BIOL 3150 - MICROBIOLOGY EXAM QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS VERIFIED
What is Microbiology?
The study of microorganisms
Robert Hooke
Microscope 1655
Antoni van Leeuwenhoek
Discovered bacteria with the microscope --> 1676
Condenser lens:
Focuses light on specimen
Objective Lens:
Magnifies specimen
Ocular lens
Further magnifies image (10X)
How do you determine the total magnification?
Multiply objective by ocular to find total magnification
Microscopy Field of view
As magnification increases the FOV decreases
What happens to the depth of field as the magnification increases?
As mag increases depth of field decreases
Light microscopes:
,Used to look at intact cells under relatively low magnification
Resolution
The ability to distinguish two adjacent objects as separate and distinct
- determined by the wavelength of light used and the numerical aperture.
- R = 0.61lambda/NA
Resolving Power:
How close can two things be, and still be seen as two separate entities
- Typical = 0.2 micrometres
Oil Immersion lens
The oil has a high refractive index
Makes images sharper
Types of light microscopy (4)
Bright field
Phase contrast
Dark field
Fluorescence
Improving Contrast in Light Microscopy
Staining is an easy way to improve contrast
Simple versus Differential Stains
,Simple Stain: One dye used to visualise a microorganism on a slide
Differential Stain: Two dyes used to distinguish microorganisms
Louis Pasteur
A French chemist, this man discovered that heat could kill bacteria that otherwise
spoiled liquids including milk, wine, and beer.
- Dust could not get in due to swan neck
- Medium did not contaminate until mixture
Robert Koch
Father of modern bacteriology
The 4 Postulates
1.) Pathogenicity - Suspected pathogen must be present in all cases of the disease and
absent from healthy animals
a.) Isolate a blood sample from organism
2.) Suspected pathogen must be grown in pure culture
b.) Pure culture is needed to have more of the sample of interest and specificity to a
specific pathogen
3.) Cells from a pure culture of the suspected pathogen must cause disease in a healthy
animal
, c.) Take a healthy new mouse and inoculate it (expose to bacteria)
4.) The suspected pathogen must be reisolated and shown to be the same as the
original
d.) The new diseased animal must be used to take a sample to determine if it is the
same causative agent (pathogen)
Risk Group Classification
1.) Pathogenicity: How likely is it that this organism will cause the disease
2.) What is the mode of transmission/host range: How is it spread? (sneezing, blood
contact, human-human) and to who or what?
3.) Availability of effective preventative measures
4.)Availability of effective treatment
Properties of all cells (4)
1.) Structure
2.) Metabolism
3.) Growth
4.) Evolution
Properties of some cells (4)
1.) Differentiation
2.) Communication
WITH COMPLETE SOLUTIONS VERIFIED
What is Microbiology?
The study of microorganisms
Robert Hooke
Microscope 1655
Antoni van Leeuwenhoek
Discovered bacteria with the microscope --> 1676
Condenser lens:
Focuses light on specimen
Objective Lens:
Magnifies specimen
Ocular lens
Further magnifies image (10X)
How do you determine the total magnification?
Multiply objective by ocular to find total magnification
Microscopy Field of view
As magnification increases the FOV decreases
What happens to the depth of field as the magnification increases?
As mag increases depth of field decreases
Light microscopes:
,Used to look at intact cells under relatively low magnification
Resolution
The ability to distinguish two adjacent objects as separate and distinct
- determined by the wavelength of light used and the numerical aperture.
- R = 0.61lambda/NA
Resolving Power:
How close can two things be, and still be seen as two separate entities
- Typical = 0.2 micrometres
Oil Immersion lens
The oil has a high refractive index
Makes images sharper
Types of light microscopy (4)
Bright field
Phase contrast
Dark field
Fluorescence
Improving Contrast in Light Microscopy
Staining is an easy way to improve contrast
Simple versus Differential Stains
,Simple Stain: One dye used to visualise a microorganism on a slide
Differential Stain: Two dyes used to distinguish microorganisms
Louis Pasteur
A French chemist, this man discovered that heat could kill bacteria that otherwise
spoiled liquids including milk, wine, and beer.
- Dust could not get in due to swan neck
- Medium did not contaminate until mixture
Robert Koch
Father of modern bacteriology
The 4 Postulates
1.) Pathogenicity - Suspected pathogen must be present in all cases of the disease and
absent from healthy animals
a.) Isolate a blood sample from organism
2.) Suspected pathogen must be grown in pure culture
b.) Pure culture is needed to have more of the sample of interest and specificity to a
specific pathogen
3.) Cells from a pure culture of the suspected pathogen must cause disease in a healthy
animal
, c.) Take a healthy new mouse and inoculate it (expose to bacteria)
4.) The suspected pathogen must be reisolated and shown to be the same as the
original
d.) The new diseased animal must be used to take a sample to determine if it is the
same causative agent (pathogen)
Risk Group Classification
1.) Pathogenicity: How likely is it that this organism will cause the disease
2.) What is the mode of transmission/host range: How is it spread? (sneezing, blood
contact, human-human) and to who or what?
3.) Availability of effective preventative measures
4.)Availability of effective treatment
Properties of all cells (4)
1.) Structure
2.) Metabolism
3.) Growth
4.) Evolution
Properties of some cells (4)
1.) Differentiation
2.) Communication
