Lab 7: Bacterial Growth

Question 1

Define a batch culture

Answer 1

The making of a culture in which bacteria are initially provided with a finite amount of nutrients and space, and nothing is ever added to the culture. A closed system.

Question 2

Define a continuous culture

Answer 2

-An open-system culture that utilizes a chemostat and probe to monitor and adjust pH, oxygen, and temperature.
-It has 3 openings; one to allow atmosphere to enter, one to allow for ‘refreshing’ , and one to allow for collection.

Question 3

What did we do during the bacterial growth lab? (lab 7)

Answer 3

We measured the optical density of our samples at 3 different times using a spectrophotometer, and made and plated serial dilutions from that sample at 3 different times

Question 4

List and describe the 4 phases that happen in a batch culture (closed system)

Answer 4

1) Lag: No growth, but genes are being turned on/off based on available nutrients.
2) Log: Rapid growth, use of nutrients, and waste generation
3) Stationary: Cell division happens at the same rate as cell death, can last days
4) Death: Nutrients are depleted, toxic wastes accumulate, cell division is less than cell death

Question 5

What is the X axis of the graph of closed-culture growth? What is the Y axis?

Answer 5

1) X-axis: Time
2) Y-axis: Number of bacteria

Question 6

What were the serial dilutions we made during the bacterial growth lab? (lab 7)

Answer 6

1) .1ml into 9.9ml
2) 1ml into 9ml
3) 1ml into 9ml

Question 7

What does a spectrophotometer measure?

Answer 7

The amount of light that passes through the medium

Question 8

What type of flask makes using a spectrophotometer easier? What makes it easier?

Answer 8

A Nephlo flask, which has a cuvette built into its side

Question 9

What is 0.01 equal to in scientific notation? What about as a fraction?

Answer 9

10^-2; 1/100

Question 10

What is 0.1 equal to in scientific notation? What about as a fraction?

Answer 10

10^-1; 1/10