Prodigy Sir, A slight nudge will open you,the great Rajarampedia,our own Hindupedia. YM
On Tue, Aug 22, 2023 at 10:34 AM Rajaram Krishnamurthy < [email protected]> wrote: > History of the Cell: Discovering the Cell > > 1 Yesterday a Q and A simply ran over on a topic that we are star dust. > It is nit amply evident from the mystery we are all in. So out of showing > the tail, let there not be darkness exposed sirs. > > 2 Initially discovered by Robert Hooke in 1665, the cell has a rich and > interesting history that has ultimately given way to many of today’s > scientific advancements. > > 3 Robert Hook refined the design of the compound microscope around 1665 > and published a book titled Micrographia which illustrated his findings > using the instrument. > > 4 Although they are externally very different, internally, an elephant, > a sunflower, and an amoeba are all made of the same building blocks. From > the single cells that make up the most basic organisms to the trillions > of cells that constitute the complex structure of the human body, each and > every living being on Earth is comprised of cells. This idea, part of > the cell theory, is one of the central tenants of biology. Cell theory also > states that cells are the basic functional unit of living organisms and > that all cells come from other cells. Although this knowledge is > foundational today, scientists did not always know about cells. > > 5 The discovery of the cell would not have been possible if not for > advancements to the microscope. Interested in learning more about the > microscopic world, scientist Robert Hooke improved the design of the > existing compound microscope in 1665. His microscope used three lenses and > a stage light, which illuminated and enlarged the specimens. These > advancements allowed Hooke to see something wondrous when he placed a piece > of cork under the microscope. Hooke detailed his observations of this tiny > and previously unseen world in his book, *Micrographia*. To him, the cork > looked as if it was made of tiny pores, which he came to call “cells” > because they reminded him of the cells in a monastery. > > 6 In observing the cork’s cells, Hooke noted in *Micrographia* that, “I > could exceedingly plainly perceive it to be all perforated and porous, much > like a Honey-comb, but that the pores of it were not regular… these pores, > or cells,…were indeed the first microscopical pores I ever saw, and > perhaps, that were ever seen, for I had not met with any Writer or Person, > that had made any mention of them before this…” > > 7 Not long after Hooke’s discovery, Dutch scientist Antonie van > Leeuwenhoek detected other hidden, minuscule > organisms—bacteria and protozoa. It was unsurprising that van Leeuwenhoek > would make such a discovery. He was a master microscope maker and perfected > the design of the simple microscope (which only had a single lens), > enabling it to magnify an object by around two hundred to three hundred > times its original size. What van Leeuwenhoek saw with > these microscopes was bacteria and protozoa, but he called these tiny > creatures “animalcules.” > > 8 Van Leeuwenhoek became fascinated. He went on to be the first to > observe and describe spermatozoa in 1677. He even took a look at the plaque > between his teeth under the microscope. In a letter to the Royal Society, > he wrote, "I then most always saw, with great wonder, that in the said > matter there were many very little living animalcules, very prettily > a-moving.” > > 9 In the nineteenth century, biologists began taking a closer look at > both animal and plant tissues, perfecting cell theory. Scientists could > readily tell that plants were completely made up of cells due to their cell > wall. However, this was not so obvious for animal cells, which lack a cell > wall. Many scientists believed that animals were made of “globules.” > > 10 German scientists Theodore Schwann and Mattias Schleiden studied > cells of animals and plants respectively. These scientists identified key > differences between the two cell types and put forth the idea that cells > were the fundamental units of both plants and animals. > > 11 However, Schwann and Schleiden misunderstood how cells grow. > Schleiden believed that cells were “seeded” by the nucleus and grew from > there. Similarly, Schwann claimed that animal cells “crystalized” from the > material between other cells. Eventually, other scientists began to uncover > the truth. Another piece of the cell theory puzzle was identified by Rudolf > Virchow in 1855, who stated that all cells are generated by existing cells. > > 12 At the turn of the century, attention began to shift toward > cytogenetics, which aimed to link the study of cells to the study of > genetics. In the 1880s, Walter Sutton