RP 4 - Investigation into the effect of a named variable on the permeability of cell-surface membranes

Method:

- Cut beetroot into 6-10 identical cubes and clean off any released pigment.

- For temperature investigation: place beetroot cubes in equal volumes of distilled water in test tubes.

- Place test tubes in a water bath at various temperatures (30-80°C).

- For solvent concentration investigation: create an ethanol dilution series (0-100% ethanol).

- Leave samples for 20 minutes for pigment leakage.

- Set the colorimeter to a blue filter and zero using distilled water in a cuvette.

- Filter each sample into cuvettes using filter paper.

- Measure absorbance for each solution, where higher absorbance indicates higher pigment concentration and membrane permeability

Risk Assessment:

-Scalpel: Cut away from fingers, use forceps, and keep away from desk edges. Treat cuts by elevating, applying pressure, and seeking medical assistance if needed.

- Broken glass: Handle glassware carefully and keep away from desk edges. Treat cuts by elevating, applying pressure, and seeking medical assistance if needed.

- Ethanol: Wear eye protection and keep away from flames. Rinse eyes and skin with cold water in case of contact.

- Hot liquids: Handle with care, use tongs, wear eye protection, and keep away from desk edges. Treat burns by running under cold water and seek medical assistance if needed.

Conclusion

-Temperature: Permeability increases with temperature as heat denatures membrane proteins, creating gaps in the membrane, facilitating molecule passage. Low temperatures make membranes rigid, reducing permeability, though very low temperatures can lead to ice crystal formation, increasing permeability.

- Ethanol concentration: Higher concentrations of ethanol cause membrane rupture, releasing betalain pigment. More ethanol disrupts the membrane, increasing gaps and permeability

nd

r