Microbiology- Mid Term Study Guide
Essay Questions
1. Gram Positive vs. Gram Negative & Procedure (2 Part Question, list 5 things, they should match,
should start with smear preparation)
First: Smear Preparation Steps
1. Organism growing in liquid = small drop of broth on surface of slide
2. Organism growing on solid surface = mixed into small drop of water
3. Spread organism on slide in circular motion
4. Let air dry, then pass through flame
Second: Gram Staining Procedure
1. Flood the smear with basic dye crystal violet for 1 minute and rinse with water. Crystal violet is the primary
stain
2. Flood the smear with an iodine solution for 1 min and then rinse with water. Iodine is a mordant, a substance
that binds to a dye and makes it less soluable. After this step all cells remain purple
3. Rinse the smear with a solution of ethanol and acetone for 10-30sec, then rinse with water. This solution is a
decolorizing agent, breaks down the thin cell wall of gram negative cells, allowing the stain and mordant to be
washed away. Gram negative cells are colorless. Gram positive remain purple
4. Flood the smear with safranin for 1 min, then rinse with water. Red counterstain provides a contrasting color
to primary stain.
**Most Critical Step is washing with alcohol b/c that tells the difference between gram positive
and gram negative**
2. 5 Scientist and their Contribution to Microbiology (2-3sentences each, bullets are fine too)
Antoni Leeuwenhoek Carolus Linnaeus Robert Koch Alexander Louis Pasteur
Fleming
-Consider him the father of - Developed a - Developed Heat - Pasteur con
Microbiology taxonomic system Fixation a series of
- Began making and using for naming plants - Germ Theory experiments
simple microscopes and animals and - Proved that addressed th
-Often made a new grouping similar microorganisms cause of
microscope for each new organism can cause fermentation
specimen together disease -Led to the
-Examined water and - A bacterium development
visualized tiny animals, causes anthrax pasteurizatio
fungi, algae, and single- - Postulates - Process of h
celled protozoa; - Direct link of a liquids just e
“”animalcules” specific microbe to kill most b
By the end of the to a specific - Began the fi
19th century, disease industrial
these organisms microbiology
were called - Intentional
microorganisms. microbes for
o Leeuwenhoek’s manufacturin
microorganisms can products
be grouped into six - Pasteurizati
categories: (Apply high h
Bacteria a short perio
Achaea times
Fungi Kills most
Protozoa organisms no
Algae
Small
, multicellular
animals
3. Stages of Bacterial Growth (2-3 Characteristics)
Lag phase is no increase in number of living bacterial cells.
Cells are adjusting to their new environment
Most cells do not reproduce immediately but instead actively synthesize enzymes to
utilize novel nutrients in the medium
The lag phase can last less than an hour or can last for days, depending on the species and
the chemical and physical conditions of the medium
Log Phase is an exponential increase in number of living bacterial cells.
Population increases logarithmically, and the reproductive rate reaches a constant as DNA
and protein syntheses are maximized.
Populations in log phase are more susceptible to antimicrobial drugs that interfere with
metabolism and to drugs that interfere with the formation of cell structures
Populations in log phase are preferred for Gram staining because most cells’ walls are
intact—an important characteristic for correct staining.
Stationary phase is a plateau in number of living cells; rate of cell division and death roughly
equal.
The metabolic rate of surviving cells declines
Cells in this phase are stress tolerant because they are adapted for challenging conditions,
such as heat, high salt concentrations, and the presence of antibiotics
Death or decline phase is an exponential decrease in number of living bacterial cells.
