There are mainly three parts of a cell: cell membrane (works as a gate keeper and controls what can come in and go out of the cell), nucleus (controls the functions of the cell) and cytoplasm (fluid which helps all the components of cell to move). But when we go in depth cell can further divide into 14 parts which includes: cell membrane, nucleus, nuclear membrane, nucleoplasm, nucleolus, cytoplasm, endoplasmic reticulum, ribosomes, golgi bodies, vacuoles, mitochondria, plastids, chloroplast and cell wall.
Cell drives from Latin word “cella” means “small room”. Cell is the smallest and very basic unit of life as it gives living thing a structure and controls all the functions of its body. Every living thing either it is composed on single cell (bacteria) or multiple cells (human) is called Organism.
Cells are generally classified into two types:
Prokaryotic cell is very simple and very small in size. It does not contain any membrane
-bounded organelles mainly nucleus. The organisms lie on this group is single cellular organisms, like Bacteria and Archaea. Prokaryotic cell composed on:
Nucleoid, ribosomes, cell wall/cell membrane, capsule, fimbriae, pili, flagella.
Eukaryotic cell is very large and complex cell. It contains all components of cell either it is membrane bounded or not. The organisms lie on this group are both single and multi-cellular organisms. For example: Human, plants, animals, fungi and algae. The components of eukaryotic cell includes: nucleus, nucleolus, cell membrane/cell wall, ribosomes, mitochondria, cytoplasm, endoplasmic reticulum and vacuoles.
Cell is made up of different molecules, carbohydrates, protein and acids. It contains following components:
Cell membrane is a shield of cell which is made up of plasma. It is also known as plasma membrane it works as a guard which protects cell and its components from outside environment. It controls what can come inside and go out from cell. It also provide food or nutrition inside and move its waste.
Following is the typical structure of cell membrane:
- Carbohydrates (Present on extracellular sides and attached with proteins.)
- Integral protein (Encapsulated with phospholipid bi-layers.)
- Peripheral protein (Present on either inner or outer surface of phospholipids bi-layers.)
- Cholesterol (Stick between the hydrophobic tails of membrane.)
- Phospholipids (Main foundation of cell membrane.)
Carbohydrates are one of the major part of cell membrane which is present on the surface of cell membrane and bound with protein. It can either straight or in branch and like ID marker it helps cell to recognize each other.
Membrane protein are mainly divided into two categories:
• Integral protein
• Peripheral protein
Integral protein is integrated to the membrane and attached them to the hydrophobic core of phospholipids. It helps in transportation of molecules between cell and also help in cell to cell recognition. It can be further divided in to two type:
• Integral polytopic protein can move across the membrane at once.
• Integral monotopic protein is bound with one side of membrane and cannot move across the membrane. There are four types of interaction:
- Amphipathic helix parallel
- Hydrophobic loop
- Covalently bound
- Electrostatic interaction
Peripheral protein found on the surface of cell membrane and attached either integral protein or phospholipids. It do not stick to the hydrophobic core of the membrane that allow it to be more loosely bound. It allow cells to communicate each other and share information.
Cholesterol is embedded in bi-layer of phospholipids and keeps membrane maintain by reducing the transmission of molecules by increasing fluidity.
It is the most critical component of cell membrane which controls the passage of molecules into and out of the cell because it embedded by protein which holds selective passage of molecules. It consists of a hydrophilic head (water loving) and hydrophobic tail (water phobic).
Nucleus is the major part of the cell as it controls all the functions regarding its growth and reproduction. It is also one of the largest part of the cell which occupied 10th part of entire cell space. It is also bounded by a membrane called Nuclear Membrane. It contains chromosomes and genetic material that define structure and function of a Eukaryotic cell.
The spherical-shaped organelle works as an informative and administrative chamber of the cell which consists on following components:
• Nuclear membrane
Nuclear membrane is also known as nuclear envelop. It is double membrane which protects cell-nucleus and separates chromosomes with rest of the cell. The outer membrane contain small pores which transmit proteins to the nucleus. Just like cell membrane nuclear membrane also works as the shield but the difference between both biological membranes is: cell membrane protects entire cell from its outer environment while nuclear membrane separates nucleus and its internal components from other components of cell.
Chromosomes is the major component of a nucleus which is long chain of DNA molecules. Chromosome is the tread like structure having DNA molecules embedded in it which contain the information or characteristics of living being which make everyone unique from other.
There are following four types of chromosomes:
• Sub metacentric
The nucleus of large eukaryotic organisms like human or animals contains 23 chromosomes in which 22 pair of chromosomes called Autosomes while one is the genetic determination chromosomes (X and Y). Each parent pass half of their chromosomes which are then taken by their offspring so they can inherit half from mother and half from father.
