Plastids are generally considered to share a common origin with the chloroplasts of dinoflagellates, and evidence generally points to an origin from red algae rather than green.

In some algae ( such as the heterokonts and other protists such as Euglenozoa and Cercozoa ), chloroplasts seem to have evolved through a secondary event of endosymbiosis, in which a eukaryotic cell engulfed a second eukaryotic cell containing chloroplasts, forming chloroplasts with three or four membrane layers.

Chlorophyll ( also chlorophyl ) is a green pigment found in cyanobacteria and the chloroplasts of algae and plants.

In plants and algae, the galactosyldiacylglycerols, and sulfoquinovosyldiacylglycerol, which lack a phosphate group, are important components of membranes of chloroplasts and related organelles and are the most abundant lipids in photosynthetic tissues, including those of higher plants, algae and certain bacteria.

In plants and algae, photosynthesis takes place in organelles called chloroplasts.

) It is thought that the chloroplasts in plants and algae all evolved from cyanobacteria.

Heterokont chloroplasts appear to be derived from those of red algae, rather than directly from prokaryotes as occurred in plants.

* Among eukaryotes that acquired their plastids directly from bacteria ( known as Archaeplastida ), the glaucophyte algae have chloroplasts that strongly resemble cyanobacteria.

The chloroplasts in most photosynthetic dinoflagellates are bound by three membranes, suggesting they were probably derived from some ingested algae.

According to endosymbiotic theory, chloroplasts in plants and eukaryotic algae have evolved from cyanobacterial ancestors via endosymbiosis.

Euglena's chloroplasts are surrounded by three membranes, while those of plants and the green algae ( among which earlier taxonomists often placed Euglena ) have only two membranes.

This fact has been taken as morphological evidence that Euglena's chloroplasts evolved from a eukaryotic green algae.

Glaucocystophytic algae contain muroplasts, which are similar to chloroplasts except that they have a cell wall that is similar to that of prokaryotes.

Rhydophytic algae contain rhydoplasts, which are red chloroplasts that allow the algae to photosynthesise to a depth of up to 268 m.

Three evolutionary lineages have since emerged in which the plastids are named differently: chloroplasts in green algae and plants, rhodoplasts in red algae and cyanelles in the glaucophytes.

The chloroplasts, e. g., have lost all phycobilisomes, the light harvesting complexes found in cyanobacteria, red algae and glaucophytes, but instead contain stroma and grana thylakoids, structures found only in plants and in closely related green algae.

Some may contain symbiotic green algae, but there are no chloroplasts.

The glaucophytes are of interest to biologists studying the development of chloroplasts because some studies suggest that they may be similar to the original alga type that led to green plants and red algae.

The origin of the chloroplasts from green algae is supported by their pigmentation, which includes chlorophylls a and b, and by genetic similarities.

PDI has also been suggested to play a role in the formation of regulatory disulfide bonds in chloroplasts.

The Calvin cycle, Calvin – Benson-Bassham ( CBB ) cycle, reductive pentose phosphate cycle or C3 cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms.

Another redox protein, isolated from spinach chloroplasts by Tagawa and Arnon in 1962, was termed " chloroplast ferredoxin ".

Sulphur is a structural component of some amino acids and vitamins, and is essential in the manufacturing of chloroplasts.

In mitochondria, the PMF is almost entirely made up of the electrical component but in chloroplasts the PMF is made up mostly of the pH gradient.

An important component of understanding D-loop replication is that many chloroplasts and mitochondria have a single circular chromosome like bacteria instead of the linear chromosomes found in eukaryotes.

* Group III introns, a class of introns found in mRNA genes of chloroplasts in euglenoid protists.

However, this view neglects the fact that i ) both modern cyanobacteria and alpha-proteobacteria are Gram negative bacteria, which are surrounded by double membranes ; ii ) the outer membranes of the endosymbiotic organelles ( chloroplasts and mitochondria ) are very similar to those of these bacteria in their lipid and protein compositions.

Eukaryotic chloroplasts also contain a second, structurally and mechanistically unrelated, RNAP (" nucleus-encoded polymerase "; member of the " single-subunit RNAP " protein family ).

Since the start codon of the genetic code codes for the amino acid methionine, most protein sequences start with a methionine ( or, in bacteria, mitochondria and chloroplasts, the modified version N-formylmethionine, fMet ).

In its structure and functions, the cytochrome bc1 complex bears extensive analogy to the cytochrome b6f complex of chloroplasts and cyanobacteria ; cyt c1 plays an analogous role to cytochrome f, in spite of their different structures.

