Prelab 5

Prelab 5 SUGAR METABOLISM 1. What are the indicators in the phenol red medium and OF medium? (2 points) - The pH indicator in phenol red medium is the phenol red, which turns yellow below a pH of 6.8 and a deep red above pH of 7.4 - The OF medium’s pH indicator is the bromothymol blue UTILIZATION OF COMPLEX CARBON SOURCES: EXOCELLULAR ENZYMES 2. What are the end products resulting from the action of caseinase, lipase, amylase, and DNase? (2 points) - Alpha-amylase end products: alpha-amylase cleaves the alpha-1,4 linkages that join the glucose monomers in starch, so the end products will be glucose monosaccharides - Caseinase: caseinase is a protease that cleaves peptide linkages joining amino acid monomers in the protein casein. So the end products will be amino acids monomers - Lipase: lipase degrades into individual fatty acids so the end product will be monomeric fatty acids - DNAase: DNAase cleaves the phosphodiester linkages between nucleotides within a polynucleotide chain, so the end product will be nucleotide monomers. GROWTH YIELDS AS A FUNCTION OF CARBON SOURCE 3. Complete the following tables according to the information for exercise 5.4. (3 points) Assay tube Vol. 2X YP (mL) Final glucose conc. (% m/v) Vol. glucose (mL) Yeast inoculum (mL) Vol. water to a final vol. of 5 mL G1 2.5 0.5 0.125 0.1 2.275 G2 2.5 1.0 0.25 0.1 2.15 G3 2.5 2.5 0.625 0.1 1.775 G4 2.5 5 1.25 0.1 1.15 G5 2.5 10 2.5 0.1 4. Complete the following tables according to the information for exercise 5.5 (3 points) Glucose (g) Volume of 20% (m/v) glucose (mL) Buffer pH 7.0 Water to a final volume of 10 mL 0.2 1 5.0 mL 4 0.1 0.5 5.0 mL 4.5 0.02 0.1 5.0 mL 4.9 0.01 0.05 5.0 mL 4.95