and Theodor Boveri were responsible > for identifying the chromosome as the hub for heredity—forever linking > genetics and cytology. Later discoveries further confirmed and solidified > the role of the cell in heredity, such as James Watson and Francis Crick’s > studies on the structure of DNA. > > 13 The discovery of the cell continued to impact science one hundred > years later, with the discovery of stem cells, the > undifferentiated cells that have yet to develop into more > specialized cells. Scientists began deriving embryonic stem cells from mice > in the 1980s, and in 1998, James Thomson isolated human > embryonic stem cells and developed cell lines. His work was then published > in an article in the journal *Science*. It was later discovered that > adult tissues, usually skin, could be reprogrammed into stem cells and then > form other cell types. These cells are known as induced pluripotent stem > cells. Stem cells are now used to treat many conditions such as Alzheimer’s > and heart disease. > > 14 The discovery of the cell has had a far greater impact on science > than Hooke could have ever dreamed in 1665. In addition to giving us a > fundamental understanding of the building blocks of all living organisms, > the discovery of the cell has led to advances in medical technology and > treatment. Today, scientists are working on personalized medicine, which > would allow us to grow stem cells from our very own cells and then use them > to understand disease processes. All of this and more grew from a single > observation of the cell in a cork. [NATIONAL GEOGRAPHIC] > > 15 Cells are considered the basic units of life in part because they > come in discrete and easily recognizable packages. That's because all cells > are surrounded by a structure called the *cell membrane* — which, much > like the walls of a house, serves as a clear boundary between the cell's > internal and external environments. The cell membrane is sometimes also > referred to as the *plasma membrane*. > > 16 Cell membranes are based on a framework of fat-based molecules called > *phospholipids*, which physically prevent water-loving, or hydrophilic, > substances from entering or escaping the cell. These membranes are also > studded with proteins that serve various functions. Some of these proteins > act as gatekeepers, determining what substances can and cannot cross the > membrane. Others function as markers, identifying the cell as part of the > same organism or as foreign. Still others work like fasteners, binding > cells together so they can function as a unit. Yet other membrane proteins > serve as communicators, sending and receiving signals from neighboring > cells and the environment — whether friendly or alarming (Figure 1). > > 17 Within this membrane, a cell's interior environment is water based. > Called *cytoplasm*, this liquid environment is packed full of cellular > machinery and structural elements. In fact, the concentrations of proteins > inside a cell far outnumber those on the outside — whether the outside is > ocean water (as in the case of a single-celled alga) or blood serum (as in > the case of a red blood cell). Although cell membranes form natural > barriers in watery environments, a cell must nonetheless expend quite a bit > of energy to maintain the high concentrations of intracellular constituents > necessary for its survival. Indeed, cells may use as much as 30 percent of > their energy just to maintain the composition of their cytoplasm. > > 18 What Other Components Do Cells Have? > > As previously mentioned, a cell's cytoplasm is home to numerous functional > and structural elements. These elements exist in the form of molecules and > organelles — picture them as the tools, appliances, and inner rooms of the > cell. Major classes of intracellular organic molecules include nucleic > acids, proteins, carbohydrates, and lipids, all of which are essential to > the cell's functions. > > *19 Nucleic acids* are the molecules that contain and help express a > cell's genetic code. There are two major classes of nucleic acids: > *deoxyribonucleic > acid (DNA)* and *ribonucleic acid (RNA)*. DNA is the molecule that > contains all of the information required to build and maintain the cell; > RNA has several roles associated with expression of the information stored > in DNA. Of course, nucleic acids alone aren't responsible for the > preservation and expression of genetic material: Cells also use proteins to > help replicate the genome and accomplish the profound structural changes > that underlie *cell division*. > > *20 Proteins* are a second type of intracellular organic molecule. > These substances are made from chains of smaller molecules called *amino > acids*, and they serve a variety of functions in the cell, both > *catalytic* and structural. For example, proteins called *enzymes* convert > cellular molecules (whether proteins, carbohydrates, lipids, or nucleic > acids) into other forms that might help a cell meet its energy needs, build > support structures, or pump out wastes. > > *21 Carbohydrates*, the starches and sugars in cells, are another > important type of organic molecule. *Simple carbohydrates* are used for > the cell's immediate energy demands, whereas *complex carbohydrates* serve > as intracellular energy stores. Complex carbohydrates are also found on a > cell's surface, where they play a crucial role in cell recognition. > > 22 Finally, *lipids* or fat molecules are components of cell membranes > — both the plasma membrane and various intracellular membranes. They are > also involved in energy storage, as well as relaying signals within cells > and from the bloodstream to a cell's interior (Figure 2). > > 23 Some cells also feature orderly arrangements of molecules called > *organelles*. Similar to the rooms in a house, these structures are > partitioned off from the rest of a cell's interior by their own > intracellular membrane. Organelles contain highly technical equipment > required for specific jobs within the cell. One example is the > *mitochondrion* — commonly known as the cell's "power plant" — which is > the organelle that holds and maintains the machinery involved in > energy-producing chemical reactions > > [image: A pie slice diagram shows the proportion of water to typical > chemical components in a bacterial cell. Each chemical component is > color-coded and is labeled by name and percent.]Conclusion > > Cells are the smallest common denominator of life. Some cells are > organisms unto themselves; others are part of multicellular organisms. All > cells are made from the same major classes of organic molecules: nucleic > acids, proteins, carbohydrates, and lipids. In addition, cells can be > placed in two major categories as a result of ancient evolutionary events: > prokaryotes, with their cytoplasmic genomes, and eukaryotes, with their > nuclear-encased genomes and other membrane-bound organelles. Though they > are small, cells have evolved into a vast variety of shapes and sizes. > Together they form tissues that themselves form organs, and eventually > entire organisms. > > 24 Hence cells are not human. Humans have the value imbibed to the > cells. K Rajaram IRS 22 8 23 > > On Tue, 22 Aug 2023 at 07:20, Markendeya Yeddanapudi < > [email protected]> wrote: > >> >> >> -- >> *Mar*The Ego Shackle >> >> >> >> You are not singular. You are a plural of 10,000 trillion interacting >> cells, each cell a mini universe and ten times the number of cells >> bacteria, all making you the functioning and living you. Emotionally you >> are connected to the troposphere and cosmically to the whole universe, via >> quantum entanglement. If you can see everything, atoms, particles etc, then >> you confront the truth that you are not a static and unchanging ego but an >> interacting phenomenon in the universe. You cannot find yourself as that >> singular you is non-existent. The relational interactions among the cells >> and the bacteria continuously changes, we call it ageing. We are processes >> connected to the processes of nature. When you get absorbed into the >> general macro processes of nature, it is called death. >> >> The method of education is feeling and not the Cartesian tracing of >> causes and effects. The cause clusters and effect clusters continuously >> change; the clusters often mix up, creating many new process flows, in the >> invisible spectrum. >> >> When you adopt the method of feeling for education, then every aspect of >> nature becomes very important. You cannot destroy nature and call it >> development. >> >> What all you have to note is that you are actually part of the invisible >> Microcosm, and that you are basically abstract. If you adopt altruism as >> the basic motivation for living, then automatically you find that nature is >> approving you. Nature makes you succeed. The gigantic Microcosm makes you >> succeed and what we call miracles take over. You succeed in getting all >> your positive wants. But your personal success must synchronize with the >> success of nature in its macro march. You have to measure your success in >> terms of happiness. If you make nature happy, nature will make you happy. >> You don’t need complex mathematics to understand. Happiness is a positive >> emotion and no emotion can be quantified. >> >> Create the flow of happiness in nature. You automatically become happy >> and get what you need. >> >> YM >> > -- *Mar* -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/thatha_patty/CACDCHCLqmadjNVeABZKtqcJXtcxmH%2BgmyKKni_uD3vMGaSGUDA%40mail.gmail.com.
