CH 6 Flashcards
Cell Division
- when unicellular organisms (bacteria) divide they are reproducing
- when multicellular cells divide they are replacing dead or damaged cells or growing.
Prokariotic Reproduction
Asexual Reproduction
-99% of time in unicellular organisms
- produces offspring
-genetically identical to parent cell
-no partner involved
- no exchange of genetic material between
cells
Common forms of Asexual reproduction
- In unicellular organisms, Budding and
Binary fussion
Budding
(Typically seen in yeast)
- New smaller offspring (clone) “buds” from
the original cell (parent)
- breaks away from parent cell, then grows
to the mature size
Binary Fission
-Original parent cell grows in size, including
replication of cellular content.
- cell splits into TWO identical cells, typically
seen in bacteria
Conjugation
.1% chance
- sexual reproduction in microbes
- rare, 2 bacteria reproduce sexually
- one cell makes copy of its chromosome or plasmid and transfers the copied DNA
- exchange of genes
- Resulting in offspring or genetically different cell from its parent
Life Cycle of Prokaryote
4 Microbial Growth Phases
- bacteria introduced to new mediums ideal for growth, they go through 4 phase
- Lag, Log, stationary, death or decline
Lag Phase
-Bacteria adapting to new conditions, no reproduction, little metabolic activity
Log Phase
- Peak reproductivity and metabolic
activities
Stationary Phase
- # of new cells are produced offset by # ofcells dying, nutients begin to decline and
waste begins to accumulate
Death Phase
- Conditions inhospitable,nutrients deplete,
waste inhibits growth/reproduction. Cells
die, population declines
Physical Influences on Growth
Most bacteria grow best under moderate condition like
- Ph near 7
- low to no salt
- temperature near 37C
Growth preferences
PH
- Acidophile
- Alkaliniphile/Alkalophile
Growth Preferences
Salt
- Halophile
- Most fermented food
Growth Preference
Temp.
- Psychrophile
- Mesophile
- Thermophile
- Extreme thermophile