Some cells remain alive and continue metabolizing and reproducing, but the number of
dying cells exceeds the number of new cells produced so that eventually the population
decreases to a fraction of its previous abundance
4. Prokaryotes vs. Eukaryotes (5 characteristics each)
Prokaryotes Eukaryotes
Bacteria & Archea Algae, protozoa, fungi, animals and plants
No Nucleus multicellular parasites
Can Read DNA and make protein simultaneously Has nucleus
Lack various internal structures bound w/ DNA bound to protein
phospholipid membranes Has organelles
No organelles Larger in size
Smaller in size 80s Ribosomes
Circular DNA Mitosis and Meiosis
70s Ribosomes Complex structure
Binary Fission Chromosomes paired (diploid or more)
Single Chromosomes
5. Parts of Virus
6. 5 Stages of Viral Replication ( Lytic Stage)
1. Attachment
Contact w/ bacteria occurs by random collision
Molecular currents move Virons through environment
Tail fibers responsible for attachment
Phage attachment specific
2. Entry
Must get past cell wall/membrane
, Lysozyme released to weaken cell wall
Phage injects genome through tube into bacterium
3. Synthesis
Stops synthesizing own material, only viral aspects from genome
4. Assembly
Phages spontaneously attach to one another to form new capsid heads
Little or no enzyme help
For some viruses enzymes pump genome into assembled capsid under high pressure
5. Release
Virons are release from the cell as lysozyme completes its work on cell wall and
bacterium disintegrates
7. Intercellular vs Extracellular
Extracellular
-Called virion
-Protein coat (capsid) surrounding nucleic acid
-Nucleic acid and capsid, also called nucleocapsid
-Some have phospholipid envelope
-Outermost layer provides protection and recognition sites
for host cells
Intercellular
-Capsid removed
-Virus exists as nucleic acid
8. Viroid , Virion,Prion
Viroids Prions Virion
- Extremely small, circular pieces of - Proteinaceous infectious agents - consists of a protein coat,
RNA that are infectious and - Cellular PrP a capsid, surrounding a nu
pathogenic in plants - Made by all mammals acid core
- Similar to RNA viruses but lack - Normal, functional structure has α- - Together, a viral nucleic ac
capsid helices its capsid are also called a
- May appear linear because of - Prion PrP nucleocapsid, which in ma
hydrogen bonding - Disease-causing form has β-sheets cases can crystallize like
- Viroidlike agents affect some fungi - Prion PrP causes cellular PrP to crystalline chemicals
refold into prion PrP - Some virions have a
-Prion diseases phospholipid membrane c
- Spongiform encephalopathies an envelope surrounding
- Large vacuoles form in brain nucleocapsid.
- Characteristic spongy appearance - The outermost layer of a v
- BSE, vCJD, kuru (capsid or envelope) provi
- Transmitted by ingestion, the virus both protection a
transplantation, or contact of recognition sites that bind
mucous membranes with infected complementary chemicals
tissues surfaces of their specific h
- Prions are destroyed by cells.
incineration or autoclaving in
concentrated sodium hydroxide
9. Bacteria vs Archea
Bacteria Archea
-Unicellular and lack nuclei -Unicellular and lack nuclei
Essay Questions
1. Gram Positive vs. Gram Negative & Procedure (2 Part Question, list 5 things, they should match,
should start with smear preparation)
First: Smear Preparation Steps
1. Organism growing in liquid = small drop of broth on surface of slide
2. Organism growing on solid surface = mixed into small drop of water
3. Spread organism on slide in circular motion
4. Let air dry, then pass through flame
Second: Gram Staining Procedure
1. Flood the smear with basic dye crystal violet for 1 minute and rinse with water. Crystal violet is the primary
stain
2. Flood the smear with an iodine solution for 1 min and then rinse with water. Iodine is a mordant, a substance
that binds to a dye and makes it less soluable. After this step all cells remain purple
3. Rinse the smear with a solution of ethanol and acetone for 10-30sec, then rinse with water. This solution is a
decolorizing agent, breaks down the thin cell wall of gram negative cells, allowing the stain and mordant to be
washed away. Gram negative cells are colorless. Gram positive remain purple
4. Flood the smear with safranin for 1 min, then rinse with water. Red counterstain provides a contrasting color
to primary stain.
**Most Critical Step is washing with alcohol b/c that tells the difference between gram positive
and gram negative**
2. 5 Scientist and their Contribution to Microbiology (2-3sentences each, bullets are fine too)
Antoni Leeuwenhoek Carolus Linnaeus Robert Koch Alexander Louis Pasteur
Fleming
-Consider him the father of - Developed a - Developed Heat - Pasteur con
Microbiology taxonomic system Fixation a series of
- Began making and using for naming plants - Germ Theory experiments
simple microscopes and animals and - Proved that addressed th
-Often made a new grouping similar microorganisms cause of
microscope for each new organism can cause fermentation
specimen together disease -Led to the
-Examined water and - A bacterium development
visualized tiny animals, causes anthrax pasteurizatio
fungi, algae, and single- - Postulates - Process of h
celled protozoa; - Direct link of a liquids just e
“”animalcules” specific microbe to kill most b
By the end of the to a specific - Began the fi
19th century, disease industrial
these organisms microbiology
were called - Intentional
microorganisms. microbes for
o Leeuwenhoek’s manufacturin
microorganisms can products
be grouped into six - Pasteurizati
categories: (Apply high h
Bacteria a short perio
Achaea times
Fungi Kills most
Protozoa organisms no
Algae
Small
, multicellular
animals
3. Stages of Bacterial Growth (2-3 Characteristics)
Lag phase is no increase in number of living bacterial cells.
