Experiments for the observation of protoplasmic movement
Experiments for the observation of protoplasmic movement
Within living cells, the phenomenon of active movement of protoplasm is collectively known as protoplasmic movement. Protoplasmic movement is one of the important hallmarks of living cells. Protoplasm can flow within the cell, or through the intercellular junction between the cell and the tissue, sometimes not all the protoplasm is involved in the movement but limited to the local cytoplasm, and often the surface of the protoplasm of the thylakoid layer (Hyaloplasm) is in a stationary state.
Protoplasmic movement is seen in all living cells, but is often particularly evident in certain materials. Strong protoplasmic movements are sometimes caused by mechanical damage to the material during preparation.
Operation method
Experiments for the observation of protoplasmic movement
Principle
Within living cells, the phenomenon of active movement of protoplasm is collectively known as protoplasmic movement. Protoplasmic movement is one of the important hallmarks of living cells. Protoplasm can flow within the cell or through intercellular junctions between cells and tissues. Sometimes not all protoplasm participates in the movement, but it is limited to the localized cytoplasm, and often the hyaloplasm on the surface of the protoplasm is in a quiescent state. Protoplasmic movement is seen in all living cells, but is often particularly evident in certain materials. Strong protoplasmic movement is also sometimes caused by mechanical damage to the material during preparation. Protoplasmic movement is a physiological process in which living organisms expend energy to do work, and it is closely linked to the transportation and distribution of materials in the plant as well as to a variety of enzymatic reactions. There are various forms of protoplasmic movement, generally the protoplasmic movement is categorized into two types, where the protoplasmic movement is not caused by changes in the external environment, known as spontaneous protoplasmic movement; protoplasmic movement due to some external causes is known as induced protoplasmic movement. In this experiment, we used a light microscope to observe the phenomenon of protoplasmic movement in several plant cells; we measured the speed of protoplasmic movement and observed the effect of the respiratory inhibitor 2,4-dinitrophenol (DNP) on protoplasmic movement. Move Materials and equipment For more product details, please visit Aladdin Scientific website.
Black algae, Verticillium, wheat seedlings (seed germination 2-3 days root length 1-2 cm ), purple duckweed (that is flowering), onion bulbs (ungerminated purple-skinned bulbs), epidermal hairs of pumpkin leaves or epidermal hairs of stems, protoplasmic clusters of slime molds, microscope, slides, coverslips, dissecting needles, tweezers, scissors, gauze, and microscope wipes, eyepiece micrometer, table rule, stopwatch, filter paper.
5 × 10-4 M solution of 2,4-dinitrophenol
Experimental Procedure
1. Observe the phenomenon of protoplasmic movement in several plant cells.
(1) Observation of the leaves of black algae: use tweezers to take down the young leaves of black algae and put them on the slide, add drops of water and cover the coverslip, observe under the microscope, look for the part along the middle vein of the leaf blade, and find that the chloroplasts in the cells are moving with the protoplasm along the cell wall (if the room temperature is lower than 20 ℃ or on cloudy days when you can't see the phenomenon of protoplasmic movement, you can use strong light to irradiate the cells for 15-20 minutes and then observe again). Note which parts of the whole leaf have the fastest flow of protoplasm and how the direction of flow differs between two neighboring cells.
(2) Verticillium internode cell observation, take a strain of sticky algae (containing more than two nodes) internodes, washed with water and placed on a slide, plus cover slips in the microscope to observe, due to the Verticillium internodes often have sediment outside the adhesion is not easy to see clearly, so you can first move the slide under the low-power objective, to find the appropriate part of the object and then change the high power objective to observe the cells in the arrangement of chloroplasts do not move, and the protoplasm is transparent! The chloroplasts in the cells are not moving, while the transparent part of the protoplasm is flowing together with large and small particles, carefully mobilize the fine spiral to observe carefully.
(3) Observation of wheat root hairs: Wheat roots are cut and placed on slides, cover slips are used to find the root hair area above the root tip under low magnification microscope, and then microscopically examined under high magnification microscope, transparent protoplasm can be seen to be entrapped with some particles flowing along the cell wall of the root hairs, and attention is paid to changes in the direction of the flow of the root hairs' tips and bases of the protoplasm.
(4) Observation of the stamen hairs of purple duckweed: Peel the flower of purple duckweed that is opening or about to open, remove a few stamen hairs with forceps, and observe under the microscope, and the protoplasm inside the cell can be seen to flow in an unfixed direction.
(5) Observation of the inner epidermis of an onion bulb: Tear off the inner epidermis of an onion bulb with tweezers and observe it under a microscope to see the movement of protoplasm in the cell.
(6) gently remove the epidermis of pumpkin leaves or stem epidermis, placed on a slide, drop water and cover the coverslip, under the microscope for microscopic examination, the protoplasmic filaments can be seen longitudinally and horizontally wrapped around the surface, and the movement of protoplasm can be used as an indicator of the displacement of its small particles. The direction of protoplasmic movement and its penetration into the cell through the intercellular connecting filaments were carefully observed.
(7) Observation of a germinating pollen tube shows the circulation of protoplasm through the tube.
2. Determine the speed of protoplasmic movement
Some particles of protoplasm can be used as indicators to determine the speed of protoplasm movement. However, the size of the protoplasm particles are different, its movement speed is also different, so we should try to choose the smaller particles, for multiple measurements, to find the average value.
First, the eyepiece micrometer into the eyepiece, the ruler (a small grid is equivalent to 0.1 mm or 10 μm) on the carrier stage, to find out the eyepiece micrometer each grid is equivalent to how many millimeters (or microns), remove the ruler. Place the plant material under a microscope with the same objective lens. Turn the eyepiece so that the micrometer is parallel to the direction of flow of the protoplasm, use a stopwatch to find out the time required to travel a number of frames (depending on the plant material), and take 10-20 measurements to find the average value.
3. Effect of the respiratory inhibitor DNP (2,4-dinitrophenol) on protoplasmic movement
Protoplasmic movement requires energy, which is supplied by respiration, and DNP inhibits the phosphorylation process during respiration, thus inhibiting protoplasmic movement.
The flow of protoplasm was slowed down or even stopped after 10-20 minutes when a drop of 5 x 10-4 M DNP was repeatedly added to one end of a slide and attracted to the other end by a piece of filter paper.