Similarly like cell’s cytoplasm, nucleus also contain a gel-like substance known as nucleoplasm which dissolves other components of nucleus i.e. chromosomes and nucleolus. Nucleoplasm is protected by envelop called nuclear envelop or nuclear membrane. It helps in maintain the shape and structure of nucleus and also helps in transportation of molecules.
Nucleolus is the brain of nucleus which helps in protein formation and RNA production these are very tiny size yet an important component of nucleus.
Cytoplasm is the liquid substance filled in the cell which helps to maintain the structure of cell. All organelles except nucleus and mitochondria because these two already surrounded by membrane. It is composed of salt, water and protein.
Endoplasmic reticulum is a membrane which form a series of sac within cytoplasm. It is very helpful in protein production, folding and its transportation. Endoplasmic reticulum (ER) is further divided into two subunits:
• Rough endoplasmic reticulum
• Smooth endoplasmic reticulum
Rough endoplasmic reticulum is the outer surface of endoplasmic reticulum it contains small pores called Ribosomes which give it rough appearance. The basic function of rough endoplasmic reticulum is to combine protein and send it to some destination such as cell membrane, cell exterior and endoplasmic reticulum itself.
Smooth endoplasmic reticulum is the inner surface of ER which is comparatively smooth. It produces lipids (cholesterol and phospholipids) which helps in production of outer surface of cell.
Golgi bodies also known as golgi apparatus or golgi complex is the membrane bounded organelle of an eukaryotic cell which is present in cytoplasm near cell nucleus. It is responsible of making packages of proteins and lipids and pack into the vesicles for deliver to the destination. Golgi bodies contains folding which is called cisternae. According to its function there are five functional area of golgi bodies:
• Cis-golgi: area for biochemical modifications.
• Medial-golgi: area for biochemical modifications.
• Trans-golgi: area for biochemical modifications.
• Cis-golgi network: entry point of golgi bodies, it establish connection with endoplasmic
• Trans-golgi network: exit point of golgi bodies, it is responsible for sorting and packaging of proteins and lipids and send to the destination.
Ribosomes is the small pores attached either with endoplasmic reticulum or float in cytoplasm. It is the molecular machine found in both prokaryotic and eukaryotic cell. It helps in protein formation which is necessary for many cell activities.
Vacuoles are also membrane bounded organelles which are present in eukaryotic cell. In animal cell vacuoles are small and responsible for remove wastes of cells. While in plant cell vacuoles are comparatively large and responsible for maintain water level.
Mitochondria is the double-membrane bounded organelle in all eukaryotic cell and in some of the prokaryotic cell also. It is responsible for give energy to the cell that’s way it is known as the power house of the cell. Cellular respiration and food oxidation is take place in mitochondria.
Plastids are also membrane-bounded organelle which is present in plant cell. It contain pigments (chlorophyll) which is necessary for photosynthesis. It is responsible for determination of cell’s color.
It is the organelle of plant cell which play an important role in photosynthesis.it is responsible to convert light energy into the energy which is taken by plants as their food.
Cell wall is also the organelle of plant cell. It is outer sometime hard and sometimes flexible layer of cell which is responsible to give structure to the cell also provide the protection to cell from outer environment.
A typical animal cell contain following types of cell:
• Epithelial cell
• Nerve cell
• Muscle cell
• Connective tissue cell
The main components of cell are: cell membrane, nucleus and cytoplasm. Cell membrane is the protection shield of entire cell which protects cell from its environment. Nucleus is the brain of cell which contains all the information regarding characteristics of cell while cytoplasm is the jelly like substance which contain all the organelles float in it.
Membrane-bounded organelles are protected through shield which protect them from outside environment while non-membrane bounded organelles do not contain any shield.
Prokaryotic organisms are single cellular organisms and does not contain any membrane bounded organelles. For example they do not have nucleus, mitochondria, vacuoles etc.
Cell is the basic unit of life it is the membrane bounded unit which contains many organelles having different functions. A single cell is itself a complete life as some organisms which lies in prokaryotic group of organisms contains only one cell.
Cell composed of some of the organic molecules such as proteins, lipids, nucleic acid and carbohydrates.
Every living organism is consists on cell that’s why we can say that cell is the basic unit of life. Organism can be single cellular (one cell) or multicellular (multiple cells). Single cellular organism’s cell structure is very simple and small in size and cannot be seen from naked eyes while the cell of multicellular organisms are complex and contain different organelles some of them are bounded by membrane while other are not. Each organelle have different function or responsibility these organelles are known as the “part of the cell”.