INTRODUCTION
The basic structural and functional unit of living organisms called cells are incredibly magnificent,complex and dynamic entities.They being so tiny have the ability to perform wide variety of processes like growing,dividing,responding to stimuli thus sustaining life.All these cellular processes take place in the specialized compartments known as Cell Organelles which are tiny membrane bound structures found in cells performing specialized functions required for the survival and operation of the cell.All the organelles work together in a coordinated manner to maintain the homeostasis of the body,their study has revolutionized our understanding of cellular biological functions.The nucleus holds the genetic material and the energy generation is done by mitochondria,apart from these two each and every organelle plays a crucial role in maintaining the homeostasis in cells.
In this blog,we will discuss about all the organelles constituted in a cell to gain knowledge and appreciation for the complexity and beauty of cells.
TYPES OF CELL ORGANELLES
1.Nucleus
☆The controlled center for all the cellular activities with the membrane bound structure constituting genetic material(DNA) and it is onset of the largest and most prominent among all the organelles in eukaryotic cells.
☆Structure of Nucleus:
•Nuclear envelope:The double membrane structure surrounding the nucleus which regulates the movement of materials in and out of the nucleus.
•Nucleolus:The region where the synthesis of ribosomes takes place.
•Chromatin:The makers of genetic material,generally complex of proteins and DNA.
☆Functions of nucleus
•It stores the genetic information of the cell in the form of DNA.
•The transcription of DNA into RNA is controlled by this organelle thus regulating gene expression.
•It plays an assuring role in the replication of genetic material (even distribution between daughter cells) during cell division.
2.Mitochondria
☆The organelle which is known as the powerhouse of the cell as it generates maximum amount of energy that a cell requires to operate and carry out it's functions,it is present in cells if most eukaryots including plants,animals and fungi.
☆Structure of Mitochondria :
•Outer Membrane: Regulation of materials in and out of the Mitochondria is possible because of this permeable membrane surrounding it.
•Inner Membrane : The site for the cellular respiration and an impermeable folded membrane.
•Mitochondrial Matrix : The empty space inside it where the citric acid cycle and oxidation of fatty acids takes place.
•Cristae: The membrane which increases the surface area for cellular respiration as they are the folded structures.
☆Functions of Mitochondria :
•The breakdown of glucose and other inorganic material into the ATP (adenosine triphosphate) through cellular respiration which is an energy producing process is possible because of mitochondria.
•It plays a crucial role in the regulation of cell growth and division by controlling the energy available to the cell.
3. Endoplasmic Reticulum (ER)
☆The complex network of membranous tubules and sacs in the cell.
☆Structure of Endoplasmic Reticulum (ER)
•Smooth Endoplasmic Reticulum (SER): The membrane lacks ribosomes and is involved in lipid synthesis and detoxification.
•Rough Endoplasmic Reticulum (RER):
The membrane is covered by ribosomes which are responsible for protein synthesis.
☆Functions of Endoplasmic Reticulum :
•It is involved in synthesis and folding if proteins which are then thrown out of the cell.
•It is involved in the synthesis and metabolism of lipids including cholesterol and phospholipids.
•It acts as a reserve forest calcium ions,releasing them into cytosol whenever required.
•It is involved in the detoxification of harmful substances and activation of cellular defense mechanisms.
4. Ribosomes
☆The organelles playing a vital role in the synthesis of proteins that is translating messenger RNA into specific sequence of amino acids are the smallest,complex organelles found throughout the cytoplasm in the cell.
☆Structure of Ribosomes:
•Large and Small Subunits: The two units,large and small come together to form a functioning ribosome.
•Ribosomal RNA and Proteins: It is composed of rRNA and protein which work together to facilitate protein synthesis.
☆Functions of Ribosomes :
•The formation of polypeptide chain by translating mRNA into specific sequence of amino acids.
•They play a role of Catalysts in the formation of polypeptide chain by creating peptide bonds.
