Test 3 Chapter 9 Study Guide Flashcards
Daughter cells
Two completely identical cells formed as a result of binary fission
Binary Fission
Most common method of prokaryotic division. Replicates DNA. Center constricts forming two daughter cells
FtsZ Protein
Directs cytokinesis and cell division in prokaryotic cells
First step of Binary fission
FtsZ forms a Z Ring on the cytoplasmic membrane
Second step of Binary fission
Z ring is anchored by FtsZ-binding proteins defining the division plane
Third step of Binary Fission
Additonal proteins added to z ring to form a divisome
Final step of Binary Fission
Divisome leads to peptidoglycan production and septum formation
Septum Formation
Forms new cell wall between the daughter cells at the end of binary fission
Generation (doubling) time
Time it takes for the population to double through binary fission
Formula for generation time
Number of cells = Starting cells x 2^number of generations
Bacterial Growth Curve
Growth patter of microorganisms in a closed culture NO NUTRIENTS ADDED OR WASTES REMOVED
Lag Phase
Immediately after adding bacteria to culture. No increase in number of living bacteria. Bottom of the curve.
Log Phase
Exponential increase in number of bacteria cells. Rise on graph. Constant growth. IDEAL STAGE FOR RESEATCH AND MOST SUSCEPTIBLE TO ANTIMICROBIALS/DISINFECTANTS.
Stationary phase
When New cells = dying cells. Plateau on graph. Endospores may form
Death Phase
Dying cells > new cells. Down slope of graph. Persisters may remain.
CFU/mL – if count 50 colonies on 1:10,000 dilution (10^-4)
CFU/mL = 50 * 10 * 10,000 = 5,000,000 = 5.00 x 10^-6 CFU/mL
Serial Dilutions
1mL from original culture, added to 9 mL broth - makes a 1:10 dilution
Biofilm
Ecosystems of bacteria. Many different bacteria hanging out.
Bacteria Perks of Biofilm
Highly structured communities, selective advantage to bacteria. Resist antimicrobial, resource sharing, effective waste removal.
Biofilm Structure
Embedded in a matrix with water channels interspersed. Allows nutrient, waste, gas movemement.
Matrix of extracellular polymeric substances (EPS)
Polysaccharides and other macromolecules as a gel-like substance that holds biofilm together. Gives structure and integrity.
Quorum Sensing
Cells coordinate activity in response to environment.
Autoinducers
Communication molecules involved in Quorum Sensing
Great Oxygenation Event
Early atmosphere was anoxic (no oxygen) Cyanobacteria increased oxygen in atmosphere killing most anaerobes.
Reactive Oxygen Species (ROS)
By products of aerobic cellular respiration. Powerful redox reactions.
Anaerobic ecosystems
Oxygen free environments - Deep in Earth’s crust, Marshes, Bogs, Sewers, in the body.
Obligate Aerobe
Needs oxygen to survive. Mycobacterium tuberculosis
Obligate Anaerobe
Oxygen kills them. Lack enzymes to inactivate ROS. Bacteroides spp.
Facultative Anaerobe
Aerobic bacteria, but can survive without oxygen. Grows best with oxygen. Staphylococci spp.
Aerotolerant Anaerobe
Tolerate oxygen, some enzymes to deal with ROS. Lactobacilli
Microaerophile
Obligate Aerobes, but require a very specific amount of oxygen. Around 1-10% oxygen. Campylobacter jejuni
Obligate Aerobe in a Thioglycolate Medium (FTM test).
Bacterial cells all at the top of the tube, need oxygen
Obligate anaerobes in a Thioglycolate Medium (FTM test).
Bacterial cells all at the bottom of the tube, killed by oxygen.
Facultative Anaerobes in a Thioglycolate Medium (FTM test).
Bacterial cells mostly at the top some spread throughout tube.
Aerotolerant Anaerobes Thioglycolate Medium (FTM test).
Bacterial cells spread throughout the tube.
Microaerophile in a Thioglycolate Medium (FTM test).
Bacterial cells close to the top but not on top.
Preoxidase
Breaks down hydrogen peroxide and turns it into water. Limits damage to membrane lipids
Superoxide dismutase (SOD)
Breaks down superoxide anions generated by aerobic metabolism
Catalase
Breaks down two hydrogen peroxide into 2 water and some oxygen
pH and microbial growth at High pH
Hydrogen bonds between DNA strands are broken and lipids are hydrolyzed. pH imbalances denature proteins
Optimum pH
Most favorable pH for organism growth
Minimum pH
Lowest pH an organism can tolerate.
Maximum pH
Highest pH an organism can tolerate,
Neutrophile
Optimum growth range around pH of 7 (6-8)
Location: Neutral environments.
Acidophile
Have pumps to actively transport H+ out of the cell. Optimum Growth <5.5
Used for food fermentation.
Location: Sauerkraut, pickles.
Alkalinophile
Lipid and protein modifications. Optimum growth 8.0-10.5.
Location: soda lakes
Basic enviornments.
Optimum Temp
temp where growth rates are highest
Minimum temp
Lowest temperature where bacteria can divide
Maximum temp
Highest temperature at which growth can occur
Psychrophile
can grow at 0C but optimum is closer to 15C and rarely survive above 20C
Psychrotrophs
4C - 25C
Mesophile
Moderate Temperature between 20C - 45C
Thermophile
Like it hot 50C - 80C
Hyperthermophile
Really Hot 80C-110C
What happens to bacteria in the cold
Membranes lose fluidity (become stiff & hard). ice crystals form. Proteins denature.
Psychrophiles and Psychrotrophs (defenses)
Increased hydrophobic R groups in protein
Antifreeze proteins
Increase in unsaturated fatty acids – Harder to freeze because so fluid
What happens to bacteria in the Hot
Membranes become too fluid (melt). Proteins denature. Nucleic Acids Denature.
Thermophiles and hyperthermophiles (Defenses)
Increase in saturated fatty acids – harder to melt cause solid
Higher GC content in DNA
Additional bonds to allow protein stability
Hypotonic
pressure inside the cell greater than outside.
Net water movement into the cell
Isotonic
Equal pressure inside and outside the cell
Net water movement back and forth equal
Hypertonic
Pressure outside the cell greater than inside, net movement out of the cell.
Halo likes salt
Halotolerant organisms
Halophiles
Halotolerant organisms
Tolerate high salt, not super high salt
Halophiles
require high salt environment.
Dead Sea
Barophile
Require high pressure
