Exam 2 Flashcards
To get to 100%
Anthropomorphism
Ascribing human form or attributes to non-human creature or objects
Teleology
The belief that purpose and design are a part of, or are apparent in, nature
What is one problem of Teleology?
The idea of “want”, “intent”, “motivation”.
What happened when Spontaneous Generation was first discovered?
The belief that after broth was boiled, it look a lot time for organisms to grow back. However, it was discovered that it was just dust particles falling in.
What was the swan neck?
It prevented dust from falling in due to shape of flask.
What was the conclusion of Spontaneous Growth?
It takes a cell to make a cell
What does “growth” refer to in Microbiology?
It always refers to population growth, an increase in cell numbers.
What happens as a single cell starts to grow?
They increase in biomass to the point where they break into two daughter cells
What is the name of the original cell?
“Mother” Cell
What is the name of the two cells that come out of the “Mother” Cell?
“Daughter” Cells
Where do cells divide in Binary Fission?
Right down the middle
Where must new material be made in Binary Fission?
It must be made in the center of the cell
What two problems must Binary Fission solve?
Division Machinery and Finding The Middle
What is Cytokinesis?
When FtsZ is now present in the bacterial cell.
What is the name of the cell division protein?
FtsZ
What kind of structure does FtsZ form?
Forms ring-like scaffold at midcell.
What does Cytokinesis recruit?
Recruits cell wall synthesis machinery
What is the function of polymerization?
That different conformations may promote contractions of the ring.
First step in FtsZ Function: Recruit Divison Machinery?
FtsZ polymerizes at a new division site
Second step in FtsZ Function: Recruit Divison Machinery?
FtsZ recruits other “Fts” cell division proteins
Third step in FtsZ Function: Recruit Divison Machinery?
Peptidoglycan synthesis machinery loads onto complex. Brings everything into the membrane so that everything can work together.
Why are bacterial cell divison proteins called Fts?
“Filamentation Temperature Sensitive”
What would happened at high temperatures to cell division to a mutant?
They would filament. This would suggest that they had a cell divison problem where they could grow indefinitely but they had issues with dividing.
What does the “Min” System contain?
MinC and MinD
What is MinC
Inhibits FtsZ polymerization
What is MinD
Membrane bought anchor and activator for MinC
Where are MinC and MinD localized?
To the poles.
How are MinC and MinD kept out of the middle of the cell?
MinE - Topological Determinant. Forms at the end of MinC shells and inhibits MinC.
What is Noc?
Nucleoid Occulsion system, prevents chromosomes from being guillotined. Coats chromosome and inhibits FtsZ from polymerizing over chromosome
What happens in absence of MinC/D
Nod prevents FtsZ from forming over nucleoid, but division plane random. Results in minicells and that is lethal.
What are Autolysins?
Like LytF, they are peptidoglycan remodeling enzymes. Break peptidoglycan to separate daughter cells.
OOTW - Caulobacter Crescentus
Environmental bacterium that grows in dilute water, and very low nutrients. Has a stalk (tail off the end of the cell). Stalk grows during nutrients starvation to elongate surface area.
Each division produces two different cell types; swimmer cell (cell cycle arrested) and stalked cell (actively dividing).
1. In order for it to grow, has to grow onto a stalk cell and lose the flagellum. It sticks to the surface and begins divison.
What are the four ways to measure growth?
Direct Counting
Viable Counting
Spectrophotometry
Flow Cytometry
Advantages of Direct Counting?
Do not need to grow samples, works for any sample
Disadvantages of Direct Counting?
Cells must be evenly distributed
Cannot distinguish which cells are dead or alive
Viable Counting Assumption?
That each living cell is a colony formung unit, and will grow to become a colony.
Counting rule for Viable Counting?
30-300.
Advantages of Viable Counting?
Allows you to measure the number of viable cells. Has colony forming units.
Disadvantages of Viable Counting?
Only works with cultureable bacteria. Assumes eachcolony originates from a single cell and problems with clumping
How does Spectrophotometry work?
You shine light through the culture. The more dense the culture is, the more light that will be absorbed.
Tudbidity definition
How dense the culture is to the eye.
Why is OD600 used as the wavelength?
Used because you can take that number and then use viable or direct counting
Advantages of Spectrophotometry?
Most rapid technique, reliable
Disadvantages of Spectrophotometry?
Organisms must be cultureable. PRoblems with cell clumps are severe and indirect. Changes in size can affect reading
What is Flow Cytometry?
Bacteria flows through tube and are individually counted.
Advantages of Flow Cytometry?
Extremely accurate. Can measure size.
Disadvantages of Flow Cytometry?
Slow, problems with clumping and dead cells.
What is Exponential Growth?
When the time between generations is the same. Cells double at the same rate.
Generation time?
Time required for a cell population to double in size, respresented as (g).
What are the two types of Growth Environments?
Batch Culture and Continuous Culture
What is Batch Culture?
- Closed system where no nutrients enter and no waste products leave.
- Eventually starvation with occur where nutrient limitation will set in.
- Good model for : contaminated food, some infections
- Poor model for : the environment, some infections, continual flux of materials and waste products.
What is Continuous Culture?
- Open system with fresh nutrients flow in and waste products flow out
- Fresh nutrients flow through system, allowing for continuous growth. Stay in exponential phase for forever.
- As the dilution rate increases, more nutrients flow in at a faster rate and bacteria grow faster to keep up with the faster flow.
- Each bacteria has a maximum growth rate however. The bacteria cannot keep up and will get washed out.