Cells are adjusting to their new environment
Most cells do not reproduce immediately but instead actively synthesize enzymes to
utilize novel nutrients in the medium
The lag phase can last less than an hour or can last for days, depending on the species and
the chemical and physical conditions of the medium
Log Phase is an exponential increase in number of living bacterial cells.
Population increases logarithmically, and the reproductive rate reaches a constant as DNA
and protein syntheses are maximized.
Populations in log phase are more susceptible to antimicrobial drugs that interfere with
metabolism and to drugs that interfere with the formation of cell structures
Populations in log phase are preferred for Gram staining because most cells’ walls are
intact—an important characteristic for correct staining.
Stationary phase is a plateau in number of living cells; rate of cell division and death roughly
equal.
The metabolic rate of surviving cells declines
Cells in this phase are stress tolerant because they are adapted for challenging conditions,
such as heat, high salt concentrations, and the presence of antibiotics
Death or decline phase is an exponential decrease in number of living bacterial cells.
Some cells remain alive and continue metabolizing and reproducing, but the number of
dying cells exceeds the number of new cells produced so that eventually the population
decreases to a fraction of its previous abundance
4. Prokaryotes vs. Eukaryotes (5 characteristics each)
Prokaryotes Eukaryotes
Bacteria & Archea Algae, protozoa, fungi, animals and plants
No Nucleus multicellular parasites
Can Read DNA and make protein simultaneously Has nucleus
Lack various internal structures bound w/ DNA bound to protein
phospholipid membranes Has organelles
No organelles Larger in size
Smaller in size 80s Ribosomes
Circular DNA Mitosis and Meiosis
70s Ribosomes Complex structure
Binary Fission Chromosomes paired (diploid or more)
Single Chromosomes
5. Parts of Virus
6. 5 Stages of Viral Replication ( Lytic Stage)
1. Attachment
Contact w/ bacteria occurs by random collision
Molecular currents move Virons through environment
Tail fibers responsible for attachment
Phage attachment specific
2. Entry
Must get past cell wall/membrane
, Lysozyme released to weaken cell wall
Phage injects genome through tube into bacterium
3. Synthesis
Stops synthesizing own material, only viral aspects from genome
4. Assembly
Phages spontaneously attach to one another to form new capsid heads
Little or no enzyme help
For some viruses enzymes pump genome into assembled capsid under high pressure
5. Release
Virons are release from the cell as lysozyme completes its work on cell wall and
bacterium disintegrates
7. Intercellular vs Extracellular
Extracellular
-Called virion
-Protein coat (capsid) surrounding nucleic acid
-Nucleic acid and capsid, also called nucleocapsid
-Some have phospholipid envelope
-Outermost layer provides protection and recognition sites
for host cells
Intercellular
-Capsid removed
-Virus exists as nucleic acid
8. Viroid , Virion,Prion
Viroids Prions Virion
- Extremely small, circular pieces of - Proteinaceous infectious agents - consists of a protein coat,
RNA that are infectious and - Cellular PrP a capsid, surrounding a nu
pathogenic in plants - Made by all mammals acid core
- Similar to RNA viruses but lack - Normal, functional structure has α- - Together, a viral nucleic ac
capsid helices its capsid are also called a
- May appear linear because of - Prion PrP nucleocapsid, which in ma
hydrogen bonding - Disease-causing form has β-sheets cases can crystallize like
- Viroidlike agents affect some fungi - Prion PrP causes cellular PrP to crystalline chemicals
refold into prion PrP - Some virions have a
-Prion diseases phospholipid membrane c
- Spongiform encephalopathies an envelope surrounding
- Large vacuoles form in brain nucleocapsid.
- Characteristic spongy appearance - The outermost layer of a v
- BSE, vCJD, kuru (capsid or envelope) provi
- Transmitted by ingestion, the virus both protection a
transplantation, or contact of recognition sites that bind
mucous membranes with infected complementary chemicals
tissues surfaces of their specific h
- Prions are destroyed by cells.
incineration or autoclaving in
concentrated sodium hydroxide
9. Bacteria vs Archea
Bacteria Archea
-Unicellular and lack nuclei -Unicellular and lack nuclei
