
7
Q
What is a bacteria cell wall made out of?
A
Peptidoglycan
8
Q
What is the purpose of a cell wall
A
Stops the cell from bursting.
Confers cell shape
Provides strength to the cell
9
Q
What is the structure of peptidoglycan?
A
Alternating units of NAG and NAM
For structure, they are linked together with amino acids.
10
Q
What is transpeptidase?
A
Enzyme that cross-links the peptidoglycan chains to form rigid cell walls
11
Q
What cells are dyed purple by the crystal violet and why?
A
Gram positive because they have a thick cell wall
12
Q
Which cells are dyed using the counter stain? And why?
A
Gram-negative because they have a thinner layer of peptidoglycan so doe not hold crystal violet very well
13
Q
How are bacteria capable to moving?
A
Using flagella
14
Q
Ho big are flagella?
A
5-20nm
15
Q
What is chemotaxis?
A
Bacteria moving along a concentration gradient towards a chemical gradeint
16
Q
What is a fimbriae?
A
Structures with adhesive structures on the surfaces of cells
17
Q
Are fimbriae more or less numerous than flagella?
A
More
18
Q
What is a pili?
A
Adherent factor on bacteria that allows them to attach to other bacteria and transfer genetic material to each other
19
Q
What are the 2 types of bacterial adhesive factors?
A
Pili and Fimbriae
20
Q
What is a genetic transfer called?
A
Conjunction
21
Q
What is glycocalyx?
A
Gelatinous polysaccharide/ peptide outer covering which forms a meshwork of fibres
22
Q
What are the two types of glycocalyx?
A
Capsule and slime layer
23
Q
Is a capsule or a slime layer disorganised?
A
Slime layer
24
Q
What is the function of a capsule?
A
Virulence factors (protects from phagocytosis)
Prevents cell from drying up
25
What is a bacterial endopore?
Bacterial spore inside of bacteria
26
WHy do bacterial endospore form?
When there are unfavourable growth conditions so that they can germinate in favourable conditions.
27
What are the stressors that tirgger endospore formation?
Nutrient starvation
High cell density
28
Are bacterial endospores present in gram - or + bacteria?
Positive
29
What is binary fission?
Asexual reproduction for prokaryotes
30
What is the result of binary fission?
2 genetically identical cells
31
How are microorganisms studied?
Thy are cultured
32
What is a closed batch culture system?
A form of cell culturing where microorganisms are put in a closed system with limited amounts of nutrients
33
What are the 4 stages of microbial growth?
Lag, exponential, stationary, and death
34
What happens in the stationary phase of microbial growth?
Cells stop growing and cryptic growth is observed.
35
What happens in the lag phase of microbial growth?
Time required to get biosynthetic reactions running
36
What happens during the exponential phase of microbial growth?
Cells divide and population is growing exponentially
37
What is a determining factor of the length of the lag phase?
History of the inoculum
38
What is cryptic growth?
Dynamic population where organisms survive by consuming other dead cells within the culture
39
What is the death phase of microbial growth?
Equilibrium between growing and dying cells is skewed towards death
40
What are the 3 things required by prokaryotes to multiply?
Carbon source
Energy source
Reducing power
41
what is reducing power for prokayotes?
Carriers of energy/electrons
42
How do prokaryotes harvest energy?
Breaking chemical bonds releases energy which can be captured as ATP.
43
Describe the breakdown and buildup of energy transformation in prokaryotes
Lecture 2
44
What is an auxotroph?
An organism that is unable to synthesise one or more essential growth factors
45
What is a wildtype strain in terms of culture?
Can grow by itseld and has all essential genes
46
What is cross-feeding/Syntrophy?
When one species gain metabolic produces of another species
47
What allows for the survival of auxotrophs?
Cross-feeding.
48
What is a microbiome?
A complete collection of micro-organims and their genes in a specific environment
49
What is microbiotia?
Individual microbial species in a biome
50
What is a culture dependent method?
Reliance of culturing microbes in labs
51
What is a culture independent method?
Relies on nucleic acid based methods.
Sequencing of metabolic profiles to study all microbes in a sample.
52
What are the pros of culture-dependent methods?
Allows access to the phenotype
Can study more than 1 organism
Can manipulate the conditions
53
What are the cons of culture-dependent methods?
