Anaerobic respiration in yeast:
In this exercise, we will examine the effect of inhibitors and enayme specificity on the fermentation pathway employed by yeast cells. The product of fermentation, CO2, can be collected and measured as an indicator of the respiration rate. The enzyme enolase catalyzes the conversion of phosphoglycerate into phosphoenol pyruvate. This reaction is dependent on Mg ions and is inhibited by fluroide ions (sodium flouroide, NaF, percipitates Mg ions and thus inhibits the pathway). Fluoride is toxic to humans so HANDLE WITH CARE!

Construct FIVE respirometers (indentical to the enzymometer used in previous lab) and label the tubes well with a group name and the tube number. Fill a small test tube with the liquides indicated below. Slide a large test tube over the small one as far as possible, then quickly invert the assembly so that no liquid is lost. Immediately measure the length of the airspace aboce the liquid in millimeters. Place the tubes in a 37 degress Celsius water bath. The airspace should be carefully measured at 15 minute intervals for one hour.

Tube 1. 5 Ml yeast suspension, 10 mL distilled H2O
Tube 2. 5 Ml yeast suspension, 5 mL 5% glucose, 5 mL h2O
Tube 3. 5 Ml yeast suspension, 5 mL 5% glucose, 5 mL 0.01M NaF
tube 4. 5 Ml yeast suspension, 5 mL 5% glucose, 5 mL 0.05M NaF
Tube 5. 5 Ml yeast suspension, 5 mL 5% glucose, 5 mL 0.10M NaF

What was the effect of NaF on carbon dioxide production? Did the different concertrations of NaF inhibitor affect respiration?

Second part of lab

The effect of enzyme specificity on yeast respiration will be evaluated using lactose. Baker’s yeast is unable to metabolize lactose, which is a dissacharide. The enzyme that will be used in this exercise will demonstrate how a nonutilizable sugar can be enzymatically converted into a sugar that can be metabolized. Lactaid is a lactase (galactosidase) that breaks apart lactose into the monosaccharides glactose and glucose.

Construct Four Respirometers and label the tubes well with a group name and the tube number. Fill a small test tube (same directions go here as up top. Place in a 37 degree’s Celsius bath water for an hour and measure every 15mins of that hour.

Tube 1. 10 mL 5% + 5 mL yeast suspension
Tube2. 10 mL 5% glucose + 2 drops of lactaid solution (one tablet crushed into powder and added to 5 mL of water) + 5 mL yeast suspension
Tube 3. 10 mL whole milk (5% lactose) + 5 mL yeast suspension
Tube 4 10 mL whole milk (5% lactose) + 2 drops of lactaid solution (one tablet crushed inot powder and added to 5 mL of water) + 5 mL yeast suspension.

Questions on this experiment on the following post. I want post this before something happens and I accidentally delete it or something.