The Effect of Different Substrates on the Rate of Respiration on Yeast (Saccharomyces cerevisiae).

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The Effect of Different Substrates on the Rate of Respiration on Yeast (Saccharomyces cerevisiae)

What are the substrates being used?

Glucose

Glucose is a monosaccharide sugar, which is a 'simple sugar' that have between 3 and 10 carbon atoms per molecule. They are sweet and all soluble in H2O. It has the chemical composition C6H12O6. Glucose is a white crystalline solid but is less sweet then ordinary table sugar. Powdered dry glucose exists mainly in straight chain form. However, when glucose molecules are dissolved in water, two different ring structures are formed. See picture.

Fig 1

These ring structures are more stable in solution, so that, at equilibrium, almost all of the molecules are present as rings, with the straight chain form being a relatively short-lived intermediate. The structures of ?-glucose and ß-glucose differ only in the position of the -OH and -H groups attached to carbon atom number 1.

Lactose

It is formed by condensation reactions (where water is removed) between two monosaccarides, glucose and galactose. This allows an O2 bridge to form between the two molecules, holding them together forming a disaccharide. This is called a gycosidic bond. It consists of