Lecture%2015

Lecture%2015 - Temperature Temperature B. Enzymes must be...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Temperature
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Temperature B. Enzymes must be active and balanced Cell needs many enzymes to function Cell needs conditions to permit activity of each essential enzyme in the right balance with all others
Background image of page 2
1. Each enzyme has its own temperature limits a) If temperature is too low, rate decreases In rare cases, denaturation may occur if temperature is much too low b) If temperature is too high, rate increases and may get out of balance with other enzymes Very high temperatures almost always cause denaturation
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2. The most temperature-sensitive enzyme or pathway usually sets the temperature limit for growth or survival under the given conditions The precise temperature limits for growth will depend on the particular incubation conditions because the conditions determine which enzymes are necessary for growth Not all enzymes are stopped when growth is halted by the denaturation of the most sensitive enzyme required for growth
Background image of page 4
3. Not all enzyme activities go on at every temperature within the range permissible for growth To prevent spoilage or to prevent toxin production, you may not need to keep food outside of temperature range for the particular enzymes of concern Example: The range for S. aureus growth is 7-48ºC, while the range for S. aureus enterotoxin synthesis is 10-46ºC
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4. Temperature extremes disrupt enzyme balance, and cells in unbalanced growth are more susceptible to death The less metabolism is going on, the less damage is done when an enzyme is inactivated Very low temperatures increase survival because metabolic activities greatly reduced Growing cells are easier to kill than are non-growing cells
Background image of page 6
Harmful Biological effects 1. Exposure to temperatures greater than T max for growth a) Loss of membrane integrity leading to loss of key nutrients and breakdown of key surface structures-death
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 22

Lecture%2015 - Temperature Temperature B. Enzymes must be...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online