Module 4 - Notes Flashcards
What are the distinguishing features between proteobacteria and non-proteobacteria gram-negatives?
Proteobacteria are related to purple bacteria and non-proteobacteria gram-negatives are a group that is not related phylogenetically
What are the distinguishing features between amoebozoa, chromalveolata and excavate?
Amoeboza - Amoeboid movement vis pseudopodia produced by actin filament.
Chromalveolata - Similar origins of their plastids
Excavate - Depression on the surface of the cell (excavate)
How would you observe bacterial chemotaxis if you did not have access to agar plates and capillary tubes?
Darkfield microscopy
What is catabolism?
obtain energy from the breakdown of complex molecules
large molecules are broken down into smaller ones, releasing energy
What is anabolism?
synthesize cellular material from smaller parts
small molecules are assembled into larger ones, using energy
What do we mean by metabolism?
It is the sum of catabolism and metabolism
The overall behavior of the bacteria
What is an exergonic reaction?
A spontaneous reaction that releases energy
You are studying the metabolism of a new bacterium. If you are looking at how bacterium synthesizes complex molecules you are studying?
A. Catabolism
B. Anabolism
C. Biosynthesis
D. Anabolism & biosynthesis
D. Anabolism & biosynthesis
What is an endergonic reaction?
A reaction that requires energy to take place
What is a phototroph in microorganisms?
a microbe that gets energy from light
What is a chemotroph in microorganisms?
a microbe that gets energy from chemicals
What is an organotroph in microorganisms?
a microbe that gets electron donors from organic chemicals
reducing power
What is a lithotroph in microorganisms?
a microbe that gets electron donors from inorganic chemicals
reducing power
What is a heterotroph in microorganisms?
a microbe that obtains carbon from an external organic compound
What is an autotroph in microorganisms?
a microbe that obtains carbon from CO2
What is a photoautotroph?
energy source: light
Electron donor: N/A
Carbon source: CO2
What is a photoheterotroph?
energy source: light
Electron donor: N/A
Carbon source: Organic chemical
What is a photolithoautotroph?
energy source: light
Electron donor: Inorganic
Carbon source: CO2
What is a photoorganoheterotroph?
energy source: light
Electron donor: Organic
Carbon source: Organic chemical
What is a chemolithoautotroph?
energy source: Chemical
Electron donor: Inorganic
Carbon source: CO2
What is a chemolithoheterotroph?
energy source: Chemical
Electron donor: Inorganic
Carbon source: Organic chemical
What is a chemoorganoautotroph?
energy source: Chemical
Electron donor: Organic
Carbon source: CO2
What is a chemoorganoheterotroph?
energy source: Chemical
Electron donor: Organic
Carbon source: Organic chemical
You want to isolate a photautotroph from a mixed culture that also contains chemoorganoheterotrophs. What growth conditions would you select for the photoautotroph?
In the presence of light and the absence of a carbon source in the growth medium
(CO2 is present in the atmosphere)
How do microbes store energy?
Use NAD+ / NADH
They can store energy in complex molecules as well.
What do microbes need enzymes for?
to reduce the need for energy
enzymes lower the activation energy of reactions.
Why do we use antibiotic/antimicrobial treatments that target enzymes?
enzymes have binding sites
We can use inhibitors to prevent metabolism or to slow it down
What is the advantage of the breakdown of carbohydrates?
Breaking down carbohydrates requires energy but generates electrons and energy
What macromolecules can microbes break down?
Lipids
Polysaccharides
Proteins
Which organic compound(s) can provide energy to bacteria?
A. Glucose
B. Cellulose
C. DNA
D. Milk Casein
E. Milk Fat
F. All of the above
F. All of the above
They can all be used but it depends on whether or not the microbe has the pathways or enzymes to break them down.
Which type of respiration happens in the presence of oxygen?
aerobic
Which type of respiration happens in the absence of oxygen?
anaerobic
If the terminal electron acceptor is oxygen during respiration it is called ___________?
aerobic
If the terminal electron acceptor is something other than oxygen during respiration it is generally called _________?
anaerobic
The electron acceptor during respiration will drive the level of energy (ATP) produced. The terminal electron acceptor that produces the highest level of ATP is?
Oxygen
It will produce a maximum of 38 molecules of ATP
What is the rate-limiting step in respiration?
The terminal electron acceptor
If you grow bacteria in the presence of ammonium and sulfate, what type of metabolic class and metabolism will you select for?
A. Chemilithotrophy and anaerobic respiration
B. Chemilithotrophy and aerobic respiration
C. Chemoorganotrophy and anaerobic respiration
D. Chemoorganotrophy and aerobic respiration
A. Chemolithotrophy and anaerobic respiration.
Because of the lack of oxygen and organic compounds.
