What are Organelles and What are Their Functions?
In this article, we are going to discuss the Organelles meaning.
Organelles can be defined as small structures within the cytoplasm that carry out functions necessary to maintain homeostasis in the cell.
Organelles are involved in many processes, for example, energy production, building proteins, secretions, destroying toxins, and are also involved in responding to external signals.
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Two Categories of Organelles
Organelles are considered either membranous or nonmembranous.
Membranous Organelles possess their own plasma membrane which is used to create a lumen separate from the cytoplasm.
Organelles may be the location of hormone synthesis or they may be the location of degradation of macromolecules.
Non-membranous Organelles are not surrounded by a plasma membrane and most non-membranous Organelles are part of the cytoskeleton, which is the major support structure of the cell.
These include filaments, microtubules, and centrioles.
Examples of Organelles
In eukaryotic organisms, nearly every cell has a nucleus though there are exceptions. The other common Organelles seen are listed below-
Mitochondria
Plastids (among autotrophs)
Endoplasmic reticula
Golgi apparatus
Lysosomes
Vacuoles.
Some special cells or Organelles like neurons also contain synaptic vesicles. All of these structures are membrane-bound. Macromolecular complexes like ribosomes, spliceosomes, centrioles, as well as centrosomes are not surrounded by a membrane, but are important Organelles in most cells, performing vital functions like organizing the cytoskeleton, synthesizing proteins, and processing RNA.
Functions of Organelle
Nutrition - The function of the unicellular organisms ingest food as large particles from the environment and then undergo intracellular digestion. This process needs the presence of Organelles such as food vacuoles or it needs the presence of phagosomes and lysosomes which carry digestive enzymes.
Transport - Intracellular transport is often managed through crisscrossing cytoskeletal filaments and these act like corridors. These filaments form a series of pathways that position Organelles as well these filaments transport materials. In this activity, filaments are aided by motor proteins that usually contain two domains – one which is used to interact with the cargo and the other to navigate the cytoskeletal filament.
Cell Organelles Meaning
Let’s know what is meant by cell Organelles! The cellular components are known as Cell Organelles. These cell Organelles include both membrane-bound Organelles and non-membrane-bound Organelles, present within the cells and are distinct in their structures and functions. These cell Organelles are responsible to coordinate and function efficiently for the normal functioning of the cell. A few of them function by providing shape as well as support, whereas some are involved in the locomotion and reproduction of a cell. There are various Organelles that are present within the cell. They are classified into three categories based on the presence or absence of a membrane.
Organelles Without Membrane: Cell wall, Ribosomes, Cytoskeleton
Single membrane-bound Organelles: Vacuole, Lysosome, Golgi Apparatus, Endoplasmic Reticulum are some single membrane-bound Organelles.
Double Membrane-Bound Organelles: Nucleus, mitochondria and chloroplast.
The difference between Organs and Organelles
Organ, as well as Organelle, are two structural units, which are specialized to perform a unique function in the body of animals.
The Main Difference between an Organ and an Organelle is That -
An organ is a large part of an organism, composed of tissues that perform similar functions.
An Organelle is a specialized structure found inside cells that carry out a specific life process.
Organelles from cells.
Cells form tissues, and tissues form organs. Organelles occur in all eukaryotes. They are microscopic.
But, organs are macroscopic and can only be found in animals and plants. Here are some Organelles -Mitochondria, chloroplast, Golgi apparatus, endoplasmic reticulum, and the nucleus.
The kidney, heart, liver, lungs, and brain are the organs in humans. Flowers, seeds, as well as spores, are the reproductive organs in angiosperms.
Different Cell Organelles and Their Functions
More about Organelles
Organelles are the cellular subunits. There are a slew of them, each with its unique purpose. These are given as follows:
Plasma Membrane
It is a cellular Organelle that surrounds and protects the contents of the cell. In addition to enclosing cell contents, the plasma membrane regulates the movement of substances into and out of the cell.
As a result, it participates actively in both passive and active transport to and from the cell. These activities also aid in the maintenance of balance even when external conditions change.
Two layers of phospholipids make up the plasma membrane (phospholipids bilayer).
Nucleus/DNA
The chromatic nucleoplasm/nuclear sap, and nucleolus are some of the primary components of the nucleus.
DNA (hereditary material), as well as different proteins and the nucleolus, are all housed in the nucleus.
The center of the eukaryotic cell is enclosed by a nuclear membrane. It is the Organelle that directs behaviors such as protein synthesis and cell division, among others, to govern an organism's genetic traits.
The DNA of prokaryotes does not have a nuclear membrane. As a result, the genetic material is bonded in the nucleotide region.
The nuclear membrane is important in ribosome production.
Ribosome
Ribosomes are small organelles found in the cytoplasm that carry RNA and particular proteins. Ribosomes engage directly in the creation of proteins within the cell by using their RNA and amino acids.
This procedure entails decoding the information contained in the RNA and producing the needed proteins utilizing amino acids.