This insight could be translated to understand the more complex analogue of photosynthesis in cyanobacteria which is essentially the same as that in chloroplasts of higher plants.

The cytochrome b < sub > 6 </ sub > f complex ( plastoquinol — plastocyanin reductase ; ) is an enzyme found in the thylakoid membrane in chloroplasts of plants, cyanobacteria, and green algae, catalyzing the transfer of electrons from plastoquinol to plastocyanin.

Plastoquinone-plastocyanin reductase ( b6f complex ), present in cyanobacteria and the chloroplasts of plants, catalyses the oxidoreduction of plastoquinol and cytochrome f. This complex, which is functionally similar to ubiquinol-cytochrome c reductase, comprises cytochrome b6, cytochrome f and Rieske subunits.

In haploid organisms, including cells of bacteria, archaea, and in organelles including mitochondria and chloroplasts, or viruses, that similarly contain genes, the single or set of circular and / or linear chains of DNA ( or RNA for some viruses ), likewise constitute the genome.

All chloroplasts are thought to derive directly or indirectly from a single endosymbiotic event ( in the Archaeplastida ), except for Paulinella chromatophora, which has recently acquired a photosynthetic cyanobacterial endosymbiont which is not closely related to chloroplasts of other eukaryotes.

Also, cells may contain more than one type of chromosome ; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes.

These include the amount of light available, the amount of leaf area a plant has to capture light ( shading by other plants is a major limitation of photosynthesis ), rate at which carbon dioxide can be supplied to the chloroplasts to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out photosynthesis.

Other methods for elucidating the cellular location of proteins requires the use of known compartmental markers for regions such as the ER, the Golgi, lysosomes / vacuoles, mitochondria, chloroplasts, plasma membrane, etc.

* Plastids, the most notable being the chloroplasts, which contain chlorophyll a green coloured pigment which is used for absorbing sunlight and is used by a plant to make its own food in the process is known as photosynthesis.

The cells in the interior tissues of a leaf, called the mesophyll, can contain between 450, 000 and 800, 000 chloroplasts for every square millimeter of leaf.

The preprotein for chloroplasts may contain a stromal import sequence or a stromal and thylakoid targeting sequence.

Some introns appear to have significant biological function, possibly through ribozyme functionality that may regulate tRNA and rRNA activity as well as protein-coding gene expression, evident in hosts that have become dependent on such introns over long periods of time ; for example, the trnL-intron is found in all green plants and appears to have been vertically inherited for several billions of years, including more than a billion years within chloroplasts and an additional 2 – 3 billion years prior in the cyanobacterial ancestors of chloroplasts.

It was also during the Proterozoic that the first symbiotic relationships between mitochondria ( for nearly all eukaryotes ) and chloroplasts ( for plants and some protists only ) and their hosts evolved.

More detailed electron microscopic comparisons between cyanobacteria and chloroplasts ( for example studies by Hans Ris ), combined with the discovery that plastids and mitochondria contain their own DNA ( which by that stage was recognized to be the hereditary material of organisms ) led to a resurrection of the idea in the 1960s.

Cryptomonads have one or two chloroplasts, except for Chilomonas, which has leucoplasts and Goniomonas ( formerly Cyathomonas ) which lacks plastids entirely.

The hypothesis, though very well publicized, was never widely accepted by the experts, in contrast to Margulis ' arguments for the symbiotic origin of mitochondria and chloroplasts.

When there is sufficient sunlight for it to feed by phototrophy, it uses chloroplasts containing the pigments Chlorophyll a and Chlorophyll b to produce sugars by photosynthesis.

* Chloroplasts green plastids: for photosynthesis ; see also etioplasts, the predecessors of chloroplasts

The ATP synthase of mitochondria and chloroplasts is an anabolic enzyme that harnesses the energy of a transmembrane proton gradient as an energy source for adding an inorganic phosphate group to a molecule of adenosine diphosphate ( ADP ) to form a molecule of adenosine triphosphate ( ATP ).

* There is also evidence for horizontal transfer of mitochondrial genes to parasites of the Rafflesiaceae plant family from their hosts ( also plants ), from chloroplasts of a not-yet-identified plant to the mitochondria of the bean Phaseolus, and from a heterokont alga to its predator, the sea slug Elysia chlorotica.

However, chloroplasts rely more on the chemical potential of the PMF to generate the potential energy required for ATP synthesis.

At the Rockefeller Institute for Medical Research, Palade used electron microscopy to study the internal organization of such cell structures as ribosomes, mitochondria, chloroplasts, the Golgi apparatus, and others.