Organelle

Cells have tiny parts inside.

These parts do special jobs. They work like little organs. Some parts have a thin skin around them. This skin keeps the part safe. Other parts do not have a skin.

One part is the center. It tells the cell what to do. Another part makes energy. It helps the cell work. Plants have a part to catch sunlight too.

Some parts move the cell. Others store things. These tiny parts are very important. They help the cell stay alive.

Cells are made of many tiny parts. We call these parts organelles.

The name comes from the word "organ." Just as organs help your body work, organelles help a cell work. Some organelles have a thin skin around them. This skin is called a membrane. Other organelles do not have a skin. They are made of large groups of proteins.

There are many different types. The nucleus is a big part. It holds DNA and controls the cell. Mitochondria make power for the cell. Plants and algae have chloroplasts. These parts trap power from sunlight.

Some cells are very simple. These are called prokaryotes. They do not have many parts. But some do have tiny shells. These shells hold special parts inside. Scientists use microscopes to see them. They can also use a way called cell fractionation to study them. This helps us learn how life works.

An organelle is a tiny part inside a biological cell. Each organelle has a specific job to do. The name comes from the word "organ." Just as your heart or lungs are organs in your body, organelles are the small parts that make a cell work.

Some organelles are wrapped in a thin skin called a lipid bilayer. These are called membrane-bound organelles. Other organelles do not have a skin. These are called membrane-less organelles. They are often made of large groups of proteins.

Organelles work in many different ways. Some parts help move things around or store materials. For example, the nucleus holds DNA and controls all cell activities. Mitochondria make energy by using glucose. This process helps the cell stay alive.

Plants and algae have even more parts. They use chloroplasts to trap energy from sunlight. This is called photosynthesis. Other parts, like the Golgi apparatus, sort and package proteins. The endoplasmic reticulum helps fold new proteins. Each step happens in a specific order to keep the cell running.

Scientists have studied these tiny parts for a long time. In the 1830s, Félix Dujardin studied microorganisms. He showed they were different from larger animals. Later, a German zoologist named Karl August Möbius used the term "organella." He wrote this in 1884. He used the word to mean "little organ." This helped explain that these parts are just different parts of one cell.

There are many different kinds of organelles. In eukaryotic cells, you can find the nucleus and vacuoles. The nucleus is a double-membrane compartment. Vacuoles are single-membrane parts used for storage.

Some cells have many mitochondria to make power. Other cells, like those in plants, have plastids. In bacteria, things are a bit different. Some bacteria have carboxysomes. These are tiny shells that are 100 to 200 nanometers wide.

Other bacteria, like Planctomycetota, have special internal membranes.

Learning about organelles helps us understand all living things. Even simple cells, called prokaryotes, have special structures. Some bacteria have magnetosomes to help them move. Others have structures like the flagellum to help them swim.

We can see these parts using a microscope. Scientists also use a method called cell fractionation to study them. This lets them pull different parts away to look closely. By studying these tiny pieces, we learn how life works from the inside out.

An organelle is a specialized subunit found within a biological cell. Each organelle performs a specific function to help the cell operate. The term comes from the word "organ," which refers to a functional unit in a body. The suffix "-elle" is a diminutive, meaning "little organ."

Organelles are essential because they allow a cell to organize different tasks into separate areas. This organization helps life function efficiently at a microscopic level.

Organelles are categorized by how they are structured. Many are membrane-bound organelles. These are enclosed within their own lipid bilayers, which are thin layers of fats. Other structures are non-membrane-bound organelles, also called membrane-less organelles (MLOs). These are large assemblies of macromolecules, such as proteins, that carry out specialized tasks. Some MLOs are referred to as proteinaceous organelles because proteins form their main structure.

The formation of these membrane-less structures is sometimes compared to liquid-liquid phase separation.

In eukaryotic cells, organelles form complex systems. The endomembrane system includes parts like the nuclear envelope, the endoplasmic reticulum, and the Golgi apparatus. The nucleus is a double-membrane compartment that maintains DNA and controls cell activities. The endoplasmic reticulum helps with the translation and folding of new proteins. The Golgi apparatus then sorts, packages, and modifies these proteins.

Other major organelles include mitochondria, which produce energy from glucose, and vacuoles, which handle storage and transportation.

Plants, algae, and some protists possess additional types of organelles called plastids. A common example is the chloroplast, which is a double-membrane compartment. Chloroplasts perform photosynthesis by trapping energy from sunlight. Mitochondria and plastids are unique because they are considered endosymbiotic. This means they were likely engulfed by an ancestral cell long ago.

The number of these organelles can change depending on what the specific cell needs to do.

Historically, the study of these structures has evolved significantly. In the 1830s, Félix Dujardin refuted a theory by Ehrenberg. Ehrenberg believed microorganisms had the same organs as multicellular animals, just smaller. In 1884, German zoologist Karl August Möbius is credited with first using the term "organella." He used this diminutive of "organ" to explain that these were parts of a single cell. This helped scientists distinguish between cellular structures and the organs of complex animals.

While eukaryotes are highly complex, prokaryotes also have specialized structures. For a long time, it was thought that prokaryotes lacked internal organization. However, research shows that some bacteria contain protein-shelled microcompartments called carboxysomes. These are very small, measuring only 100 to 200 nanometers in diameter.

Other bacteria, such as those in the phylum Planctomycetota, have internal membranes. Some even have anammoxosomes for specific chemical processes.

Scientists identify and study these structures using various tools. Microscopy allows researchers to see larger organelles, like the nucleus, under a light microscope. For smaller details, more advanced methods are required. Cell fractionation is a process used to purify specific organelles for study. This allows scientists to separate the different parts of a cell to examine them individually. Understanding these components connects us to the broader study of how all living systems are organized.