Growth/Division Flashcards
What does cellular growth refer to?
When the group divides and becomes greater in number.
What is binary fission?
○ Cell first grows a little in size, once it’s double it will split into two daughter cells.
The mother cell is no longer, it’s in parts of the daughter cells
What is the whole process of binary fission?
- One chromosome eventually ends up as two copies
- it grows a little and then replicates it’s chromosomes
- When it’s splitting a septum is formed and each side has identical chromosomes
- Then it splits & is genetically the same
What are the types of unequal cell division?
- Simple Budding
- a little bud appears, grows and then pops off into a new cell - Budding from a hyphae
- the cell makes a long structure called a hyphae and a bud comes off at the end. - Cell division of a stalked organism
- A daughter cell pops off of stalked org & a flagella takes the daughter cell away - Polar growth without differentiation of cell size.
- The bacterium only grown on one side and then pops off (in normal, both sides are growing)
What is confluent growth?
The colonies on a plate are so close together that the grow into a mat
What are the phases of bacterial cell growth in a CLOSED system?
Lag phase
Log / exponential phase
Stationary phase
Death phase
What characterizes the lag phase?
The cells are not yet multiplying as they begin to sense the conditions around them.
What are the characteristics of log / exponential phase?
The cells are actively feeding and dividing.
At about the mid point here they are dividing optimally.
In the later stages the media starts to experience:
- Exhaustion of available nutrients
- Accumulation of inhibitory metabolites
- Exhaustion of space
What are the characteristics of the stationary phase?
Cells are still active, but no longer dividing (no net change in living cells)
Secondary metabolites are produced
Are secondary metabolites necessary for survival?
Not necessarily. The cell can live and function without them.
However, not having them can lead to long-term impairment of the organism’s survivability.
What are the characteristics of the death phase?
The amount of bacterial cells dying is higher than those growing/living.
What are the characteristics of bacterial growth when in an OPEN system?
The cells can stay in the exponential phase (or some other phase)
Continuous culture can be created using a chemostat
Fresh medium is put in and spent medium is taken out
What are the steps in the cycle of producing a biofilm?
- They find a place they like and become sessile
- They form microcolonies
- they form a sugar coat around their colony to prevent dehydration and to help protect them
- The colony continues to grow and other bacteria / algae / etc. stick to them.
- When it gets too big, a piece will break off or even individual cells will regrow flagella and swim away
- This restarts the process over again
What is a floating biofilm called?
A pellicle
What are growth factors?
Organic compounds needed specifically by certain microbes that are not required by others
ex. vitamins, certain amino acids
