Growth

Question 1

What is minimal media?

Answer 1

• media that only contains the absolutely necessary components required for growth

Question 2

What is defined medium?

Answer 2

• every component and its quantity are known

Question 3

What is undefined medium?

Answer 3

• some components/quantities are not known exactly

Question 4

What is a rich medium?

Answer 4

• contains components allowing for a high growth rate that is not strictly necessary for basic growth
• tends to be rich in nutrients, complex mixtures: unknown mixture of ingredients

Question 5

What is turbidity and what does it measure?

Answer 5

• it is cloudiness; the amount of light passing through a culture
• more bacteria = more light scattered
• not the most accurate, can’t tell alive from the dead

Question 6

What is the viable cell count method for measuring growth?

Answer 6

• dilute sample culture, spread dilutions onto solid plate medium
• only living cells will grow on plates
• accurate for number of alive cell count

Question 7

What the direct cell count method for measuring growth?

Answer 7

• load sample of culture into counting chamber and view in the microscope
• count cells directly
• can’t really determine living vs dead

Question 8

What kind of growth pattern is often graphed when measuring bacterial growth?

Answer 8

• because cells reproduce through binary fission, you get exponential growth
• seen better through a log scale gragh

Question 9

What is the lag phase in the overall growth phase of bacteria?

Answer 9

• when cells are adapting to new environment

- not really any activity

Question 10

What is the exponential phase of the overall growth phase of bacteria?

Answer 10

• cells grow and divide exponentially at consistent rate

- see exp. growth

Question 11

What is the exponential phase of the overall growth phase of bacteria?

Answer 11

• cells grow and divide exponentially at a consistent rate

- see exp. growth

Question 12

What is the stationary phase of the growth phase in bacteria?

Answer 12

• cells are no longer actively growing
• nutrients are used, waste builds up
• cells undergo change to survive

Question 13

What is the death/long-term stationary phase of the cell growth phase?

Answer 13

• cell population lowers exponentially

- different cell variants become dominant in succession

Question 13

What is the death/long-term stationary phase of the cell growth phase?

Answer 13

• cell population lowers exponentailly

- different cell variant become damominnat in succession

Question 14

What is balanced cell growth?

Answer 14

• in exp. phase, cell components increase by the same proportion
• mean cell size is constant in balanced growth
• balanced cell growth requires an unchanging environment, low cell density

Question 15

What is a chemostat?

Answer 15

• a device to allow continuous balanced growth through constant dilution

Question 16

What are the equations needed for exp. growth?

Answer 16

• look them up idiot

Question 17

How does temperature affect cell growth rate?

Answer 17

• each species has its own optimum growth temperature

- more leeway under the optimal temp than above it, so worse growth once optimal temp has been passed

Question 18

What happens to cells at the extremes of temperature?

Answer 18

• highest temperatures: proteins denature

- lowest temperatures: weakened hydrophobic interactions, alter protein

Question 19

How do microbes adjust to lower temperatures?

Answer 19

• easier to adjust to lower temperatures

- proteins and fatty acid composition made a little more unstable to complete said reactions

Question 20

How do microbes adjust to higher temperatures?

Answer 20

• proteins constructed to withstand denaturing
• chaperone proteins/ Heat shock proteins to hep fold and keep folded properly
• DNA- binding proteins to hold it together
• Reverse Gyrase: promotes supercoiling- tightens DNA double helix

Question 21

How can some microbes grow in saturating concentrations of salt?

Answer 21

• two stresses
  1) dries out cell
  2) lowers cell turgor pressure
• Most cells respond by increasing their internal concentration of solutes

Question 22

How does the process of binary division start in gram-negative and gram-positive cells?

Answer 22

• gram-negative: bacteria generally male a constriction at mid-cell
• gram-positive: may or may not constrict., can just square off usually

Question 23

What is the process of regulating chromosome segregation when binary fission occurs?

Answer 23

• draw it out

- ParA grabs ParB which has ParS, and essentially pulls the chromosomes to opposite poles of the cell

Question 24

What is the role of FtsZ in septation of the cell?

Answer 24

• fts: temperature-sensitive, cannot divide normally at 42
• similar to eukaryotic cytoskeletal protein tubulin and actin
• FtsZ forms a ring, recruits other cell division proteins, and determines location of the septation

Question 25

What is the role of min, minCD, and minE in fission?

Answer 25

Min: proteins normally prevent FtsZ from polymerizing at the wrong site
MinCD: polymerizes out from poles alternating, and depolymerizes FtsZ
MinE: prevents MinCD from polymerizing in the middle of the cell, “chews it back to the poles

Question 26

What is the role of the divisome?

Answer 26

• works to connect FtsZ constriction to cell wall synthesis

Question 27

What is a halophile?

Answer 27

• a halophile is a microbe that likes a high concentration of salt

Question 28

What is an acidophile?

Answer 28

an acidophile is an organism that thrives in acidic conditions

Question 29

What is an alkalophilic microbe?

Answer 29

an organism that thrives in alkaline conditions

Question 30

What is barophilic organism?

Answer 30

organism that thrives under high environmental conditions