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In some plants such as cacti, chloroplasts are found in the stems, [186] though in most plants, chloroplasts are concentrated in the leaves. One square millimeter of leaf tissue can contain half a million chloroplasts. [11] Within a leaf, chloroplasts are mainly found in the mesophyll layers of a leaf, and the guard cells of stomata.
Chloroplasts: found in green algae (plants) and other organisms that derived their genomes from green algae. Muroplasts: also known as cyanoplasts or cyanelles, the plastids of glaucophyte algae are similar to plant chloroplasts, excepting they have a peptidoglycan cell wall that is similar to that of bacteria.
It was thought that compartmentalization is not found in prokaryotic cells., [1] but the discovery of carboxysomes and many other metabolosomes revealed that prokaryotic cells are capable of making compartmentalized structures, albeit these are in most cases not surrounded by a lipid bilayer, but of pure proteinaceous built.
The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) taken one inside the other in endosymbiosis.
Cells are broadly categorized into two types: eukaryotic cells, which possess a nucleus, and prokaryotic cells, which lack a nucleus but have a nucleoid region. Prokaryotes are single-celled organisms such as bacteria, whereas eukaryotes can be either single-celled, such as amoebae, or multicellular, such as some algae, plants, animals, and fungi.
Possible cladogram of chloroplast evolution [2] [3] Circles represent endosymbiotic events. For clarity, dinophyte tertiary endosymbioses and many nonphotosynthetic lineages have been omitted. a It is now established that Chromalveolata is paraphyletic to Rhizaria .
Chloroplast DNA (cpDNA), also known as plastid DNA (ptDNA) is the DNA located in chloroplasts, which are photosynthetic organelles located within the cells of some eukaryotic organisms. Chloroplasts, like other types of plastid , contain a genome separate from that in the cell nucleus .
In some cases, such mutations lead to cancer because they cause cells to divide more quickly and invade surrounding tissues. [49] In certain lymphocytes in the human immune system, V(D)J recombination generates different genomic sequences such that each cell produces a unique antibody or T cell receptors.