The cell is the most basic unit of life, and it consists of various parts called organelles which are specialized sub-units each having their own specific functions. In eukaryotic cells, each organelle is separately enclosed in their own lipid bilayers. This feature of enclosed organelles is not found in prokaryotic cells.
The following are the organelles of a cell (indicated if present in mammals or plants):
- Cell Wall [plants only] - rigid outer layer of a plant cell made up of cellulose whose function is to support and protect the cell and its contents.
- Cell Membrane - in plants, this is located inside the cell wall; while in animals, it consists of a lipid bilayer. The main function of a cell membrane is to control what comes in and out of the cell (it is semi-permeable).
- Nucleus - the nucleus contains the genetic material, the DNA. This is where transcription of the DNA happens.
- Cytoplasm - the cytoplasm is a thick solution that fills the cell, and it is where all cellular reactions take place.
- Mitochondria - also referred to as the 'powerhouse of the cell'. It is responsible for the production of energy through cellular respiration.
- Rough Endoplasmic Reticulum (ER) - it is a network of membranes responsible for transport and storage of proteins. It is 'rough' as it contains ribosomes.
- Ribosomes - this are reponsible for the synthesis of proteins; ribosomes can be located in the rough ER.
- Smooth ER - a network of membranes responsible for lipid synthesis (as opposed to the rough ER).
- Chloroplast [plants only] - captures energy from sunlight and conducts photosynthesis. In essence, then, these are used to create glucose molecules.
- Golgi Apparatus - these are membrane-bound sacs responsible for packaging proteins prior to delivery to their designated destinations.
- Vacuole - more prominent in plants and is referred to as central vacuole; present in animals but very small. These are spaces for storage of food or water and sometimes even waste.
- Lysosome [animals only; uncommon in plants] - spherical vesicles containing hydrolytic enzymes that break down most molecules for degradation. They digest unwanted materials in the cytoplasm.
Cell has many different types of organelles such as
- Golgi apparatus which is responsible for modifying, sorting and packaging of proteins for secretion.
- Mitochondrion known as the powerhouse of the cell
- Ribosome synthesize proteins
- Vacuoles store food,water metabolic and toxic wastes
- Lysosomes break down the large food molecules into smaller molecules and also they digest old cell parts
- Nucleolus which makes ribosomes
- Cytoskeleton maintains the shapes of the cell
- Cytoplasm supports and protect the organelles inside the cell
- Endoplasmic reticulum (ER) aid in making proteins