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Sieve cells are long, conducting cells in the phloem that do not form sieve tubes. The major difference between sieve cells and sieve tube members is the lack of sieve plates in sieve cells. [1] They have a very narrow diameter and tend to be longer in length than sieve tube elements as they are generally associated with albuminous cells. [4]
As a result, the concentration of sucrose increases in the sieve tube elements. This causes water to move into the sieve tube element by osmosis, creating pressure that pushes the sap down the tube. In sugar sinks, cells actively transport sucrose out of the sieve tube elements, first to the apoplast and then to the symplast of the sink.
These porous connections are called sieve plates. In spite of the fact that their cytoplasm is actively involved in the conduction of food materials, sieve-tube members do not have nuclei at maturity. It is the companion cells that are nestled between sieve-tube members that function in some manner bringing about the conduction of food.
A molecular sieve is a material with pores (voids or holes), having uniform size comparable to that of individual molecules, linking the interior of the solid to its exterior. These materials embody the molecular sieve effect , the preferential sieving of molecules larger than the pores.
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Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
The main mechanism for closing damaged sieve elements involves P-proteins, which act as a plug in the sieve element pores. P-proteins essentially plug the pores that form in sieve elements. [2] They act as a stopper in the damaged sieve elements by blocking the open channels so that no additional sap or sugar can be lost. [2]
Metal laboratory sieves An ami shakushi, a Japanese ladle or scoop that may be used to remove small drops of batter during the frying of tempura ancient sieve. A sieve, fine mesh strainer, or sift is a tool used for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet ...