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The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. It is not found in all cell types. It is not found in all cell types. Some cells, such as the conducting cells in xylem , possess a secondary wall containing lignin , which strengthens and waterproofs the wall.
Water can enter the cell by diffusion through the cell membrane or through selective membrane channels called aquaporins, which greatly facilitate the flow of water. [1] It occurs in a hypotonic environment, where water moves into the cell by osmosis and causes its volume to increase to the point where the volume exceeds the membrane's capacity ...
A plant cell in hypotonic solution will absorb water by endosmosis, so that the increased volume of water in the cell will increase pressure, making the protoplasm push against the cell wall, a condition known as turgor. Turgor makes plant cells push against each other in the same way and is the main line method of support in non-woody plant ...
In other words, though autolysis resembles the active process of digestion of nutrients by live cells, the dead cells are not actively digesting themselves as is often claimed, and as the synonym self-digestion suggests. Failure of respiration and subsequent failure of oxidative phosphorylation is the trigger of the autolytic process. [1]
Plasmolysis is the contraction of cells within plants due to the loss of water through osmosis. In a hypertonic environment, the cell membrane peels off the cell wall and the vacuole collapses. These cells will eventually wilt and die unless the flow of water caused by osmosis can stop the contraction of the cell membrane. [5]
Water continues to diffuse out of the cell after the point of zero turgor pressure, where internal cellular pressure is equal to the external atmospheric pressure, has been reached, generating negative pressure within the cell. [2] That negative pressure pulls the center of the cell inward until the cell wall can no longer withstand the strain. [1]
Due to osmosis, water will diffuse into the vacuole, placing pressure on the cell wall. If water loss leads to a significant decline in turgor pressure, the cell will plasmolyze . Turgor pressure exerted by vacuoles is also required for cellular elongation: as the cell wall is partially degraded by the action of expansins , the less rigid wall ...
Plant cell overview, showing secondary cell wall. The secondary cell wall has different ratios of constituents compared to the primary wall. An example of this is that secondary wall in wood contains polysaccharides called xylan, whereas the primary wall contains the polysaccharide xyloglucan. The cells fraction in secondary walls is also ...