1 透過科學探究提升分析思維 E nhancement of A nalytical T hinking through S cientific I nvestigations Instructor: Ann S N Lau Lesson 3

2 Fermentation 發酵

3 Fermentation Make use of yeast metabolism Conversion of carbohydrates into carbon dioxide, alcohol acid, water, energy depending on the availability of oxygen

5 The life cycle of Yeast

6

7 Availability of Oxygen Aerobic respiration Undergo respiration in the presence of oxygen Anaerobic respiration Undergo respiration in the absence of oxygen

8 Aerobic respiration In the presence of oxygen: C 6 H 12 O 6 (Sugar) + O 2  Pyruvate Pyruvate  CO 2 + Water + Energy (ATP) Glycolysis + Pyruvate oxidation + Krebs cycle Krebs cycle: a series of enzymatic reaction in living cells that make use of oxygen in cellular respiration

Aerobic respiration Nucleus Mitochondrion Oxygen Sugar Pyruvate Inside mitochondrion CO2 + Water + Energy (ATP) Yeast cell

10 Anaerobic respiration In the absence of oxygen: C 6 H 12 O 6 (Sugar) + O 2  Pyruvate Pyruvate  CO 2 + Ethanol

11 The use of Fermentation in Daily Life

14 Beer Water + Starch source (malted barley) + Yeast + flavoring Carbon dioxide + Ethanol Anaerobic respiration of yeast

16 In biotechnology…… Yeast fermentation Production of proteins, e.g. insulin, human growth hormone, etc. Short-life cycle Secrete into the culture medium OR Stored inside the cell From Hong Kong Institute of Biotechnology Ltd.

17 Think…… Design an experiment to investigate the effect of yeast fermentation in bread dough

18 Materials: flour and water, yeast, incubator What are the factors necessary for yeast growth? What are the products produced by yeast cells? What parameters of bread dough you would like to measure with the effect of yeast metabolism?

19 Try a different way to record your data!

Plot graph using the statistical data