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BACTERIAL NUTRITION WORKSHEET: 25 Points Name: _______________________________________________________ Date: __________________ TA’s Name: ___________________________________________________ Lab Section _____________ INTRODUCTION 1) What are the six principal elements in biological macromolecules? (1 point) Proteins, nucleic acids, amino acids, macronutrients, carbohydrates, lipids 2) For the following three biological macromolecules, name the monomer or “building block” that it is assembled from (1 point): a) Polysaccharides (carbohydrates) monosaccharides b) Nucleic acids nucleotides c) Proteins amino acids 3) First, name at least 2 types of cellular molecules for which nitrogen is needed. Secondly, define a peptone. (2 points) Proteins and nucleic acids Peptone-a soluble protein formed in the early stage of protein breakdown during digestion 4) Describe what you think it means for a bacterium to be fastidious. Write in complete sentence(s) and use your own words. (1 point) It needs specific types of food or nutrients to grow 5) Look at the formulations of the 3 broth media used. For each one, add up the total potential “energy providing” organic ingredients per liter. Include cell and tissue digests/extracts, protein sources, and carbohydrates like sugars. Exclude inorganic chemical ingredients like salts, ammonium and sulfates, and phosphate buffers. (3 points) a) Brain Heart Infusion Broth 29.5g/l b) Glucose Minimal Medium 5.42g/lc) Nutrient Broth 8g/l 6) For each of the three media in Question 5, tell whether it is a chemically defined medium or a complex medium. (1 point) a-cmplex b-complex c- complex 7) Hypothesis: State a hypothesis that addresses the ability of the three broth media to support growth of bacteria. Your hypothesis must be a complete sentence or sentences and in your own words (Plagiarism warning! Do not give a copy of a lab partner’s/friend’s hypothesis). Hint: A hypothesis should be a statement, not a question. It should be a straightforward statement that can be demonstrated to be either false or supported by evidence you collect. Example: “Bacteria with thick peptidoglycan cell walls will stain purple with the Gram stain.” Another example: “Pigs can fly.” You may consider a hypothesis that ranks the media in terms of bacterial growth potential or even that there will be no difference. You do not need to give reasoning in your hypothesis statement itself. (3 points) I think the the nutrient broth will not support growth while the glucose minimal does, along with the brain heart infusion broth. MATERIALS AND METHODS 8) Why do you think that the starter cultures of E. coli and S. agalactiae were diluted to an OD600 of 0.05 prior to inoculating the three broths? (1 point) This was done to have something to compare to as a control 9) We calibrated the spectrophotometer or “blanked it” using a separate blank tube for each of the three broths, before measuring the OD600 of bacteria grown in that broth. Why might using a separate blank for each broth be important? Describe in a complete sentence using your own words. (1 point) So we can make sure the control had no growth and seeing how much we did grow RESULTS 10) Instructions for Table 1: a. Record the OD600 for your pod’s results in the appropriate boxes (2 points)b. Calculate and record the average from the other pods in your class for each culture and broth in the lines for averages in each bacterium. (2 points) c. Provide an informative title. It should include what the values are (i.e., OD 600 absorbance readings) (1 point) Table 1:_______________________________Culture Growth___________________________________________ _____________________________________________________________________________________ Culture Brain Heart Infusion Glucose Minimal Nutrient E. coli 1.58 0.24 0.38 E. coli Average 1.54 0.2 .53 S. agalactiae 1.34 -0.01 0.16 S. agalactiae Average 1.31 -.05 .12 11) Summarize your results in a few sentences. Hints: State what you observed. Focus on the numerical differences or trends. Which organism showed greater growth in the various broths on average? Which organism appears to be more fastidious? Which broth supported greater growth? Refer to the table. Ensure your summary is in your own words and consists of complete sentences (3 points) The numerical trends are similar among broths, but among organisms, E. coli seems to grow better. The brain heart infusion had the most growth with glucose miimal having the least. The S. agolactiae seems to be more fastidious. DISCUSSION 12) Describe if your results support or do not support your hypothesis from Question 7 in a few sentences. You should refer to the evidence you collected in your sentences. Consider if the information you gathered in Question 5 helps explain your results. (3 points) I was partially correct, the Brain and heart infusion broth supported growth but not the glucose minimal or nutrient broth. The brain broth had best growth rate for both

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