Mitochondria
Mitochondria are the biggest Organelles in the cell. Mitochondria, unlike some other Organelles, contain DNA, allowing them to function independently. Mitochondria feature a double-membrane structure with cristae on the inner membrane.
In the presence of oxygen, mitochondria, also known as the powerhouse, are involved in respiration and create ATP (adenosine triphosphate) from substrates. Mitochondria can use their DNA to encode some of the components they need to do their activities.
Vacuoles
A vacuole is a cell compartment that has no cytoplasm and is empty. It holds fluid and is encased in a membrane. Vacuoles are engaged in the export of waste from the cell in circumstances where the cell's waste products are present, therefore protecting the cell from toxicity.
Cytoskeleton
Microtubules and microfilaments make up the cytoskeleton. The cytoskeleton helps preserve the form of the cell while also ensuring its flexibility by spreading throughout the cell (in the cytoplasm).
Plastids
Plant cells and algae contain plastids, which are a type of Organelle. Plastids, like mitochondria, are membrane-bound Organelles that house nucleoids. They are hence semi-autonomous organ cells.
Chloroplasts, chromoplasts, protoplasts, and leucoplasts are some of the different forms of plastids.
Endoplasmic Reticulum (ER)
The endoplasmic reticulum (ER) is a flattened sac Organelle found in eukaryotic cells that creates an interconnected network (cisternae). The ER, like many other Organelles found in eukaryotes, is surrounded by a membrane. The ER is split into two sections, each with its structure and function.
Centriole
Most eukaryotic cells contain centrioles, which are cylindrical Organelles. They contain microtubules, which are tube-shaped molecules that assist the splitting and moving of chromosomes during cell division.
Lysosome
A collection of enzyme-filled sacs is referred to as a "lysosome." They're acidic enzymes (hydrolase enzymes) that assist the cell to break down macromolecules like lipids and nucleic acids.
Acidic conditions have been discovered inside lysosomes. The lysosome membrane maintains these conditions, allowing the enzymes to perform their jobs in a suitable environment. Acidocalcisomes are lysosome-related Organelles found in eukaryotes.
Golgi Apparatus
In humans, the Golgi apparatus is extensively folded into cisternae (flattened sacs). They're protected by a membrane that varies in thickness depending on their location. The Golgi apparatus in the cell is involved in the production, storage, and transit of ER products.
FAQs on Organelle
1. What exactly is a cell organelle?
Think of a cell as a tiny, bustling city. An organelle is like a specific building or service in that city, such as a power plant or a control centre. It is a specialized, membrane-bound structure within a cell that performs a specific job, essential for keeping the cell alive and functioning properly.
2. What are the main organelles found in a typical animal cell?
A typical animal cell contains several key organelles, each with a unique role. The most common ones include:
- The Nucleus, which contains the cell's genetic material (DNA).
- Mitochondria, the powerhouses that generate energy for the cell.
- Ribosomes, responsible for building proteins.
- The Endoplasmic Reticulum (ER), which helps synthesise and transport proteins and lipids.
- The Golgi apparatus, which modifies, sorts, and packages materials for transport.
- Lysosomes, which act as the cell's recycling centres by breaking down waste.
3. Why are they called 'organelles'?
The term 'organelle' means "little organ." This name was chosen because these structures function within a cell much like organs function within a body. Just as the heart, lungs, and stomach perform specific jobs to keep a person alive, organelles like the nucleus and mitochondria perform vital jobs to keep the cell alive.
4. What are the key differences between the organelles in a plant cell and an animal cell?
While both cell types share many organelles, plant cells have three distinct structures that animal cells lack. These are:
- The cell wall, a rigid outer layer that provides structural support.
- Chloroplasts, the site of photosynthesis where sunlight is converted into food.
- A large central vacuole, which stores water and maintains pressure inside the cell.
5. Why is the nucleus often called the 'brain' of the cell?
The nucleus is referred to as the 'brain' or 'control center' because it contains the cell's DNA. This DNA holds all the instructions for the cell's activities, including growth, metabolism, and reproduction. By controlling which instructions are used and when, the nucleus effectively directs and manages everything that happens inside the cell.
6. If an organelle stops working, what happens to the cell?
If a crucial organelle fails, the cell's health is immediately at risk, much like a power plant failure affects a city. For example, if the mitochondria stop working, the cell would lose its main energy supply and would not be able to perform its functions, likely leading to cell death. The specific outcome depends on which organelle fails and its importance to the cell's survival.
7. Are the cell wall and cytoplasm considered organelles?
This is a common point of confusion. Generally, an organelle is a membrane-bound structure inside the cell. The cytoplasm is the jelly-like substance that fills the cell and in which the organelles are suspended, so it is not considered an organelle itself. The cell wall, found in plant cells, is a protective layer outside the cell membrane and is also not classified as an organelle, but as a vital structural component.
8. How does understanding organelles help in our daily lives?
Understanding organelles is key to understanding health and disease. Many diseases, like certain mitochondrial disorders, are caused by malfunctioning organelles. Knowing how organelles work helps scientists develop treatments and understand processes like aging, how our bodies fight infections, and how we get energy from food.
