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Are cells really the basic unit of all life?

Are cells really the basic unit of all life?


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Please see comments as to the appropriateness of this question on biology SE.

All known life on Earth is made up of cells. It is thus safe to say that all known life is characterized by the presence of cells. But is having cells as a basic unit a requirement for life?

I'm thus asking if life is currently existent and/or possible without biomembranes, and to what degree cells actually matter in our present understanding of life.

An all-encompassing, comprehensive and cited answer would be very much appreciated.


According to Gerry Joyce: "Life is a self-sustained chemical system capable of undergoing Darwinian evolution."

From a meta-analysis of 123 definitions of life: "Life is metabolizing material informational system with ability of self-reproduction with changes (evolution), which requires energy and suitable environment."

According to Alexander Oparin: “Any system capable of replication and mutation is alive”.

At hand are some key elements in order to match these criteria. Maintaining a Darwinian cycle requires replication, mutation, and selection. Thus, we can break down the above into 5 criteria (personal communication with Gerry Joyce).

  • Life stores information
  • Life reproduces its information
  • Life alters that information
  • Life does something with that information (uses energy)
  • Life does all of this in a self-sustained manner

I would point out that the above criteria is quite different from what is currently on wikipedia described by metabolism and homeostasis. There are certainly additional criteria that certainly raise the threshold for what may be considered life. The common discussion revolves around viruses which do many of these things but not in a self-sustained way.

The question at hand then asks if cells are the minimum unit of life? What makes a cell a cell is that there is compartmentalization. The underlying reason behind this compartment is due to the necessity of tying the phenotype to the genotype. Paraphrasing using our definition of life, it links the information with the function that the information carries out. In the modern biological scheme, it keeps the proteins (phenotype) with the DNA (genotype).

The necessity of compartmentalization is negated when the phenotype is already linked with the genotype. The most frequent example is RNA where the material that carries the information is also the material that carries out its function. It tend, is reasonable to hypothesize that life can be made entirely with RNA without the need for compartmentalization (although compartmentalization certainly helps see Paegal and Joyce and Chen and Szostak).

Recent experiments by Gerry Joyce and others have been able to satisfy several of the requirements of life. The have self-replicating RNAs, that store information, that reproduce their information, that introduce alterations to their information, and do it in a self-sustained manner. What Gerry and his colleagues agree on is that their current self-replication Ribozyme system doesn't do anything particularly novel. However, by introducing a larger variety of functional elements to their ribozymes perhaps they will.


Life is a physical entity that creates copies of itself,
sometimes in a slightly changed form.

That's it.

A cell is not the basic unit of a life but a large number of molecules that have bonded together to reap the benefits of specialization. Like what is happening today, humans coming together to form a society which collectively starts to function like a single living organism again.

So no, a cell is a far cry from being the basic unit of life, it is a very advanced form of life.

All it takes for life to start is for a single self replicating molecule to form, that's it.
Evolution takes over from there.


Cell (biology)

The cell (from Latin cella, meaning "small room" [1] ) is the basic structural, functional, and biological unit of all known organisms. Cells are the smallest units of life, and hence are often referred to as the "building blocks of life". The study of cells is called cell biology, cellular biology, or cytology.

Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. [2] Most plant and animal cells are only visible under a light microscope, with dimensions between 1 and 100 micrometres. [3] Electron microscopy gives a much higher resolution showing greatly detailed cell structure. Organisms can be classified as unicellular (consisting of a single cell such as bacteria) or multicellular (including plants and animals). [4] Most unicellular organisms are classed as microorganisms.

The number of cells in plants and animals varies from species to species it has been estimated that humans contain somewhere around 40 trillion (4×10 13 ) cells. [a] [5] The human brain accounts for around 80 billion of these cells. [6]

Cells were discovered by Robert Hooke in 1665, who named them for their resemblance to cells inhabited by Christian monks in a monastery. [7] [8] Cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells. [9] Cells emerged on Earth at least 3.5 billion years ago. [10] [11] [12]


The organisms consisting of many cells are known as multicellular organisms. E.g. human being, animals, birds, etc.

Each living cell has the aptitude to perform certain basic functions that are characteristic of all living forms.

Each such cell has certain specific components within it known as cell organelles.

Different types of cells have different function and each cell organelle performs a special function.

These organelles collectively constitute the basic unit of life known as cell.

All cells are found to have the same organelles, irrespective of their different functions and the organism they found in.


History of the Cell: Discovering the Cell

Initially discovered by Robert Hooke in 1665, the cell has a rich and interesting history that has ultimately given way to many of today&rsquos scientific advancements.

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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.

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 &ldquocells&rdquo because they reminded him of the cells in a monastery.

