Chloroplastsand

Chloroplastsand is not a recognized scientific term. This article provides information on chloroplasts, the organelles responsible for photosynthesis in plants and algae. If you intended a different topic, the following overview summarizes chloroplast structure, function, and evolution.

Chloroplasts are double-mmembrane-bound organelles found in the cells of plants and algae. They carry out photosynthesis, converting light energy into chemical energy stored as glucose. In most land plants, chloroplasts are abundant in mesophyll cells of the leaf, where they optimize light capture.

Chloroplasts contain chlorophyll, the green pigment, located in internal membranes called thylakoids, which stack into grana. The fluid surrounding them is the stroma, which hosts enzymes of the Calvin cycle and a small circular DNA molecule and ribosomes.

Protein synthesis and plastid gene expression: chloroplasts retain some of their own genes; many proteins are encoded by nuclear genes and imported via transit peptides through the TOC/TIC complexes.

Biogenesis and dynamics: chloroplasts can divide and multiply within cells; they derive from endosymbiotic bacteria (cyanobacteria) and retain features of their ancestral genome.

Functions beyond photosynthesis: synthesis of fatty acids, amino acids, pigments, and starch storage inside chloroplasts.

Evolutionary significance: endosymbiotic origin is widely accepted; many lineages have plastids, and in non-photosynthetic plants or parasitic plants chloroplasts become non-photosynthetic plastids.

Interactions with the environment: light conditions influence chloroplast movement and development (etioplasts in darkness).

Chloroplast-related research continues to uncover details about gene expression and organelle biogenesis.