What is fermentation?
A metabolic pathway that requires an organic compound (electron donor) in the absence of oxygen
Which class of bacteria use fermentation?
chemoorganotrophs only
What are the products of fermentation?
Organic Acid
Alcohol or CO2
What is the end goal of fermentation?
Regeneration of NAD+
What is homofermentation?
when fermentation only produces 1 product
Example - an alcohol
What is heterofermentation?
When fermentation produces 2 different products
Example - an alcohol and an acid
Which of the following is NOT a condition for fermentation to occur?
A. Insufficient amount of appropriate final electron acceptor
B. Absence of genes encoding complexes and electron carriers in the electron transport system
C. Incomplete Krebs/TCA Cycle
D. Presence of an inorganic electron donor
D. Presence of an inorganic electron donor
The electron donor has to be organic for fermentation to occur
Which metabolic pathway yields the least amount of ATP?
Fermentation
What should you include in the medium for the bacterium that relies solely on fermentation to achieve the same energy production as the bacterium that uses aerobic respiration?
A. A larger quantity of electron acceptor
B. A larger quantity of organic electron donor
C. More oxygen
D. A larger quantity of inorganic electron donor
B. A larger quantity of organic electron donor
in fermentation, the rate-limiting step is the electron donor
What is unique about chemolithotrophy?
These microbes eat rocks
They use inorganic chemicals to generate their energy
They can be aerobic or anaerobic
What is unique about phototrophy?
Light energy drives electron flow and proton motor force
ATP Synthase generates ATP by photophosphorylation
Waste product is either:
oxygenic: O2 if cyanobacteria/algae/plant
-or-
anoxygenic
requires a photopigment
What are the characteristics of Anabolism? (biosynthesis)
Autotrophic - generates its own carbon
uses multiple pathways to fix CO2
If you omit a source of nitrogen and a source of carbon in your growth medium, what type of bacteria will grow under these conditions?
A. Heterotrophs with a Calvin cycle
B. Autotrophs with reverse citric acid cycle
C. Autotrophs that fix nitrogen
D. Heterotrophs that fix nitrogen
C. Autotrophs that fix nitrogen
heterotrophs require an external source of carbon so it has to be an autotroph
What is Nitrogen fixation in bacteria and archaea?
bacteria and archaea that can convert inorganic nitrogen (from the atmosphere) to useable nitrogen (N2)
What would you measure to differentiate and classify phototrophs?
Waste products:
- Oxygenic: O2
- Anoxygenic
What is the most common type of cell division in bacteria?
A. Budding
B. Binary fusion
C. Mitosis
D. Fragmentation
B. Binary fusion
What is the most common way bacteria divide?
Binary fission
1 cell becomes 2 cells
Which of the following bacteria groups divide by budding?
A. Planctomycetes
B. Proteobacteria
C. Firmiculates
D. Spirochetes
A. Planctomycetes
What is the cell cycle of bacteria?
bacterial cell cycle
1 Chromosome replication
2 Elongation
3 Segregation
4 Z-ring formation (septum)
5 Division
Which bacteria does not have a z-ring?
They have peptidoglycan but no cell wall
Chlamydia
You observe ghost cells in your bacterial culture. What is the best explanation?
A. Bacteria are ejecting their DNA due to sporulation
B. These bacterial cells are dead
C. The Z-ring is formed prior to segregation during the cell division cycle
D. All of the above
C. The Z-ring is formed prior to segregation during the cell division cycle
if the chromosome isn’t pulled towards each end, you’ll have 2 chromosomes in one end and then when the ring closes you have an empty cell
How would you describe planktonic bacteria?
free-living
(divide, grow, swim around)
How would you describe a biofilm?
assembled community of bacteria attached to a surface
What are the 4 key steps to forming a biofilm?
1 Attachment (reversible -> irreversible)
2 Growth
3 Maturation
4 Detachment
What is significant about a matrix in biofilm formation?
the matrix helps protect against the environment
Once bacteria forms a matrix, it is not a target of antibiotics.
not all of the cells in the matrix are metabolically active. Some are inactive but still alive
You work in the food industry and biofilms are a major problem. You must keep surfaces free of bacterial contamination at all times. What step of biofilm formation should you target?
A. Attachment
B. Colonization
C. Maturation
D. Dispersion
A. Attachment
Which of the following would result in a doubling of the population?
A. Sporulation
B. Cell death
C. Budding division
D. Formation of myxospores
E. Germination
F. Formation of Chlamydia elementary bodies
C. Budding cell division
What are the methods used to count bacteria?
