Microbio Ch. 5 Flashcards
1
Q
Starts on “Terms” slide
A
.
2
Q
Growth
A
Increase in the number of cells.
3
Q
Binary Fission
A
Division of bacterial cell into two equal cells
4
Q
Budding
A
unequal division of cell (Found in Yeast and some bacteria)
5
Q
Septum
A
Partition between dividing cells (pinch point)
6
Q
Generation Time
A
- Time required for cells to double in number
- Depends on nutrition, genetic factors and temperature
- (i.e. Escherichia Coli = 20 minutes)
7
Q
Steps of Binary Fission
A
- Young cell at early phase of cycle
- Parent cell prepares for division by enlarging its cell wall, plasma membrane, and overall volume
- DNA replication then starts
- Septum begins to grow inward as the chromosomes move toward opposite ends of the cell. Other cytoplasmic components are distributed to the two developing cells
- The septum is synthesized completely through the cell center, creating two separate cell chambers
- At this point, the daughter cells are divided. Some species separate completely as shown here, while others remain attached, forming chains, doublets, or other cellular arrangements
8
Q
How do bacteria grow and divide?
A
They divide by binary fission, NOT mitosis or meiosis.
9
Q
Biofilm
A
- Community of bacteria and other organisms congregated into a mass of cells protected by slime layers - complex, interactive community
- Most microbes grow attached to surfaces (sessile) rather than free-floating (planktonic)
10
Q
Biofilm formation
A
- Planktonic cells attach to a conditioned surface
- Secretion of extracellular polymeric substance (EPS)
- Ubiquitous in nature
11
Q
Extracellular polymeric substance (EPS/Slime)
A
- Protects microbes from harmful agents (UV light, antibiotics, antimicrobials)
- When formed on medical devices, such as implants, often lead to illness
- Sloughing off of organisms can results in contamination of water phase above the biofilm such as in a drinking water system
12
Q
Exponential Growth
A
- Growth of a microbial population over a specfic time interval
- Data can be plotted as arithmetic or logarithmic curve
- Arithmetic is actual cell numbers
- Logarithmic is the logged value of actual cell numbers to get a prediction of what number it will be in the future
13
Q
Know difference between arithmetic and logarithmic curves and when to use them.
A
- Use logarithmic for extrapolating
- Arithmetic when you want the actual numbers
14
Q
Growth Phases
A
- Lag phase: Genes turned off due to not having substrate, but then suddenly getting introduced to a plethora of substrate and the system telling itself to turn
- Exponential phase: Growth until resources run out
- Stationary phase: Nutrients and resources start to run out, water becomes scarce, waste products build up in the culture
- Death phase: Environment becomes more toxic and cells begin
15
Q
Continuous Culture
A
- An open system microbial culture of fixed volume
- Continuous flow of media coming in and a bottom flow of waste leaving the media
