Determination of the Rates and Optimal Temperature for Aerobic Respiration and Photosynthesis. Lab report

Glycolysis & the TCA Cycle Aerobic Respiration: ETC Oxygen is the terminal electron acceptor:

amount in the medium decreases!

https://courses.lumenlearning.com/boundless-biology/ chapter/oxidative-phosphorylation/ Photosynthesis: Hill Reactions Oxygen is produced by PSII: amount in the medium increases! Photosynthesis Dark conditions ≠ dark reactions!

● Hill reactions (“light reactions”) and the Calvin cycle (“dark reactions”) are interdependent – While the Calvin cycle does not directly require light, it cannot proceed in the absence of the products of the Hill reactions Effects of Temperature ● Metabolic processes in the cell are largely enzyme-dependent ● Increasing temperature increases the kinetic energy: reactions occur more quickly ● Past the optimum temperature proteins become denatured: so steep decrease in activity Yeast ( Sacchromyces ) ● Unicellular fungi containing mitochondria, but no chloroplasts:

measure aerobic respiration only ● Determine cell number using spectrophotometry:

– O.D. of 1 ≈ 1 x 10 7 cells – Use culture at 0.75 x 10 7 cells/mL Euglena ● Flagellated protozoan ● Contains mitochondria & chloroplasts:

measure both aerobic respiration & photosynthesis © Carolina Biological Supply Euglena ● Problem: if it both uses and produces oxygen, how do we interpret data from the probe? Euglena ● Problem: if it both uses and produces oxygen, how do we interpret data from the probe?

– In the dark, only aerobic respiration (oxygen use) can occur – Cover with black cloth in aerobic respiration experiment (Part B) Euglena ● Problem: if it both uses and produces oxygen, how do we interpret data from the probe?

– In the light, both processes occur: provides us with the apparent rate of photosynthesis – Must also determine rate of oxygen use by covering with cloth:

actual rate = │ rate light │ + │ rate dark │ Euglena ● Determine cell number by counting with haemocytometer: add 5 areas and multiply by 50,000 = cells/mL – Use culture at 1 .5 x 10 7 cells/mL – Remember to account for different cell densities when comparing Euglena and yeast! Data Analysis:

Amount of oxygen/unit ● Determine the µ g oxygen/unit in 2 mL sample:

O 2 / unit ( in 2 ml ) = (max. O 2 / ml) x 2 ml total units From Table 1 of Appendix E Changes with temp!

Based on maximum and minimum set on chart recorder 95 units – 5 units = 90 units Data Analysis:

Amount of oxygen/unit ● Determine the µ g oxygen/unit in 2 mL sample:

O 2 / unit ( in 2 ml ) = (max. O 2 / ml) x 2 ml total units = (5.37 μ g/ml) x 2 ml 90 units = 0.119 μ g/unit ● Use the chart to determine the change in oxygen (# units/min) At 60 O C Data Analysis:

Δ oxygen (units/min) Data Analysis:

Amount of oxygen/min/mL = ( µ g O 2 /unit in 2 mL )(units/min) 2 mL Same in each experiment at a given temp From chart: will be provided for report You may need to be able to read the chart for your exam!Sample volume Lab Report ● Lab 4 is to be submitted as a formal lab report (see the General Lab Report Guidelines AND the Lab 4 Report Requirements ) ● Your lab report must be submitted through Nexus by 11:59 PM on November 12 th as a pdf file ● It is worth 10% of your final grade! Start Now!

● Introduction : max 1000 words – Same general guidelines for information to be included.

– Why is oxygen a good measure of aerobic respiration and photosynthesis?

Why use alterations in pH? – How do our readouts relate to the biological processes we are studying? Start Now!

● Methods : no word limit – Same guidelines for preparation ● Results : no word limit – Follow the Lab 4 Report Requirements – For Part A: Data will be available to do your analysis as of Thursday midday Avoid Plagiarism!

● Ensure you are familiar with the rules and regulations on plagiarism ● You cannot utilize the same or similar phrasing as any other source! This includes the lab manual. ● All information from another source must be given in your own words and be appropriately referenced .