Direct count using:
microscopy
current - coulter counter
Indirect count using:
Most probable number
turbidimetric (optical density)
What are the methods used to count viable (live) bacteria
Dilution
Plating
What are the pros/cons of direct count using microscopy and how does it work?
You count the #of bacteria in the squares and calculate the volume
Works better with larger cells
Difficult with mobile bacteria
You get a total count of bacterial cells, dead or alive
What are the pros/cons of direct count using current and how does it work?
Measure the current passing through a bacterial sample in an electrolytic solution.
You get a total count, dead or alive
It is an approximate number based on the reading on the counter
What are the pros/cons of indirect count using dilution and how does it work?
Dilute a fixed volume of bacteria repeatedly until you get to point where you can count them. (between 30-300 cells)
Takes time between each dilution to grow the colony
Makes sure that what you are counting are metabolically active or living
1 colony = one cell
What are the pros/cons of indirect count using plating and how does it work?
Pour plate
Diluted bacterial sample is mixed with agar
Sample is poured onto a plate, swirled and then allowed to solidify
plate is incubated until colonies grow
What are the pros/cons of indirect count using plating and how does it work?
Spread plate
Diluted bacterial sample is poured onto a solid medium and spread evenly over the surface
Plate is incubated until the colonies grow
What are the pros/cons of indirect count using Most Probable Number and how does it work?
A statistical method that estimates the number of viable cells in a sample
Usually used for water quality (counting coliforms)
Bacterial growth is assessed through a change in the colour of the broth from red to yellow as lactose is fermented.
What are the pros/cons of indirect count using Optical Density (Turbidmetric) and how does it work?
As bacteria grows it prevents light passing through (Deflect/refract) so you look at the amount of light being blocked.
Cannot determine if the cells are dead or alive
Which of the following methods would be used to measure the concentration of bacterial contamination in processed peanut butter?
A. Total plate count
B. Direct counting of bacteria on a calibrated slide under the microscope
C. turbidity measurement
D. dry weight measurement
A. Total plate count
best option because the peanut butter won’t interfere with your measurements.
What are the 4 phases of bacterial growth?
- Lag Phase (no increase in number of living bacterial cells)
- Log Phase (exponential increase in number of living cells)
- Stationary Phase (plateau in number of living bacterial cells - rate of death = rate of division)
- Death or Decline Phase (exponential decrease in number of living cells)
During which phase would antibiotics be most effective?
A. Lag phase
B. Log phase
C. Stationary phase
D. Death phase
Log phase
antibiotics work against metabolically and dividing bacteria
What is the generation time of bacteria?
the time for the population to double
What would be the consequence of blocking DNA replication, elongation, segregation, Z-ring formation. and division of the cell?
DNA Replication - will block cell division, the cell will remain the same
Elongation - will block growth of the cell, cell size will remain the same but have 2 chromosomes
Segregation - Will block movement of the chromosomes towards the pole, the cell size will be 2X normal size with 2 chromosomes in the middle
Z-ring Formation - Will block septum formation, cell size will be 2X normal with chromosome copy at each pole
Division - Will block detachment of 2 cells - 2 normal cells attached at the septum
What does auxotroph mean?
the cell requires the addition of specific macromolecules because it does not synthesize them.
They need a nutrient
What does prototroph mean?
The cell is self-sufficient
They generate their own macromolecules from basic elements
What are the essential nutrients to grow microbes in the lab?
carbon source
nitrogen source
phosphorus source
sulfur source
electron donors
electron acceptors
enzyme cofactors
anabolism
catabolism
What are Eutrophs/Copiotrophs?
those that grow in high levels of nutrients.
What are Oligotrophs?
those that require low nutrient levels to grow.
High nutrient levels prevent growth
What needs to be added to your growth medium to meet the requirement of a chemoorganoheterotroph?
A. a source of organic carbon
B. A source of organic electron donor
C. A source of fixed inorganic nitrogen
D. All of the above
E. None of the above
C. A source of fixed inorganic nitrogen
Hetero = organic carbon
chemoorgano = organic electron donor
Nitrogen is required
What is a defined growth medium?
A medium where you know exactly what it contains.
What is a complex growth medium?
a medium where the composition is unknown
What is a minimal growth medium?
A medium that meets the minimum requirements
Only in defined mediums can be minimal
What is a selective medium?
A medium that restricts the growth of undesirables
It favors the growth of desirables
What is a differential medium?
A medium that can distinguish between different types of bacteria
ex. pH indicator
Which medium would you use to select against a tryptophan auxotroph?
A. A complex medium
B. A defined medium without tryptophan
C. A selective medium with tryptophan
D. A differential medium with tryptophan
B. A defined medium without tryptophan
Auxotroph mean it needs tryptophan
