Chapter 9 - Microbial Growth

Question 1

Binary Fission

Answer 1

Bacteria and archaea most commonly engage in a process known as binary fission, where a single cell splits into two equally sized cells

Question 2

Other Less Common forms of Reproduction

Answer 2

Multiple Fission, Budding and production of Spores

Question 3

Binary Fission Step 1:

Answer 3

Elongation

Question 4

Elongation

Answer 4

Careful enlargement of the cell membrane and the cell wall, in addition to an increase in cell volume.

Question 5

Binary Fission Step 2:

Answer 5

DNA Replication

Question 6

What happens during DNA replication?

Answer 6

Prepares to have two copies of each chromosome, one for each cell

Question 7

Binary Fission Step 3:

Answer 7

Protein FtsZ initially manifests as a ring in the middle of the elongated cell. Important for the septum to form.

Question 8

Binary Fission Step 4:

Answer 8

After the nucleoids are segregated to each end of the elongated cell, septum formation is completed, dividing the elongated cell into two equally sized daughter cells.

Question 9

Closed System/Batch Culture

Answer 9

no food added, no wastes removed

Question 10

What are the parts of a growth curve for bacteria in a closed system

Answer 10

1. the lag phase 2.The exponential or log phase 3. The stationary phase, 4. The death or decline phase.

Question 11

Generation Time

Answer 11

The amount of time it takes for a population to double

Question 12

lag phase

Answer 12

Adaption period and adjusting. Length can vary greatly. They synthesize RNA, enzymes, and essential metabolites that might be missing from their new environment. Also adjustment to environment pH, temp and O2

Question 13

Shortest Lag Period?

Answer 13

Actively growing cells transferred from one type of media into the same type of media, with the same environmental conditions

Question 14

Longest Lag Period?

Answer 14

Damaged Cells

Question 15

Exponential/Log Phase

Answer 15

Marked by predictable doublings of the population, where 1 cell become 2 cells, becomes 4, becomes 8 etc. Cells are healthiest during this period.

Question 16

What is needed for Rapid Growth? What results in slower growth?

Answer 16

Rapid - optimal conditions. (Steeper Curve) Slow - Less than idea conditions.

Question 17

Log Phase equation?

Answer 17

N=N02^n

Question 18

N

Answer 18

Final Cell Concentration

Question 19

N0

Answer 19

Initial Cell Concentration

Question 20

n

Answer 20

Number of Generations that occurred between the specified period of time

Question 21

How can we represent generation time

Answer 21

g = t/n, where t is a period of time

Question 22

Stationary Phase

Answer 22

Population runs out a nutrients, or growth hindered by waste products, or physical space. At this point the number of new cells being produced is equal to the number of cells dying off or growth has entirely ceased, resulting in a flattening out of growth on the growth curve.

Question 23

What happens to cells during stationary phase?

Answer 23

The new cells that are created are smaller in size. Bacilli can become near spherical in shape. Membrane becomes less fluid. More hydrophobic on outside. Nucleoid condenses and DNA binds with DNA-binding proteins from starved cells (DPS).

Question 24

oligotrophic

Answer 24

Low Nutrient Environment

Question 25

secondary metabolites

Answer 25

metabolites produced after active growth, such as antibiotics

Question 26

Death Phase/Decline Phase

Answer 26

Last phase. Number of cells decreases predictably. Steepness depends on how fast cells lose viability

Question 27

viable but nonculturable (VBNC)

Answer 27

cells thought to be dead might be revived under specific conditions - important for pathogens

Question 28

Is 100% cell death likely?

Answer 28

No, as the cells mutate to adapt to their environmental conditions, however harsh.