Learning outcomes Explain the importance of asepsis in the manipulation of microorganisms

Asepsis Asepsis Aseptic techniques absence of unwanted microorganisms Any measure taken during a biotechnological process to prevent contamination by unwanted microorganisms

The importance of asepsis Unwanted microorganisms Compete with the culture microorganisms Reduce the yield of useful products Cause spoilage of the product Produce toxic chemicals Destroy the culture microorganism or its products.

Methods to maintain asepsis Ensure all fermenters and attachments are sterile Cleaning with pasteurised steam Chemical sterilisation Sterilise all liquids, solids and gases that enter the reaction vessel Maintain a pressure difference between the air in the room where fermentation is taking place and outside Maintains a steady airflow out of the room Ensure culture of microorganisms is pure Ensure the workers do not introduce unwanted microorganisms from their skin.

Guidelines for Quantitative Experiments Line graphs Straight lines should join points. A smooth curve is only drawn if there is reason to believe that intermediate values fall on the curve. The independent variable should be plotted on the horizontal axis (x) and the dependent variable plotted on the vertical axis (y). Axis labels should be stated horizontally and in lower case, using SI units. Axes should have an arrow end when there is no scale. If the origin (0,0) is not included in a printed graph, the axis should be broken. Points should be plotted with encircled dots or saltire crosses ( x ). When multiple curves are being plotted, vertical crosses ( + ) can be employed. If a graph shows more than one curve, then each curve should be labelled, at the end of the line, to show what it represents.

Guidelines for Quantitative Experiments Line graphs Straight lines should join points. A smooth curve is only drawn if there is reason to believe that intermediate values fall on the curve. The independent variable should be plotted on the horizontal axis (x) and the dependent variable plotted on the vertical axis (y). Axis labels should be stated horizontally and in lower case, using SI units. Axes should have an arrow end when there is no scale. If the origin (0,0) is not included in a printed graph, the axis should be broken. Points should be plotted with encircled dots or saltire crosses ( x ). When multiple curves are being plotted, vertical crosses ( + ) can be employed. If a graph shows more than one curve, then each curve should be labelled, at the end of the line, to show what it represents.

Worksheet: Plotting graphs Answer q1 on the sheet. (Line Graphs) Worksheet provided separately

Marking your graph Each point is equal to 1 mark 1. Line graph with plots joined by straight lines OR appropriate line/curve of best fit 2. x and y axes scaled correctly: equidistant intervals on both axes. 3. x axis labelled: Time (s); y axis labelled: Volume of gas collected (cm3) 4. all points plotted correctly 5. lines labelled at the end OR an appropriate key used to include units (Concentration of H2O2 (mol dm -3))

Worksheet – graph skills Q2. Using graphs in calculations Q3. Describing graphs Q2 Student is correct – although gradient calculation makes it about 48, not 50 in 20 seconds.

Quantitative Experiment The aim of the task is to determine the effect of temperature on the activity of two preparations on lipase: free in solution and immobilised in alginate beads

Exam Practice – Unit 5 questions