Chapters 6, 5, 8 Flashcards
(131 cards)
What does Growth mean when talking about bacteria cells?
increase in number
not size
What 3 things are the Cardinal Temperatures of Bacterium?
- Minimum Temperature
- Optimum Temperature
- Maximum Temperature
(temps they can reproduce at)
Do freezing temps denature bacteria, if so what does it denature, if not, what do cold temps do to bacteria
freezing bacteria does Not denature bacteria.
Freezing inhibits growth but once they are no longer frozen they begin reproducing again
What do you call bacteria that loves the cold temps?
Psychrophiles
What is the most common type of bacteria, the type we’d probably get sick from?
Mesophiles
Name the bacteria that love hot temps (not extreme hot hot temps)
Thermophiles
Name the bacteria that love EXTREMELY HOT HOT temps
Hyperthermophiles
What 3 things could very high temperatures denature in bacteria?
- enzymes
- ribosomes
- membranes
Around what temperature in F would be considered the “Danger Zone” where rapid growth of bacteria and sometimes production of toxins takes place within food?
between ~60 degrees F and ~120 degrees F
Who has more genes, humans or rice?
rice (almost double our gene count)
In general, are Hypotonic environments harmful to bacteria?
Osmotic Pressure
No
What happens to bacteria in a hypertonic solution?
plasmolysis
(shriveling, pulling away from cell wall caused by loss of water through Osmosis)
inhibits bacterial growth
Some bacteria can survive high osmotic pressure by increasing the solute concentration of their _________
cytoplasm
What is the name of the type of bacteria that can WITHSTAND high osmotic pressure exerted by salt?
(hypertonic)
Halotolerant
Name 3 ways we use hypertonic environments to preserve food
- Drying (ex: dried fruit)
- Salting
- Sugaring
What do Halophilic bacteria REQUIRE to survive?
high concentrations of salt
Bacteria that live at High or Low pH have mechanisms to keep the pH of their cytoplasm around _______
neutral
Different bacteria types have different Oxygen requirements.
True or False?
true
Where is the highest concentration of oxygen found in a lab tube, at the top or at the bottom?
highest O2 concentration at the top
What is the most temperature sensitive part of a bacterial cell? (which will denature first?membrane, enzymes, or ribosomes?)
- enzymes are most temperature sensitive
- then the membrane will melt
- 3rd the ribosomes will denature
When you slow the growth of bacteria by lowering temps to freezing but don’t kill it, this is called ______ __________
growth inhibition
All human pathogens are which type of bacteria (pertaining to reproduction in temperatures)?
Mesophiles
What type of bacteria spoil our food?
remember when you refreeze previously thawed food
Psychrotrophs
How come we can still get sick from food that has gone bad if we cook it at high temps, shouldn’t that kill the microbes?
toxins produced by the bacteria are not heat sensitive so they are still in meat after it’s cooked