Experiments for the determination of the permeability of plant cytoplasmic membranes
Experiments for the determination of the permeability of plant cytoplasmic membranes
The plant cytoplasmic membrane is the interface between the cell and the external environment, and plays an important role in maintaining the cell microenvironment and normal metabolism. However, plants are often affected by external adverse factors, and the stress tolerance of different plant species is different. Determination of changes in plasma membrane permeability by the conductivity method can be used as one of the physiological indicators of plant stress tolerance. This experiment is to determine the effect of low temperature on the permeability of cytoplasmic membrane, and to master the principle and method of determining the permeability of plant cytoplasmic membrane by the conductivity meter method.
Operation method
Experiments for the determination of the permeability of plant cytoplasmic membranes
Principle
The cytoplasm of a plant cell is surrounded by a plasma membrane that has the unique function of selective permeability. All material exchanges between plant cells and the external environment must take place through the plasma membrane. The effects of various adverse environmental factors on the cells often first act on this layer of biological membranes composed of lipids and proteins. Such as extreme temperature, drought, salinity, heavy metal ions (such as Cd2 +, etc.) and atmospheric pollutants (such as SO2, HF, O3) will make the plasma membrane will be damaged to varying degrees, which is often manifested in the cell membrane permeability increases, part of the intracellular electrolyte exocytosis, the outer fluid conductivity increases. The change can be measured by a conductivity meter. The greater the permeability of the cell membrane, the more severe the damage and the weaker the resistance, and vice versa, the greater the resistance.
Materials and Instruments
Plant leaves Move 1. Cleaning appliances Conductivity Measurement Record Sheet Caveat 1. Throughout the process, the utensils contacted by the leaves must be absolutely clean (all utensils should be washed), also do not touch the leaves directly with your hands to avoid contamination. 2. the volume of the solution to be measured should be the same for each treatment and control. 3. the electrode should be cleaned after measurement. 3. The electrode should be cleaned after the measurement. Common Problems Calculate the relative extravasation rate of the electrolyte for the cryogenic and ambient treatments according to the following equation: For more product details, please visit Aladdin Scientific website.
Conductivity meter Electronic balance Refrigerator Vacuum pump Vacuum drier Constant temperature incubator Electric oven 50 ml beaker 50 ml measuring cylinder Small tweezers Gauze Petri dish Filter paper strips Lens paper Scissors Bolts Glue stick Glue tip burette Porcelain plate
All glassware used should be cleaned with washing powder first, then washed 3 times with tap water and distilled water, dried and ready for use.
2. Preparation and handling of experimental materials
The leaves of plants with similar leaf age were selected, cut and wrapped with a wet cloth. When the experiment with tap water will test leaves rinse, remove the surface dirt, and then rinse with distilled water 1 to 2 times, with a clean gauze gently absorb the surface water of the leaves, and then cut into about 1cm2 of small leaves (or with a diameter of 1 perforator drilling a small garden slice), pay attention to the removal of large leaf veins. Mix the cut small leaves well and quickly weigh three copies of the fresh sample, 1g each, into three beakers numbered A, B and C respectively. Make the following treatment:
A cup into the refrigerator below 0 ℃ for low-temperature treatment, treatment 15 ~ 30min after taking out (test leaves can also be low-temperature treatment before the experiment to be used, the temperature and time of treatment according to the different plant leaves cold tolerance), add 50 ml of distilled water.
B cup room temperature treatment, add 50 ml of distilled water.
Put A and B cups into the vacuum desiccator, pump the air with the vacuum pump for 20-30 min (to extract the air in the cell gap), then slowly put in the air and take out A and B cups from the vacuum desiccator.
Add 50 ml of distilled water to cup C, weigh it, cover the watchdish, place it on the electric stove and boil it for 10-15min (boiling time depends on different plant leaves), cool it down, weigh it again and add distilled water to the original weight, and continue to soak the leaves.
The three cups A, B and C were placed at room temperature for about 1 h (shaking frequently to favor electrolyte extravasation). The leaves were then removed from the cups for the next step of the assay.
3. Conductivity measurement
Determine the conductivity of A, B, C three cups with a conductivity meter, and at the same time determine the conductivity of distilled water (blank) (Note: After each determination of a sample solution, rinse the electrode with distilled water, and then dry the electrode with a filter paper, and then carry out the determination of the next sample solution), the measured results are recorded in the table below:
