Notes from Professor Karafit's Lecture on Cell Membrane Lab (Bio1441)

Overview of Lab

Purpose: Investigate the effect of ethanol on beetroot tonoplast membrane.
Research Question: What is the effect of ethanol on the beetroot tonoplast membrane?
Previous Lab: Standard curve based on beta-cyanin light absorption used to determine concentration of beta-cyanin leaking from beet tissue.
Bring: Standard curve from the previous lab.

Mass Balance Equation: Make sure to practice it.
Standard Curve Interpretation: Understand how to calculate beta-cyanin concentration using the equation of the line.
Pipetting: Learn to use a pipette in class.
Hypothesis Writing: Learn how to write a predictive hypothesis.

Fire Alarm:
- Bio 1 lab: Exit via stairs, meet at faculty parking lot.
- Alternative location for other classes: Yard between Lewis Science Center and Ferris Center.
Tornado Protocol: Head to the basement of Lewis Science Center.
COVID-19 Precautions: Follow designated entrance/exit protocols where applicable.

Model Organism: Beets are used because they contain beta-cyanin, which leaks when membranes are damaged.
Understanding Membranes: Helps in understanding damage mechanisms for membranes similar to human cells and viruses.

Function: Boundary between the cell's inner and outer environments; selectively permeable.
Composition: Phospholipid bilayer with:
- Hydrophilic heads (face water)
- Hydrophobic tails (oil-like)
- Embedded proteins with various functions.

Potential Damagers:
- Soap: Amphipathic; can disrupt membrane.
- Alcohol: Amphipathic; can denature proteins or dissolve membranes.
- Heat: Causes rapid molecule movement, possibly damaging the membrane.

Ethanol Dilutions: Make dilutions from 0% to 60% ethanol.
Hypothesis: Write a predictive hypothesis using the format "If... then..."
Example Hypothesis:
- If ethanol denatures membrane proteins, then membrane leakage will occur, showing resistance at low concentrations.
Data Collection:
- Set up a data collection table on page 25 of the manual.
- Use spectrophotometer at 535 nm to record absorbance.
- Record qualitative data for results section.

Prepare Beet Disks: Use cork borer to create 5mm thick disks from beets.
Rinse: Clean disks with cool water to remove beta-cyanin.
Incubate: Place disks in ethanol solutions for 5 minutes.
- May need to agitate occasionally.
Measure Absorbance: Pipette liquid into cuvette for spectrophotometer measurement.
Repetition: Run each ethanol concentration three times for accuracy.

Dress Appropriately: Closed-toed shoes and appropriate clothing; wash hands after lab.
Stay Updated: Review lab manual ahead of time to prepare for quizzes.

Take detailed notes during lab for your report.
Control Setup: Define control for ethanol tests (e.g., ethanol mixed with water).
Keep track of timing during experiments with an incubation table.
Expect a quiz covering material from previous labs and mass balance equations.