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increase in # of cells, not cell size.
Physical requirements for cell growth
- C, N, S, P,
- trace elements
- Organic Growth Factors.
Cold loving microbes
- Psychrophiles - minimum grow at 0 C, optimum at 15 C
- Psychrotrophs - Grow at 0C, optimally at 20-30 C
Moderate temp loving microbes
- Mesophiles - optimum growth at 25-40 C
- Most common tyme of microbes.Spoilage and disease organisms.
Heat loving microbes
- Thermophiles - grow optimally 50-60 C
- Hyperthermophiles - grow optimally at 80C or greater
What is the name of bacteria that grow in acidic envirnoment?
- Acidophiles - pH 0-3
- Most bacteria grow between pH6.5-7.5 (neutral)
- In hypertonic solution - water leaves the cells causing plasmolysis - shkrinkage of cytoplasm
- In Hypotonic solution - water moves into the cell causing lyses of the cell.
Salt loving micrboes
- Extreme and obligate halophiles - require high sal concentration in order to grow
- Facultative halophiles - do not require high salt, but can grwo in 2% salt concentration.
- Trace elements
- Organic Growth factors
- most abondant in the cell
- Used to make structural organic molecules and energy rich molecules
- 14 % of dry weight
- Found in amino acids, proteins, DNA, RNA, ATP
- Most bacteria dicmpose prtoein to get N
- Found in R group of amino acids and the vitamins
- Also necessary for synthesis fo DNA and RNA
- 2 %
- Found in DNA, RNa, ATP, and phospolipid membrane
- Inorganic element required in small amounts
- Usually needed to serve as enzyme cofactors
require oxygen to live. O2 fianl electron acceptor
are aerobic, btu grown only when oxygen concetreates are lower than that found in air.
use oxygen when present, but are able two grow via fermentation when oxygen not present.
- unable to grow when oxygen present
- use oxygen atomsalready present in cellular molecules.
cannot use oxygen for metabolism, but tolerate it fairly well.
Toxic forms of oxygen
- Singlet Oxygen
- Superoxide free radicals
- Peroxide anion
- Hydroxyl radical
- O2 boosted to higher energy state than normal
- Estremely ractive. Presten in phagocytic white blood cells.
Superoxide free radicals
- O2.- =O2 with unpaired electron, steals electron from neighboring molecules and turn them into free radicals.
- Neutralized by superoxide dismutase to produce H2O2 and O2
O22- combine with 2 protone to form O2 and H2O2 is than neutralized by catalse peroxidase to form water
- Ionizing radiation form hydorxyl radicals react with DNA and damages cells.
Organic growth factors
- cells cannot make tham, need to get from outside.
- ex. vitamins
Chemically definde media
- exact chemical compasition is known ( Energy, C, N, S, P, growth factors
- Fastidious oragnisms grow on this type of media mainly autotrophic bacteria - CO2 carbon source
- don't know exactly what's in it
- Used to grown heterotrophic bacteria and fungi (organic carbon source)
- Peptons- brokendown proteins
anaerobic grwoth media heated to drive off O2
- Inhibits the growth of paricular microbes
- ex. 7% NaCl
visual differences between groups of microbs.
selective agains G+ bacteria, and differential on the basis of lactose fermentation.
Encourages growth of desired microbes but not others, so it is also selective.
called a colony-forming unit (CFU)
Short term storage
Long term storage
- Deep freezing in a suspending liquid (cryopreserving agent is added)
- preserves for several years
freez drying, added cryoprotectant - preserved for many years
time required for a cell to divide
Lag phase of growth
- Inoculate bacteria, prepare for growth
- cells metabolicly active but do not divide.
bacteria growth at absolute max it can grow
bacteria slow down due to toxic by product, number of new cells grwoing is eqqual to number fo cells dying off.
More death, than division.
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