What makes up chloroplasts

Chloroplasts are divided by a huge protein complex, also called the plastid-dividing PD machinery, and their division is also regulated by many factors to get an optimized number and size of chloroplasts in the cell. These processes are fundamental for the biogenesis and three-dimensional dynamic structure of chloroplasts. During the photosynthesis, reactive oxygen species ROS and other cellular signals can be made.

As an important metabolic hub of the plant cell, the chloroplast health has been found critical for a variety of abiotic and biotic stresses, including drought, high light, cold, heat, oxidative stresses, phosphate deprivation, and programmed cell death at sites of infection.

Therefore, a better understanding the responses of chloroplasts to these stresses is part of knowing how the plant itself responds.

Ultimately, this knowledge will be necessary to engineer crops more resistant to common stresses. With the current global environment changes, world population growth, and the pivotal role of chloroplasts in carbon metabolism, it is of great significance to represent the advancement in this field, for science and society. Tremendous progresses have been made in the field of chloroplast biology in recent years. Through concerted efforts from the community, greater discoveries definitely will emerge in the future.

This Research Topic welcomes all types of articles. It contains enzymes, molecules, and ions. It is where the light-independent process of sugar formation takes place the dark reactions of photosynthesis. Similar to the mitochondria , the chloroplasts are semi-autonomous organelles. Thus, they do not solely rely on the genes contained in the nucleus. They produce certain proteins from their own DNA. What is the function of the chloroplast? Chloroplasts carry out the process of photosynthesis.

Their main role is to provide the site for light and dark reactions. Through these organelles, inorganic sources, water, and light energy are converted into food, i. They are, therefore, important to photosynthetic organisms for the purpose of producing food on their own and not needing to feed on other organisms to survive. Because oxygen is one of the byproducts of photosynthesis, the chloroplasts are therefore a crucial site for producing such gas, which later is released from the cell into the environment.

Oxygen is biologically important for its role, in turn, in various biochemical and physiological processes in animals. For further description and facts on photosynthesis, read Plant Metabolism tutorial.

The Endosymbiotic theory was conceptualized to delineate the origin of chloroplasts. The eukaryotic cell, being the larger cell, took in the smaller photosynthetic prokaryotes e. Eventually, the prokaryotes evolved and differentiated into plastids, particularly, chloroplasts.

These early photosynthetic eukaryotes harboring prokaryotes-turned-organelles are presumed to be the early ancestors of modern plants and algae on Earth. The discovery of the cpDNA in chloroplasts, the similarity in membranes, and the binary fission as a means of reproduction serve as evidence that supports this theory. Read also: What is the Likely Origin of Chloroplasts?

Plants are responsible for incredible feats of molecular transformation. Plant processes, such as photosynthesis, photophosphorylation, chemiosmosis, carbon fixing reactions, respiration, are presented in this tutorial Read More. Plant cells have plastids essential in photosynthesis.

They also have an additional layer called cell wall on their cell exterior. Although animal cells lack these cell structures, both of them have nucleus, mitochondria, endoplasmic reticulum, etc. Read this tutorial to learn plant cell structures and their roles in plants Photosynthesis is the process that plants undertake to create organic materials from carbon dioxide and water, with the help of sunlight- all of which are investigated in this tutorial Leaves are the major photosynthetic organ of a plant.

The ellipsoid-shaped chloroplast is enclosed in a double membrane and the area between the two layers that make up the membrane is called the intermembrane space. The outer layer of the double membrane is much more permeable than the inner layer, which features a number of embedded membrane transport proteins. Enclosed by the chloroplast membrane is the stroma , a semi-fluid material that contains dissolved enzymes and comprises most of the chloroplast's volume. In higher plants, lamellae , internal membranes with stacks each termed a granum of closed hollow disks called thylakoids , are also usually dispersed throughout the stroma.

The numerous thylakoids in each stack are thought to be connected via their lumens internal spaces. Light travels as packets of energy called photons and is absorbed in this form by light-absorbing chlorophyll molecules embedded in the thylakoid disks. When these chlorophyll molecules absorb the photons, they emit electrons, which they obtain from water a process that results in the release of oxygen as a byproduct.

The movement of the electrons causes hydrogen ions to be propelled across the membrane surrounding the thylakoid stack, which consequently initiates the formation of an electrochemical gradient that drives the stroma's production of adenosine triphosphate ATP. ATP is the chemical energy "currency" of the cell that powers the cell's metabolic activities.

In the stroma, the light-independent reactions of photosynthesis, which involve carbon fixation, occur, and low-energy carbon dioxide is transformed into a high-energy compound like glucose. Plant cells are remarkable in that they have two organelles specialized for energy production: chloroplasts, which create energy via photosynthesis, and mitochondria, which generate energy through respiration, a particularly important process when light is unavailable.

Like the mitochondrion, the chloroplast is different from most other organelles because it has its own DNA and reproduces independently of the cell in which it is found; an apparent case of endosymbiosis. Scientists hypothesize that millions of years ago small, free-living prokaryotes were engulfed, but not consumed, by larger prokaryotes, perhaps because they were able to resist the digestive enzymes of the engulfing organism. According to DNA evidence, the eukaryotic organisms that later became plants likely added the photosynthetic pathway in this way, by acquiring a photosynthetic bacterium as an endosymbiont.

As suggested by this hypothesis, the two organisms developed a symbiotic relationship over time, the larger organism providing the smaller with ample nutrients and the smaller organism providing ATP molecules to the larger one. Eventually, the larger organism developed into the eukaryotic cell, the smaller organism into the chloroplast.