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Each of the envelope membranes is a lipid bilayer that is between 6 and 8 nm thick. The lipid composition of the outer membrane has been found to be 48% phospholipids, 46% galactolipids and 7% sulfolipids, while the inner membrane has been found to contain 16% phospholipids, 79% galactolipids and 5% sulfolipids in spinach chloroplasts.
A chloroplast (/ ˈklɔːrəˌplæst, - plɑːst /) 1 2 is a type of organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. Chloroplasts have a high concentration of chlorophyll pigments which capture the energy from sunlight and convert it to chemical energy and release oxygen.
Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: granum).
The endomembrane system is composed of the different membranes (endomembranes) that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles. In eukaryotes the organelles of the endomembrane system include: the nuclear membrane, the endoplasmic reticulum ...
The cell envelope comprises a plasma membrane, seen here in light brown, and a thick peptidoglycan-containing cell wall (the purple layer). No outer lipid membrane is present, as would be the case in gram-negative bacteria. The red layer, known as the capsule, is distinct from the cell envelope.
Chloroplast. Stroma, in botany, refers to the colorless fluid surrounding the grana within the chloroplast. [1] Within the stroma are grana (stacks of thylakoid), the sub-organelles where photosynthesis is started [2] before the chemical changes are completed in the stroma. [3]
Cellular compartments in cell biology comprise all of the closed parts within the cytosol of a eukaryotic cell, usually surrounded by a single or double lipid layer membrane. These compartments are often, but not always, defined as membrane-bound organelles. The formation of cellular compartments is called compartmentalization.
For example, the mitochondrial matrix separates the mitochondrion into many compartments. In the eukaryotic cell, the cytosol is surrounded by the cell membrane and is part of the cytoplasm, which also comprises the mitochondria, plastids, and other organelles (but not their internal fluids and structures); the cell nucleus is separate. The ...