hello, i am a junior in college, and i have a few questions. i am taking a biology course (not good at it) and i am lost. i had to do a lab last week exploring the process of ethyl alcohol fermentation. specifically, testing the ability of yeast cells using different kinds of sugars as fuels for fermentation. The three sugars- glucose, sucrose, and lactose.
I was in a group and literally had not one clue what was going on, all i did was count bubbles. can you please explain to me what the heck this is ... i have to write a 5 page formal report on this and i have no idea how to start.
Yeast respires anaerobically to produce ethyl alcohol and carbon dioxide (or aerobically to produce carbon dioxide and water. The bubbles you were counting were carbon dioxide - the more bubbles, the more respiration. Yeast uses sugars as a substrate for respiration. Glucose is the usual substrate and should work well. Sucrose consists of glucose and fructose (fruit sugar) and should also work well, although it will need to be broken down into glucose and fructose by enzymes in the yeast before it can be respired. Lactose should not be so successful, because it is found in milk, which yeast does not encounter in nature, and so it is unlikely to have enzymes to break it down into glucose and galactose. A small amount of natural breakdown in the milk will mean that there will be SOME respiration, though.