Introduction to Microbiology, Microbiological Concepts & Biochemistry of Microbes Flashcards
1
Q
Which doctor first used handwashing to reduce clinical infection?
A
Ignaz Semmelweis
2
Q
In 1870, which doctor was the first to use antisepsis for surgery?
A
Joseph Lister
3
Q
What is abiogenesis and who disproved that this is how infections start?
A
Abiogenesis is the theory of spontaneous generation. Louis Pasteur was able to disprove this
4
Q
Which scientist first demonstrated that microorganisms caused infectious disease? What two diseases did this person study in the process?
A
Robert Koch demonstrated that microorganisms caused infectious disease through his Germ Theory of Disease (Koch’s Postulates). In the process, he studied anthrax and tuberculosis
5
Q
What is a pure culture?
A
A population of a certain type of cells that are cultured and grow separately from any other type of cell
6
Q
List Koch’s Postulates
A
- The specific causative agent must be found in every case of an infectious disease
- This agent is taken and cultured purely
- A sample is inoculated and transferred to a healthy, susceptible animal. This must cause the same infection.
- The microbe is extracted from the infected animal
7
Q
Three domains of life
A
- Eubacteria
- Archea
- Eucarya
8
Q
Principle members in eubacteria
A
- Gram positive bacteria
- Gram negative bacteria
9
Q
Principle members in eucarya
A
- Protozoa
- Algae
- Fungi
10
Q
What is the main difference between eukaryotic and prokaryotic cells
A
Eukaryotic cells have a nucleus, prokaryotic cells have no nucleus
11
Q
Key features of algae
A
- Eukaryotic
- Photosynthetic
- Unicellular or multicellular
12
Q
Three motility mechanisms for protozoa
A
- Cilia
- Flagella
- Psuedopodia
13
Q
Are fungi eukaryotic or prokaryotic?
A
Eukaryotic
14
Q
How do fungi differ from plants and animals?
A
- Differ from plants as they do not use photosynthesis for energy
- Differ from animals as they have a cell wall
15
Q
Name the two different types of fungi and how they differ to each other
A
Moulds: multicellular, reproduce through spores (sexually and asexually)
Yeasts: unicellular, reproduce by budding (asexually)
16
Q
The cell wall of bacteria contains polysaccharide and peptidoglycan, true or false?
A
True
17
Q
Name the two structures that make up all viruses
A
- Nucleic acid (DNA/RNA)
- A protein coat (capsid)
18
Q
Viruses that infect bacteria
A
Bacteriophages
19
Q
Harmless microorganisms
A
- Around 87% of microorganisms are harmless
- These organisms are helpful and have an important role in the food chain
- e.g. decomposition, nitrogen fixation
20
Q
Opportunistic microorganisms
A
- 10% of microoganisms are opportunistic
- Microbes that are usually harmless but can be pathogenic when placed in different conditions
- e.g. bowel flora that find their way to the bladder
21
Q
Harmful microogranisms
A
- Around 3% of microogranisms are overly harmful
- Can cause disease when present in the body and upon initial contact with a healthy person
- e.g. tapeworm, syphilis
22
Q
Normal flora
A
- Microbes that naturally inhabit surfaces of the human body
23
Q
How can there be a greater microbial load in the body comparing to the number of cells in the body?
A
- Total microbe load >10^3
- Total cells in the body is 10^3
- This is possible as microbes are much smaller than body cells
24
Q
Eukaryotes
A
- Fungi, algae and plants (simple cell wall)
- Protozoa and animals (no cell wall)
- Nucleus and nuclear membrane
- Larger ribosomes
- Larger than prokaryotes (10 - 100 micrometres)
- Reproduce by mitosis/meiosis
25
Prokaryotes
- Archaea and bacteria
- Smaller than eukaryotes (0.1 - 10 micrometres)
- No nuclear membrane or nucleus
- Complex cell wall (with peptidoglycan for bacteria/eubacteria)
- Smaller ribosomes
- Reproduce by binary fission
26
Louis Pasteur
- Disproved theory of spontaneous generation (abiogenesis)
| - Discovered pasteurisation (originally used to prevent spoilage of wine)
27
Robert Koch
- First to study anthrax and tuberculosis
- Koch's postulates
- Contributed to develop staining methods for microbes
28
Robert Hooke
- First person to describe a cell
29
Joseph Lister
- Credited with developing antisepsis for surgery
30
Antoni van Leeuwenhoek
- First to describe bacteria including their shapes
- Reported existence of protozoa two years before
- Bacteria took longer to discover as work was still being done on his microscope, and bacteria are a lot smaller than protozoa
31
Ignaz Semmelweis
- First to use handwashing in clinical practice
32
Bacteria
- Do not have a nuclei
- e.g. Escherichia coli
- Prokaryotic
33
Algae
- Eukaryotes
- Photosynthetic
- Can be unicellular or multicellular
34
Protozoa
- Single celled eukaryotes
35
Fungi
- Have a cell wall
- Not photosynthetic
- Two types: moulds and yeasts
Moulds: multicellular, reproduce sexually and asexually (spores)
Yeasts: unicellular, reproduce asexually (budding)
36
Viruses
- Can only be seen with an electron microscope
| - Cannot reproduce independently, must reproduce inside a host cell
37
Bacteria cell wall composition (gram positive)
- Thick layer of peptidoglycan
| - Teichoic acid and lipoteichoic acid
38
Bacteria cell wall composition (gram negative)
- Thin layer of peptidoglycan
| - Outer membrane contains lipopolysaccharide
39
Glycocalyx
- A gelatinous material which coats the surface of some bacteria
- Capsules and slime
40
Capsules
- Highly organised
- Well attached
- Protect against phagocytosis
- e.g. H. influenzae B
41
Slime
- Not highly organised
