Question | Answer |
Name the 5 classifications of microorganisms on the basis of preferred temperature range. | Psychrophiles, psychrotrophs, mesophiles, thermophiles, hyperthermophiles |
What's the preferred temperature of psychrophiles? Psychrotrophs? Mesophiles? Thermophiles? Hyperthermophiles? | very cold; cold; moderate; hot; very hot |
What is the temperature range of psychrophiles? | -10 to 20 degrees Celcius |
What is the temperature range of psychrotrophs? | 0 to 30 degrees Celcius |
What is the temperature range of mesophiles? | 10 to 50 degrees Celcius |
What is the temperature range of thermophiles? | 40 to 70 degrees Celcius |
What is the temperature range of hyperthermophiles? | 65 to 110 degrees Celcius |
how does temperature effect growth rates? | bacteria grow poorly at the high and low temperature extremes within their range. |
What happens to bacteria above their optimum growth temperature? Why? | rate of growth drops off rapidly; high temperature has inactivated necessary enzymatic systems. |
What happens to microbes at low temperatures? | Their microbial reproductive rates decrease |
What are the toxic forms of oxygen that certain organisms have to produce enzymes to defend against? | Superoxide free radicals (O2 -) and peroxide anion (O2^2-) |
What enzyme is produced to combat the toxicity of superoxide free radicals? How does it do so? | superoxide dismutase (SOD); breaks it down into hydrogen peroxide and oxygen.
O2- + O2- + 2H+ > H2O2 + O2 |
What is the most common enzyme produced to combat the toxicity of the peroxide anion found in hydrogen peroxide? How does it do so? | catalase; breaks it down to water and oxygen. 2H2O2 > 2H2O + O2 |
What is another enzyme that breaks down the peroxide anion found in hydrogen peroxide? How does it differ from the enzyme catalase? | Peroxidase. No oxygen is produced from its reaction. H2O2 + 2H+ > 2H20 |
Which organism produces catalase and superoxide dismutase? | Aerobe |