D-Day 2009 (Denaturation Day)

Hi all,

Today, both classes examined how enzymes denature, or lose their shape, when they are exposed to pH or temperatures outside of their comfort zone.  Anything that interferes with the delicate molecular structure of an enzyme can denature it, ruining them!  One interesting thing about denaturation is that it's irreversible.  If you had taken the enzymes that you heated up to 80C in your lab and cooled them down to room temperature again, you'd still see no reaction - the enzymes were cooked for good.

This has a lot of practical applications - for example, when you cook your food, you're applying intense temperature and kinetic energy to any bacteria hanging out on the food.  Their enzymes denature, the bacteria die, and when your food cools down to a reasonable temperature to eat, the bacteria are dead - for good.  Phew.

Here is the enzyme simulation we used in class today - it's pretty helpful so come back to it for review: Enzyme Substrate Simulator

Homework
R6 - quiz tomorrow on 6.1 (digestive system).  Please also make a note of doing 6.1.4 for yourself - look up three enzymes and be able to name their source, substrate, and optimal pH and temperature for activity.  Amylase and pepsin are two good ones to start - the third enzyme you can pick.

R4 - continue to work on assessment statements.

I apologize to everyone, but I'm having some technical difficulties so I won't be able to post your lab data until tomorrow.  You can expect it by 5:00 tomorrow night.

Prokaryotes are EVERYWHERE

Did you know that humans, on average, have about three pounds of E.coli and other bacteria living in their gut?  Considering that most bacteria are fewer than 10 micrometers in length and have a weight to match, that's a lot of bacteria!

Today, in R4, groups of students worked to debrief a textbook reading about prokaryotes and answer the question of how single-celled bacteria survive.  You should now be able to draw and label a diagram of E. coli, one of the most abundant prokaryotic species, and annotate the diagram with the functions of each of the major structures.

The textbook diagrams, however, are misleadingly clear.  In reality, the parts of E. coli aren't quite so easy to pick out.  But all the parts we discussed are there - check it out:

Homework
Your assignment is to answer the questions below about this particular prokaryote.  Use looseleaf or an index card.

1. Determine the length of this prokaryote using the scale bar.  Show your workings.
2. Identify the structures labeled I, II, III, and IV.
3. Explain how I, II, III and IV enable the prokaryote to live.

This is due Tuesday for R4 and Friday for R6.  Remember that R4 has a short quiz tomorrow.