- Not well attached
- Helps bacteria to slide on surfaces
- Protect bacteria from drying
- Can be washed off easily
42
Flagella, fimbriae and pili
- Flagella: motility
- Fimbriae: adherence
- Pili: adherence and conjugation (passing DNA from one organism to another)
43
Difference between gram positive and gram negative bacteria
- Differences in the structure of their cell wall
44
Steps of a gram stain
- Spread bacteria across a slide with water
- Heat fix the slide
- Stain with crystal violet (30 sec)
- Stain with iodine (30 sec)
- Discolour with alcohol
- Stain with carbol fuschin (30 sec)
45
How bacteria grow
- Binary fission
- Single cell splits into two identical daughter cells
- Chromosome duplicates, same genetic material in both cells
46
Stages of bacterial growth in broth solution
- Lag phase
- Exponential phase
- Stationary phase
- Death/decline phase
47
Obligate anearobe
- An atmospheric condition
| - Where bacteria is unable to grow in O2 and will only grow in the complete abscence of O2
48
Facultative anearobe
- Atmospheric condition where bacteria is able to grow with or without O2
49
Carboxyphile
- Atmospheric condition where bacteria grows best with an increased concentration of CO2
50
Mesophile
- An organism which grows best in moderate temperatures (optimum 37 degrees)
51
Psychrophile
- An organism which grows best in cold temperatures (optimum 15 degrees)
52
Glycolosis
- Occurs in all cells
- Anaerobic process (no oxygen required)
- Consists of 10 reactions
- For every molecule of glucose, there is a net gain of 2 ATP and 2 molecules of pyruvic acid produced
53
Respiration
- Obligate aerobes and facultative microbes (oxygen required)
Krebs Cycle
- Consists of 8 reactions
- Utilises pyruvic acid
- 2 ATP molecules produced
- CO2 produced
Electron Transport Chain
- Many redox reactions
- Many ATP molecules produced
- H2O produced
54
Fermentation
- Obligate anaerobes and facultative microbes (no oxygen)
- Utilises pyruvic acid
- Not as much ATP produced
- Organic wastes (acids and alcohols) produced
55
Catabolism
- Larger molecules broken down into smaller molecules
56
Anabolism
- Smaller molecules built up into larger molecules
57
Oxidation
- Loss of electrons
58
Reduction
- Gain of electrons
59
What factors (growth & nutritional conditions) need to be considered when culturing bacteria?
- Temperature preferences (whether they grow best in cold temperatures or warm temperatures)
- Atmospheric conditions (whether they can grow with oxygen, without oxygen, with more CO2 etc.)
- Moisture
- pH
- Osmolarity
- Nutrients
60
Microbial biofilm
- Composed of a complex mixture of microbes, cell debris and extracellular matrix
- Found on natural, wet surfaces
- Matrix is made of an extracellular slime layer
61
How plaque leads to tooth decay
- Sucrose in the diet is degraded by bacteria to produce acids
- Build up of plaque >> higher numbers of bacteria >> greater production of acids >> more demineralisation in teeth
62
Virulence factor
- Traits that give a microbe the ability to cause disease
- Endotoxins and exotoxins
- Production and release of enzymes
- Production of hameolysins
- Production of adherence factors (fimbriae, pili, glycocalyx)
63
Difference between endotoxin and extotoxin
- Endotoxins come from gram negative bacteria
- Exotoxins come from gram positive bcteria
- Endotoxins are within the cell wall
- Exotoxins are inside the cell
- Endotoxins are released when the cell dies and the cell wall breaks up
- Exotoxins are released and secreted by the living cell
64
Three types of haemolysis
- Alpha: partial lysis around colonies (green/grey colour)
- Beta: complete lysis
- Gamma: no haemolysis
65
Functions of parts of a light microscope
- Condenser: focuses light through the specimen
- Diaphragm: controls the amount of light going through the condenser
- total magnification = objective size x occular size
66
How would you increase contrast when looking at an unstained preparation with bright field
illumination?
- For unstained specimens, contrast can be increased by closing the condenser diaphragm
67
Selective and differential media
- Selective media only allow certain bacteria to grow while inhibiting others
- Differential media contain substances that will allow different bacteria to be distinguished
from each other
68
Four principle shapes of bacteria
- Bacillus (rods)
- Coccus (round)
- Spirals
- Vibrio (comma shaped)
69
Four principle types of microscopic arrangement
- Diplococcus (pairs)
- Chains
- Clusters
- Single cells
70
Apart from colony morphology and the Gram stain, what other methods could be used to identify an
unknown organism?
- Serotyping & detection of virulence factors (e.g. demonstration of specific enzymes)
- Using molecular techniques
- Observing biochemical characteristics
71
What is the difference between the incubation period of a disease and the invasive phase?
Incubation:
- No symptoms
- The initial invading microbes invade body
- They must overcome the host's defences (e.g. skin, immune system)
Invasive:
- Identifiable disease with dramatic increase in microbes (may continue to
death)
72
Microaerophile
- A microorganism that requires oxygen to survive, but these levels must be lower than what is present in the atmosphere
73
Mutualism
- Symbiotic relationship where both members benefit
74
Commensalism
- Symbiotic relationship where one member
| benefits without affecting the other
75
Parasitism
- Relationship where
one member benefits while the other is harmed
- also called amensalism or antagonism
