Temperature Flashcards
What are cardinal temperatures?
○Cardinal temperatures are the minimum, optimum, and maximum growth temperatures for microbes (Willey, et al., 2011, pp.163-181).
○They are not rigidly fixed, and can be affected by other environmental factors like pH and nutrient availability (Willey, et al., 2011, pp.163-181).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Define psychrophile.
○Psychrophiles are microbes which grow in cold temperatures and have growth range between 0 to 20 and growth optimum temperature of 15 (Willey, et al., 2011, pp.163-181).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
What metabolic and structural adaptations for extreme temperatures do psychrophiles have?
○Psychrophiles are microbes that grow at low temperatures, between 0 to 20 (Willey, et al., 2011, pp.163-181).
○At low temperatures, the cell membrane can lose fluidity and pack close together (Willey, et al., 2011, pp.163-181).
○To prevent this, psychrophiles have cell membranes composed of high levels of unsaturated fatty acids (Willey, et al., 2011, pp.163-181).
○The unsaturated fatty aids have kinks in their hydrocarbon chains, which increases membrane fluidity by preventing close packing of phospholipids in bilayer (Knapp et al. 2022).
¤Reference: Knapp, B.D., Huang, K.C. (2022) ‘The effects of temperature on cellular physiology’, Annual review of biophysics, 51, 499-526.
Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Define psychrotroph.
○Psychrotrophs are microbes that grow from 0 to 35 (Willey, et al., 2011, pp.163-181).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Define mesophile.
○Mesophiles are microbes that grow in normal temperatures and have minimum temperature of 15 to 20, and optimum growth temperature of 20 to 45 (Willey et al., 2011, pp.163-181).
Define thermophile.
○Thermophiles are microbes that grow best at higher temperatures and have optimum growth temperature of 55 to 65, and minimum growth temperature of 45 (Willey, et al., 2011, pp.163-181).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Define hyperthermophile.
○Hyperthermophiles are microbes that grow at high temperatures and have optimum growth temperature of 85 to 113, and growth minimum of 55 (Willey, et al., 2011, pp.163-181).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
What metabolic and structural adaptations for extreme temperatures do psychrophiles have?
○Thermophiles are microbes that grow at high temperatures, between 45 to 65. (Willey, et al., 2011, pp.163-181)
○At high temperatures, cell membrane becomes more fluid and is disrupted, which causes leakage of cell contents (Willey, et al., 2011, pp.163-181).
○To prevent this, thermophiles have more branched and more saturated membrane lipids which have a higher molecular weight, causing tighter packing of phospholipids in bilayer and increasing their melting points, making the membrane lipids more temperature stable (Willey, et al., 2011, pp.163-181).
○Thermophiles also have heat-stable enzymes and proteins, that have hydrophobic interiors that are highly organised, and also contain more hydrogen and noncovalent bonds (Willey, et al., 2011, pp.163-181).
○Polypeptide chains in proteins are also less flexible and more heat stable due to high levels of amino acids (Willey, et al., 2011, pp.163-181).
○Chaperone proteins stabilise proteins and help them to fold (Willey, et al., 2011, pp.163-181).
○DNA of thermophilic bacteria is stabilised by nucleoid-associated proteins (Willey, et al., 2011, pp.163-181).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
