Mmg Lab 9

Front 1

Define binary fission.

Back 1

-most common means of reproduction by bacteria
-once cell divides into two, split to make four, which become eight, etc

Front 2

Define lag phase.

Back 2

-adjustment period of bacteria in new medium/environment
-no cell number growth, but increase size/girth
-increase rate of RNA, DNA, and ribosome production

Front 3

Define logarithmic phase.

Back 3

-cell numbers increase in exponential growth
-doublings occur at regular intervals
-the period of balanced growth in which the rates of synthesis of importnat componenets are maximized for condistions
-all units increase in equal intervals per time
-most cells viable
-largest sized cells due to largest number of ribosomes and proteins

Front 4

Define total cell count.

Back 4

-the sum of all living and dead cells

Front 5

What are factors that affect the length of lag phase?

Back 5

-status of transferred cells
-previous environment
-number of viable cells transferred

Front 6

Define Viable Cell Count.

Back 6

-Only the living cell count

Front 7

When are cells most vulnerable to chemicals and antibiotics?

Back 7

-logarithmic phase

Front 8

What is the stationary phase?

Back 8

-growth rate begins to taper off
-growth and death rates are equal
-bacterial growth reaches a plateau
-cells become smaller and old, nutrients become limiting and wastes accumulate

Front 9

What is the death phase?

Back 9

-lack of nutrients lead to starvation
-dead cells lyse which can serve as nutrients for other cells

Front 10

What is the difference of solid media verses liquid in growth?

Back 10

-solid medium has tightly packed cells leading to quicker use of resources
-outside of colonies are in exponential growth while center is in death phase

Front 11

What is diauxic growth?

Back 11

-growth of microorganisms in two phases

Front 12

What is cryptic growth?

Back 12

-cells in center of colony die releasing nutrients that viable cells can use

Front 13

What is catabolite repression?

Back 13

-breakdown of nutrients is inaccessible
-use of enzyme is needed for growth and can exhibit how a microorganism uses diauxic growth

Front 14

What are two common ways to measure bacterial culture growth?

Back 14

-plate count
-optical density

Front 15

What is a plate count?

Back 15

-using a plate or liquid culture of bacteria
-bacteria plated, incubated, and cells grown after 24 hours are counted for viable cells
-expensive and time consuming

Front 16

What is the optical density method of bacterial count?

Back 16

-measure of turbidity
-inexpensive and quick
-accuarate readings for log phase
-innacurate otherwise because of dead cells refracting light as well

Front 17

What is generation time?

Back 17

-doubling time
-the time required for the formation of two new cells from one cell
-dependent on the cells genetic ability to carry out catacolic and anabolic processes

Front 18

How do you find the generation time from a graph?

Back 18

-draw a straight line in log phase
-find any OD number on x-axis and draw line to y axis (mark as beginning value)
-double this time and find on y axis (mark end time)
-the distance between these two points horizontally is the doubling time