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Enzymes: Form and Function
Catalytic proteins
Lower activation energy of reaction
Combine or break apart substrates
Not used up in reaction
End in –ase
Lactase metabolizes lactose
DNA Polymerase – polymerize nucleotides
Substrate to product
1
Energy of activation with enzyme
Energy needed to run reaction without an enzyme
Temp & pH
Changes in environmental conditions will alter enzyme structure, and therefore alter its function
Enzyme activity measured by
Initial reaction velocity (IRV)
Amount of product per time
this is what you’re doing in today’s experiment
Or could use amount of product per degree (for a temperature graph)
what is shown in the graph above
IRV = (slope of the graph)
Reaction you will run:
the reaction goes from clear to brown
peroxidase is not used up in reaction
guaiacol gets oxidized; hydrogen peroxide gets reduced
This is a redox reaction; Think about how rust turns a different color when iron is oxidized
Baseline: Filtered water – are the enzyme concentrations too weak/strong?
Question: how does pH impact the function of peroxidase?
Hypothesis: _______________________________________
Experiment: try at pH of 4, 7, and 10
guaiacol (clear) + H2O2 tetraguaiacol (brown) + H20
peroxidase
Experiment
USE CORRECT PIPETTE FOR EACH CHEMICAL
Make sure to only take out 300 microliters of Guaiacol
100 microliters to .1 milliliter
Get Guaiacol from me
Prepare your blank to tare the colorimeter – fill cuvette 2/3 full and make sure the clear side of cuvette is perpendicular to the colorimeter’s light
Don’t touch the clear sides (fingerprints are a problem).
Micropipettes:
Don’t turn upside down. 1st resistance to extract chemical; 2nd resistance to eject chemical. Pay attention to units on pipette. Don’t reuse tips.
Before adding enzyme solution to test, have all of your supplies ready:
your colorimeter tared and ready to go
Guaiacol, pH buffer, and H202 in a test tube
stopwatch
Once enzyme is added, quickly pour into cuvette and place in colorimeter, recording every 15 sec.
Input data into excel sheet for all of class to record
Calculate IRV using greatest difference between two adjacent points
You will make a line graph of our data using Excel (there will be 4 lines on graph)
BRING THIS GRAPH NEXT WEEK TO CHECK CORRECTNESS!
We will cover components of the lab report following your lab practical next week
You will have access to sample lab reports, rubrics, instructions
Topic: Effects of pH on Peroxidase
upcoming due dates:
Materials and Methods – due March 15th 11:59pm on Canvas
Literature Review – due April 1st 11:59pm on Canvas
Introduction – due April 8th 11:59pm on Canvas
entire lab report – due April 22nd 11:59pm on Canvas
Lab Report – due March 25th 11:59pm on Canvas using Turnitin
Next week: BSC110L LAB PRACTICAL
covers labs: Topics 1-4 (scientific method, biomolecules, microscopes and cells,
enzymes)
worth 20% of your grade!
DO NOT arrive late
no electronics on your person (phones, ear buds, smartwatches in your bag)
Written Exam: 40-45 questions on written portion
55 questions, 2 points each
One or two stations for practical applications: I will be monitoring you at these stations and giving you points upon satisfactory completion (10-15 points)
when complete: students can either turn their paper in or revisit stations one
at a time for a short period
Revisit the powerpoints for all of the labs
Review the lab manual pages
If we thought it was important enough to put in a powerpoint or cover it in a quiz or do it as an activity, it’s important enough to put on the exam!
Use the study guide found on Canvas
Biology Tutoring (Walker Science room 149)
Tutoring for BSC 110/111:
Monday 8am – 7pm
Tuesday 8am – 11am and 2:30pm – 5pm
Wednesday 8am – 5pm
Thursday 8am – 11am and 2:30pm – 3:30pm
Friday 9am – 10:30am
Tutoring for BSC 107/250/251:
Monday 10am – 12pm
Wednesday 10am – 12pm
Thursday 5:30pm – 7pm
Friday 8am – 12pm
A graduate student will be present who can help with lab reports during the following times:
Tuesday 10am – 12pm and 2pm – 5pm
Wednesday 10am – 12pm and 2pm – 5pm
Thursday 10am – 12pm and 2pm – 5pm
Friday 10am – 12pm
From the syllabus: Students arriving more than 15 minutes late for a lab practical will not be allowed to take the practical during the allotted time. If a suitable excuse is provided to the teaching assistant and approved by the lab coordinator, a make-up lab practical may be scheduled.
In the event a student misses a lab practical due to family emergency, illness, or University function, contact the Teaching Assistant and Lab Coordinator immediately. If the student does not contact the Teaching Assistant and Lab Coordinator within 48 hours of the exam, the student will not be allowed to make up the missed assessment.
In addition, a verified excuse must be obtained from the Assistant to the Vice President of Student Affairs in Union 219 and submitted to the Teaching Assistant and Lab Coordinator within one week of the date of the exam. After review and approval of the excuse, the Teaching Assistant and Lab Coordinator will work with the student to arrange a date and time for a make-up practical. A student is only allowed to make up one lab practical during the semester. If there was no prior contact and/or verified excuse obtained, as explained above, the student will receive a score of zero on any assessment for that day.
Today:
Activities: Enzymes Lab
Prepare for the week of the 7th:
Study!
Prepare for the week of the 21st:
Fill out Excel sheet with your data
Study for quiz on topics 4 and 5
Prelab for Topic 5: Visualizing Metabolism: Respiration and Photosynthesis
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