Organelle is a specialized subunit within a cell. It performs specific function. Cells are surrounded by a plasma membrane, which is made of a bilayer of phospholipids. Organelles are identified by microscope.
Cell Organelle and their functions are as:
1. Nucleolus:
The prominent structure in the nucleus is the nucleolus also called nucleole. This is a non-membrane bound structure. The nucleolus produces ribosomes, which move out of the nucleus and take positions on the rough endoplasmic reticulum where they are critical in protein synthesis.
2. Nucleus:
The nucleus is the most importent membrane-enclosed organelle in eukaryotic cells. It communicates with the surrounding cytosol via numerous nuclear pores. It contains most of the cell’s genetic material, organized as multiple long linear DNA responsible for providing the cell with its unique characteristics. The DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or off - that’s why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell. When a cell is dividing, the DNA and surrounding protein condenses into chromosomes that are easily seen by microscopy.
3. Ribosomes:
Ribosomes are packets of RNA and protein that found in a cell and play a crucial role in both prokaryotic and eukaryotic cells. Protein synthesis occur here.
The ribosome functions in the expression of the genetic code from nucleic acid into protein, in a process called translation. Each ribosome comprises two parts, 65% ribosomal RNA and 35% ribosomal proteins. Messenger RNA from the cell nucleus is moved systematically along the ribosome where transfer RNA adds individual amino acid molecules to the lengthening protein chain.
4. Vesicle:
Also called Secretory Vesicle. Vesicle is a relatively small, intracellular, membrane-enclosed sac that stores or transports substances. Cell secretions - e.g. hormones, neurotransmitters - are packaged in secretory vesicles at the Golgi apparatus. The secretory vesicles are then transported to the cell surface for release. The vesicle is separated from the cytosol by at least one lipid bilayer.
If there is only one lipid bilayer, they are called unilamellar vesicles; otherwise they are called multilamellar.
5. Vacuoles:
Vacuole is a single layer of unit membrane-bound sac enclosing fluid in it. Act as storage house found in cells. Plays important role in intracellular digestion and the release of cellular waste products. In animal cells, vacuoles are generally small.
In plant cells Vacuoles are large and play a role in turgor pressure. When a plant is well-watered, water collects in cell vacuoles producing rigidity in the plant. Without sufficient water, pressure in the vacuole is reduced and the plant wilts.
Functions:
- produces turgor pressure against cell wall for support
- stores water and various chemicals may store insoluble wastes
- Remove unwanted structural debris
- Containing waste products and isolating materials that might be harmful or a threat to the cell
- Maintain internal hydrostatic pressure or turgor within the cell
- Maintain an acidic internal pH
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