Information
• Don’t forget your Microworlds Project!
– Protist cultures on back counter?
– Yeast cells fr/ today’s lab (try methylene blue)
– Catch fruit flies? (Eyes are easy to study)
– You will have a lot of time to work on microworlds
today & in lab 9
– Making an Informal Lab Report on an experiment
you’re designing today!
– Due at start of week 9 (Meiosis Lab)
INFORMAL LAB REPORT:
• See my web page for instructions.
With your lab group:
– From your observations, make a
question about some aspect of
fermentation.
– Come up with a hypothesis to answer
your question.
– Design an experiment to test your
hypothesis.
– Perform the experiment, collect your
results.
INFORMAL LAB REPORT:
• As an individual:
– Fill in the Informal Lab Report Worksheet (see Lab Report
link). All answers must be your own work!
– Turn it in by week 9, normally in 2 weeks. For point totals,
see the lab syllabus.
– Pay attention to how to write up a scientific paper, how to
make a scientific figure, and how to write a scientific
reference, as these must be followed for full credit.
– There are directions for all three of these in the appendix of
the lab manual, although the guide for writing a scientific
paper seems to apply more for a Formal lab report than an
Informal one.
Lab 7: Fermentation & Cellular
Respiration
Cellular respiration is only covered in the
reading today.
Part 1: Alcoholic Fermentation
• Glucose
Alcohol + CO2 + ATP
Part 1: Alcohol Fermentation
• Yeast + corn syrup
CO2
Ex. 1: Alcohol Fermentation
• Test the effect of different amounts of yeast
suspensions on fermentation.
• I will demonstrate setting up the fermentation tubes.
Note error in the lab manual, it tells you how many
ml to add, but the tubes vary & you must fill the
tubes to get all the bubbles out!
• Use bubble size to measure your fermentation.
• Take care to distinguish a bubble from an area where
the yeast has settled out of solution.
• When done, clean WELL 4X or more with water.
Ex. 2: Alcohol Fermentation
• Design your own fermentation experiment
• Ask a question and make a hypothesis
• You can vary one independent variable:
– Different sugar substrates & other substrates
– pH buffers (do not use pH 11!)
– Temperatures
– Saline (salt) solutions
• Remember to keep constant
all other variables!
Ex. 2: Alcohol Fermentation
• Think about what you are doing!
• If you add 1 ml of 10% NaCl to 10 mls, you have
diluted it to 1% or nearly isotonic.
• If you add room temp yeast and sugar together and
then put them on ice, it will ferment immediately
and while the temp slowly cools.
• Do not use saccharin, it is a mixture of saccharin and
D-glucose.
• Do not use pH 11 or we will all need goggles.