•They help in the creation of three dimensional structure of protein by facilitating folds in the protein.
5. Lysosomes
☆The membrane bound organelle playing a crucial role in cellular digestion,defense and recycling and us found in the cells of most of the eukaryots.
☆Structure of Lysosomes:
•Membrane: It has a single membrane which surrounds the digestive enzymes and substrates.
•Digestive Enzymes: Proteases,lipases and glycosidases are the digestive enzymes present in lysosomes.
•Acidic Environment : The pH of lysosomes is around 4.5-5.0 which is essential for the activity of digestive enzymes.
☆Functions of Lysosomes :
•It constitutes digestive enzymes which break down and Recycle cellular waste,foreign substances and damaged organelles.
•It aids in the degradation of proteins which are damaged or no longer needed.
•It defends the cell by breaking and eliminating the pathogens and foreign substances.
•The cellular components like proteins,lipids and carbohydrates are recycled to conserve energy and resources.
6. Golgi Apparatus
☆The organelle involved in packaging,processing and modification of proteins and lipids synthesized by Endoplasmic Reticulum, and a complex organelle found in all eukaryots.
☆Structure of Golgi Apparatus:
•Stacks of Cisternae : It consists of sacs of flat membranous sacs called cisternae.
•Vesicles or Tubules : They facilitate the transport of molecules within the organelle.
☆Function of Golgi Apparatus:
•Glycosylation and phosphorylation,the processes of modification of carbohydrates and phosphates takes place in this organelle.
•It sorts and packages proteins and lipids into vesicles for transport to other parts of the cell or for secretion outside the cell.
•It is also involved in the synthesis and modification of lipids,including glycolipids and sphingolipids.
7. Cytoskeleton
☆The eukaryotic cells get their structural support,shape and movement by the presence of dynamic network of filaments and tubules.
☆Structure of Cytoskeleton:
•Microtubules:The formation of cilia and flagella,organization of organelles and maintainence of cell shape is due to these hollow tunes consisting of tubulin proteins.
•Microfilaments:The muscle contractions,cell signaling and cell divison is due to the presence of thin filaments constituting actin protein.
•Intermediate Filaments:The mechanical support and cell shape is maintained by lamin and keratin proteins.
☆Functions of Cytoskeleton:
•It provides mechanical support and maintains the shape of the cell.
•It plays a vital role in movement and migration of the cell.
•It helps in the organization and positioning of the organelles within the cell.
•It is involved in the division and signaling of the cell
8.Peroxisomes
☆The organelle which plays a vital role in cellular detoxification, metabolism, and energy production is a small, membrane-bound organelle found in the cells of most eukaryotes.
☆Structure of Peroxisomes:
•Single Membrane: They have a single membrane surrounding the organelle.
• Crystalline Core: They often have a crystalline core, which is constituted by enzymes involved in detoxification and metabolism.
☆Functions of Peroxisomes:
• They break down fatty acids and amino acids which produce energy for the cell.
• They contain enzymes that detoxify harmful substances like hydrogen peroxide and other reactive oxygen species.
• They are involved in the glyoxylate cycle, that is very essential for the metabolism of certain amino acids and sugars.
9. Centrioles
☆The organelle which plays a crucial role in organization of microtubules, which are essential for maintaining cell shape, organizing organelles, and facilitating cell division are small, cylindrical organelles found in the cells of most eukaryotes
☆Structure of Centrioles:
•Cylindrical Shape: They are cylindrical in shape, typically 200-250 nm in length and 150-200 nm in diameter.
•Microtubule Triplets: They constitute microtubule triplets, which are arranged in a specific pattern.
☆Functions of Centrioles:
•They act as microtubule organizing centers (MTOCs), nucleating and anchoring microtubules.
•They are involved in the formation of cilia and flagella, that are essential for cell movement and sensing.
•They play a vital role in cell division, particularly in the formation of the spindle apparatus.