Not all organisms can be cultured
Culturing requires precise conditions
Does not match real world contions
54
What are the pros of culture-independent methods?
Allows access to a genotype
Can study many organisms
Shows communities as in nature
55
What are the cons of culture-independent methods?
not easy to manipulate
Expensive and complex
56
Is the cultured or uncultured microbial world greater?
Uncultured
57
What is a population in terms of microbes?
Individual microbial cells of a species
58
What are interactions between populations called?
Communities
59
What is the basis of energy transfer in cells?
RedOx
60
How is the redox reaction shuttled?
Through NADH/NADPH
61
What are the 4 key trophic groups in microorganisms?
Chemoautotrophs
Chemoheterotrophs
Photoautotrophs
Photoheterotrophs
62
What does a photoautotroph do in terms of energy source and carbon source?
Energy source from light
Makes its own carbon
63
What does a heterotroph do in terms of carbon source?
Decomposes/ takes carbon form other sources
64
How do photo microbes avoid competition?
Tuning their antennae to a different wavelength
65
What was the aim of the human microbiome project?
Characterise microbrial communities in multiple human body sites
66
What were the emphasis of the human microbiome?
Oral, skin, vaginal, gut, nasal, and lung
67
How many microbial species are in the human microbiome?
10,000
68
How many bacteria species are in the gut?
500-1,000
69
True or false, the gut bacteria have 50x more genetic diversity than the human genome?
True
70
What are the main 9 things that our microbiome does for us?
Prevents pathogens
Blocks colonisation niches
Competing for nutrients
Modifies environment for virulence factor
Makes environment hostile
Lowers pH
Thickens mucus layer
Upregulate antimicrobial peptides
Primes neutrophils and macrophages
71
What are the 4 dominant bacterial and archaeal groups in our gut microbiome?
Firmicutes
Bacteroidetes
Actinobacteria
Proteobacteria
72
What is a function of the gut microbiome in terms of plants
Gut microbiota can create SCFAs that modulate our metabolisms and can break down cell walls, allowing us to digest plant matter.
73
What is a function of the gut in terms of vitamins?
The gut can synthesise vitamens and modulate immune response
74
What is a functional food?
Food claiming to have a health-promoting property
75
What is a Probiotic?
Live micro-organisms that survive transit through the stomach and may help the gut
76
What is a Prebiotic?
An ingredient that nourishes good bacteria in the large bowel or colon
77
What is the purpose of a prebiotic?
Stimulate the growth of probiotics
78
What is the difference between C. difficile and lactobacillus?
Nothing besides the speed of growth and the presence of accessory genes
79
What is an FMT?
Fecal microbiota transplant which successfully treats CDI (clostridium difficile infection)
80
What are viruses?
Genetically diverse parasitic entities that hijack the molecular resources of the host.
81
What do viruses rely on to multiply?
Biosynthetic machinery of infected cells
82
What is the composition of a virus (3)
Genetic material
Capsid
Envelope of lipids
83
What is the capsid of a virus?
Protein coat that protects the genetic material
84
What is the purpose of an envelope of lipids on a virus?
Surround the protein coat when they are outside of a cell
85
What is a capsid made out of?
Capsomers
86
How can capsids be arranged?
Helical
Icosahedral
Complex
87
Describe the structure of a helical capsid
Capsomers packed tightly together with a twist so that they eventually form a helix. They can rod-like structures
88
Describe the structure of a icosahedral capsid
Lots of axis of symmetry, made up of lots of triangles
89
What shapes could a viral genome be?
Linear
Circular
Segmented
90
What are the 4 possible forms of RNA and DNA?
ssRNA
dsRNA
ssDNA
dsDNA
91
What do viruses infect?
Cells and all forms of life.
Host cells and host organisms
92
What is a bacteriophage?
Viruses that infect and replicate in bacteria
93
What is the lytic cyles of a bacteriophage infection? (6)
1. Attach
2. Penetrate
3. Uncoat
4. Genome replication
5. Assembly
6. Release
94
What is the result of bacteriophage infection?
Many copies of the virus
95
What is the result of viral RNA polymerase copying a gene?
Errors, this allows tracking and leads to new strains.
96
What is the purpose of a spike in a virus?
Attachment and cell entry, major target for neutralising immunity
97
What are the 3 properties of a bacterial genome?
Single, circular
No nuclear membrane
Other DNA molecules can be found known as plasmids.
