![Plant cells contain membrane-bound organelles, including fluid-filled spaces, called vacuoles, that …[Credits : Encyclopædia Britannica, Inc.]](http://media-2.web.britannica.com/eb-media/89/91689-003-0A33884E.gif)
Most plant cells contain one or more membrane-bound vesicles called vacuoles. Within the vacuole is the cell sap, a water solution of salts and sugars kept at high concentration by the active transport of ions through permeases in the vacuole membrane. Proton pumps also maintain high concentrations of protons in the vacuole interior. These high concentrations cause the entry, via osmosis, of water into the vacuole, which in turn expands the vacuole and generates a hydrostatic pressure, called turgor, that presses the cell membrane against the cell wall. Turgor is the cause of rigidity in living plant tissue.
In the mature plant cell, as much as 90 percent of cell volume may be taken up by a single vacuole; immature cells typically contain several smaller vacuoles.
Principal-structures-of-an-animal-cell-Cytoplasm-surrounds-the-cellsPrincipal structures of an animal cell[Credits : © Merriam-Webster Inc.]
Animal-cells-and-plant-cells-contain-membrane-bound-organelles-includingAnimal cells and plant cells contain membrane-bound organelles, including a distinct nucleus. In …[Credits : Encyclopædia Britannica, Inc.]
Cutaway-drawing-of-a-eukaryotic-cellCutaway drawing of a eukaryotic cell.[Credits : Encyclopædia Britannica, Inc.]
The-eight-step-tricarboxylic-acid-cycleThe eight-step tricarboxylic acid cycle.[Credits : Encyclopædia Britannica, Inc.]
The-initial-proposal-of-the-structure-of-DNA-by-JamesThe initial proposal of the structure of DNA by James Watson and Francis Crick was accompanied by a …[Credits : Encyclopædia Britannica, Inc.]
Molecular-genetics-emerged-from-the-realization-that-DNA-and-RNAMolecular genetics emerged from the realization that DNA and RNA constitute the genetic material of …
The-ovum-contains-a-small-collection-of-cells-in-theThe ovum contains a small collection of cells in the early stages of human development. As cells …[Credits : Encyclopædia Britannica, Inc.]
A-molecular-view-of-the-cell-membrane-Intrinsic-proteins-penetrateA molecular view of the cell membrane[Credits : Encyclopædia Britannica, Inc.]
Cells are the basic units of life.[Credits : Encyclopædia Britannica, Inc.]
Cells ingest molecules through their plasma membranes.[Credits : Encyclopædia Britannica, Inc.]
The carbon atom is essential to all organic compounds. Every carbon atom can bond with four other …[Credits : Acquired from Vast Video]
Most enzymes are proteins. Enzymes regulate nearly all chemical reactions that occur in living …[Credits : Acquired from Vast Video]
The location, importance, and mechanisms of photosynthesis.[Credits : Encyclopædia Britannica, Inc.]
ATP is the key source of energy in the cells of the body. The water-mediated reaction known as …[Credits : Acquired from Vast Video]
James Watson and Francis Crick revolutionized the study of genetics when they discovered the …[Credits : Acquired from Vast Video]
The structure and movement of cilia and flagella.[Credits : Encyclopædia Britannica, Inc.]
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