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Standard Cell (SidraA)

Date: 09. January 2018

The cell is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life that can replicate independently, and cells are often called the "building blocks of life". The study of cells is called cell biology.

Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. While the number of cells in plants and animals varies from species to species, humans contain more than 10 trillion (1012) cells.

Organelles are parts of the cell which are adapted and/or specialized for carrying out one or more vital functions, analogous to the organs of the human body (such as the heart, lung, and kidney, with each organ performing a different function).

In complex multicellular organisms, cells specialize into different cell types that are adapted to particular functions. In mammals, major cell types include skin cellsmuscle cellsneuronsblood cellsfibroblastsstem cells, and others. Cell types differ both in appearance and function, yet are genetically identical.

Cell division involves a single cell (called a mother cell) dividing into two daughter cells. 

In meiosis, the DNA is replicated only once, while the cell divides twice. DNA replication only occurs before meiosis IDNA replicationdoes not occur when the cells divide the second time, in meiosis II.

cytoplasm. The ER has two forms: the rough ER, which has ribosomes on its surface that secrete proteins into the ER, and the smooth ER, which lacks ribosomes. The smooth ER plays a role in calcium sequestration and release.

Mitochondria generate energy for the cell. Mitochondria are self-replicating organelles that occur in various numbers, shapes, and sizes in the cytoplasm of all eukaryotic cellsRespiration occurs in the cell mitochondria, which generate the cell's energy by oxidative phosphorylation, using oxygen to release energy stored in cellular nutrients (typically pertaining to glucose) to generate ATP.

Two different kinds of genetic material exist: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Cells use DNA for their long-term information storage. The biological information contained in an organism is encoded in its DNA sequence. RNA is used for information transport (e.g., mRNA) and enzymatic functions (e.g., ribosomal RNA). Transfer RNA (tRNA) molecules are used to add amino acids during protein translation.

Cell surface receptors (membrane receptorstransmembrane receptors) are receptors that are embedded in the membranes of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the extracellular space. The extracellular molecules may be hormonesneurotransmitterscytokinesgrowth factorscell adhesion molecules, or nutrients; they react with the receptor to induce changes in the metabolism and activity of a cell. In the process of signal transductionligand binding affects a cascading chemical change through the cell membrane.

Afzal, Sidra
  • Academics: Pharm D
  • Specialization: Pharmacology
  • Current: Medical Editor
  • Company: Manan Learning Solutions
  • Location: Rawalpindi, Pakistan
  • Clinical / Teaching Years: 1 / 1
  • Course: Pharmacology

Ms. Sidra Afzal has completed her Pharm.D from Hamdard University in 2017. She joined Global Pharmaceutical as a Production Pharmacist right after completion of her degree. Later she joined Davis Pharmaceutical as a Quality assurance Inspector. She has Teaching Experience of 1 year. 

Currently she is serving as a Medical Content Editor at Manan Learning Solutions.

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