98
What is horizontal gene transfer?
Gene transfer directly from one organism to another
99
What is vertical gene transfer?
From a parent to an offspring
100
What are the 2 important attributes transferred horizontally by bacteria?
Virulence factors
Antibiotic resistance
101
What is a virulence factor?
Things that help bacteria survive within the host e.g. smooth capsule
102
What are the 3 strategies of horizontal gene transfer?
Transformation
Transduction
Conjugation
103
Describe Transformation in terms of horizontal gene transfer
DNA from dying or dead bacteria and released into the environment. They then enter other bacteria
104
Describe transduction in terms of horizontal gene transfer
Done by a bacteriophage. Tall capsules which can connect to other cell membranes and inject them with genetic material
105
Describe conjugation in terms of horizontal gene transfer
Sex pili between beacteria allowing them to transfer plasmids (DNA)
106
What is an advantage of bacteriophage therapy?
Specific
Occur naturally
Safe
Active against antibiotic resistant bacteria
107
What is a disadvantage of bacteriophage therapy?
Difficult to administer
Not accessible
108
What are the 4 key stages to microbial pathogenesis?
Adherence
Invasion
Replication
Damage to host tissues
109
What are the toxic virulence factors?
Endotoxins
Exotoxin
110
What are the 3 types of exotoxins?
Cytotoxins
Neurotoxins
Enterotoxins
111
What affect does a cytotoxin have?
Complete lysis of red blood cells
112
What affect does a neurotoxin have?
Paralysis
113
What affect does a enterotoxin have?
Severe dystentry
114
What is an exotoxin?
Proteins produced within living bacteria, then released into the surrounding medium
115
What is selective toxicity?
Bacteria taking up different things (selectively), so that medicine can kill viruses and not host cells
116
How discovered Penicillin?
Alexander Fleming
117
How does Penicillin work?
By interfering with the formation of a bacterial cell wall (the peptidoglycan cross bridges)
118
Describe the concept of antibiotic resistance
Proportion of bacteria with a mutant survive and go on to multiply, forming a resistant colony.
119
What is beta lactamase?
Enzyme produced by bacteria to destroy penicillin
120
Can antibiotic resistance be tranferred horizontally?
Yes
121
In what 4 ways can we reduce the development of antibiotic resistance?
Restrict utilization (in agriculture)
Improve diagnostics (more effective treatment)
Identify new targets
Combination therapies
122
What are the 5 stages of an infectious disease?
Incubation Period
Prodromal
Illness
Decline
Convalescence
123
What is the most infectious stage?
Illness
124
What makes Rhinoviruses easy to destroy?
They have a naked capsid
124
Describe the chain of infection (6)
Causative agent
Source
Means of exit
Mode of transmission
portal of entry
Person at risk
125
What is mortality?
Incidence of death within a population
125
What is morbidity?
Incidence of the disease, both fatal and non-fatal cases
126
What is prevalence?
Total number of new and existing cases in a population at a given time
126
What are crude death rates talking about?
Mortality
126
What is incidence?
Number of new cases of a disease over a given time
127
What is an endemic disease?
Disease that is commonly present (baseline) in a community
128
What is a sporadic disease?
Occurs infrequently and irregularly in that location
129
What is an epidemic?
Increase in the number of cases in a particular area
130
What is a pandemic?
An epidemic spread over several countries and continents
131
How much of the world's population is affected by HIV
0.6%
132
How can HIV be treated
Anti-retroviral drugs
133
Do viruses have genomes?
Yes
134
What do you find when you sequence the HIV genome?
That bacteria have phylogenetic trees
135
What explains the tree of HIV sequences?
Infection from multiple viruses
Viruses are changing
136
What are the arguments for virus changing?
For: viruses within a patient are more similar than those between
Against: The same virus can be found in multiple parts of the tree
137
What are the arguments for multiple viruses
For: Multiple sequences
Against: Viruses are more similar within patients
138
What are the two types of HIV sequence changes?
Proximate
Ultimate
139
What kind of virus is HIV?
Lentivirus
140
What kind of genome does HIV Have?
RNA
141
What is reverse transcription
When RNA is turned back into DNA with lots of errors and therefore more variants are formed
142
What parts of the HIV virus makes it prone to selection?
Immune System
Drug regimen
Changes in the receptor
Tropism in tissues
143
