Lecture 9

Question 1

Lag Phase

Answer 1

Adaption to new growth conditions. Base of the line. Straight. Not many cells

Question 2

Exponential Phase

Answer 2

Exponential Growth from binary fission

Question 3

Stationary Phase

Answer 3

Starvation begins to happen and organisms eat the dead ones. Straight line

Question 4

Death Phase

Answer 4

More cells die than divide. Negative slope

Question 5

Growth Rate Constant

Answer 5

u in Nt=N0e^ut (/hr)

Question 6

Generation Time

Answer 6

time taken for a cell population to double in numbers and thus equivalent to the average length of the cell cycle

Question 7

Primary Metabolite

Answer 7

Directly involved in normal growth, development, and reproduction. Produced during the exponential phase

Question 8

Persister Cells

Answer 8

Good at surviving, alive, not dividing, metabolism slowed down, but they aren’t mutants

Question 9

Batch Culture

Answer 9

In a Flask. Waste builds up and can trigger the starvation phase. Only nutrients provided at the beginnings. Nutrients runs out. Cells are too crowded to get O2. Growth: lag, exponential, stationary, and decline. U- intrinsic

Question 10

Continuous Culture

Answer 10

In Chemostat. Nutrients are continuously added. and waste is being released when nutrients are added. Growth: binary fission, but cell numbers are at equilibrium. U= adjustable by adjusting nutrient rate. Exponential phase

Question 11

Chemostat

Answer 11

Complex system. used in continuous cultures. Nutrient is added and waste is released.

Question 12

Direct Cell Count

Answer 12

Counts all cells, living and dead. cells/mL. Petroff-Hauser chamber & Coulter counter

Question 13

Petroff-Hauser Chamber

Answer 13

Where you count cells that are in a grid square. Can’t use it if they are moving. Its a narrow range.

Question 14

Coulter Counter

Answer 14

Interruption of electric current as cells pass through counter. Only particulates in solution are bacteria. Count dead and alive cells

Question 15

Viable Cell Count

Answer 15

Counts only live cells. (cells that can grow) Colony Forming units/mL. Dilution and plating, filter plating, MPN

Question 16

Pour Plate

Answer 16

Sample goes in the tray and liquid goes on top of it. and it grows either in 2D or in the liquid. Thats how you classify it

Question 17

Spread Plate

Answer 17

Put diluted cultured on top of the agar. 0.1-0.2 mL max

Question 18

Membrane Filter

Answer 18

Allows large volumes to be counted (like water). Poured through and the filter has pores that are .2um, so bacteria can’t get through. and then the filter paper is left and the bacteria grows on it

Question 19

Most Probable Number (MPN)

Answer 19

Is a statistical method based on +/- growth in large numbers of test tubes at 3 different dilutions. 15 test tubes total

Question 20

Turbidity (=optical density)

Answer 20

Based on optical density measurements with a spectrometer. More cells=more light scattered=higher OD. But cell shape is different so different cell shape scatters light differently

Question 21

Biochip

Answer 21

biochips are essentially miniaturized laboratories that can perform hundreds or thousands of simultaneous biochemical reactions. Biochips enable researchers to quickly screen large numbers of biological analyses for a variety of purposes. Measure conductivity.

Question 22

Conductivity

Answer 22

Measurement of cell products depends on metabolism of cells being studies. Acid of fermentation is easy to measure with a pH electrode. More protons = lower pH

Question 23

Durham Tube

Answer 23

Gases are measured by Durham tubes. Gas collects at the bottom and then moves to the top of the mini tube in the big test tube

Question 24

Luciderase

Answer 24

ATP can be measured by this reaction. Fireflies have this. Sometimes done to see if any viable cells remain in a culture. No ATP=no metabolism= dead cells