In observing the cork&rsquos cells, Hooke noted in Micrographia that, &ldquoI 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&hellip these pores, or cells,&hellipwere 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&hellip&rdquo

Not long after Hooke&rsquos discovery, Dutch scientist Antonie van Leeuwenhoek detected other hidden, minuscule organisms&mdashbacteria 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 &ldquoanimalcules.&rdquo

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.&rdquo

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 &ldquoglobules.&rdquo

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.

However, Schwann and Schleiden misunderstood how cells grow. Schleiden believed that cells were &ldquoseeded&rdquo by the nucleus and grew from there. Similarly, Schwann claimed that animal cells &ldquocrystalized&rdquo 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.

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&mdashforever linking genetics and cytology. Later discoveries further confirmed and solidified the role of the cell in heredity, such as James Watson and Francis Crick&rsquos studies on the structure of DNA.

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&rsquos and heart disease.

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.

Robert Hook refined the design of the compound microscope around 1665 and published a book titled Micrographia which illustrated his findings using the instrument.


ClearlyExplained.com

In biology, the cell (from Latin cella, meaning "small room") is the basic structural, functional and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology.

Cells consist of a protoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.

Organisms can be classified as unicellular (consisting of a single cell including most bacteria) or multicellular (including plants and animals). While the number of cells in plants and animals varies from species to species, humans contain about 100 trillion (10 14 ) cells.

diagram of an average prokaryotic cell. image: wikipedia

Most plant and animal cells are visible only under the microscope, with dimensions between 1 and 100 micrometres.

The cell was discovered by Robert Hooke in 1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that:

  • all organisms are composed of one or more cells,
  • that all cells come from preexisting cells,
  • that vital functions of an organism occur within cells, and
  • that all cells contain the hereditary information necessary for
    • regulating cell functions and for
    • transmitting information to the next generation of cells.

    Cells emerged on Earth at least 3.5 billion years ago.

    Anatomy of cells- or what's inside and on the surface of cells


    What is cell theory?

    1. A cell is the basic structural and functional unit of living organisms. When you define cell properties, you define the properties of life.
    2. The activity of an organism depends on both the individual and the collective activities of its cells.
    3. According to the principle of complementarity of structure and function, the biochemical activities of cells are dictated by their shapes or forms, and by the relative number of their specific sub-cellular structures.
    4. Continuity of life from one generation to another has a cellular basis.

    Cells are the basis of life. Some connect body parts and store nutrients, others fight disease and transport gases. Some cells gather information and control certain body functions, while specialized cells are used for reproduction.

    These concepts will be expanded on as we progress and links will be posted to new material as it’s available. For now, lets begin with the idea that the cell is the smallest living unit. No matter its form, or how it behaves, the cell is a microscopic package that contains all the necessary parts to survive in a changing world. This is why the loss of cellular homeostasis underlies virtually every disease known to man.

    There are trillions of cells in the human body. These include over 200 different cell types that vary greatly in size, shape, and function. Red blood cells are disc-shaped, nerve cells branch, and kidney tubule cells are cubed. These are just a few examples of the shape cells take. Cells vary in length as well – ranging from 2 micrometers in the smallest cells to over a meter in the nerve cells you wiggle your toes with. Generally, a cell’s shape reflects its function. For example, the epithelial cells that line the inside of your cheek are flat and fit closely together like floor tile, forming a living barrier that protects underlying tissues from bacterial invasion. We know this thanks to research that has been able to be done due to the medical equipment that we have today. Things like centrifuge tubes (a centrifuge tube is one of the most versatile consumable around) and other specialized equipment makes this sort of research easily accessible.


    A Biologist Explains: What Is Life?

    Although biology is the study of life, even biologists don't agree on what 'life' actually is. While scientists have proposed hundreds of ways to define it, none have been widely accepted. And for the general public, a dictionary won't help because definitions will use terms like organisms or animals and plants -- synonyms or examples of life -- which sends you round in circles.

    Instead of defining the word, textbooks will describe life with a list of half a dozen features based on what it has or what it does. For what life has, one feature is the cell, a compartment to contain biochemical processes. Cells are often listed because of the influential cell theory developed in 1837-1838, which states that all living things are composed of cells, and the cell is the basic unit of life. From single-celled bacteria to the trillions of cells that make up a human body, it does seem as though all life has compartments.

    A list of features will also mention what life does -- processes like growth, reproduction, ability to adapt and metabolism (chemical reactions whose energy drives biological activity). Such views are echoed by experts such as biochemist Daniel Koshland, who listed his seven pillars of life as program, improvization, compartmentalization, energy, regeneration, adaptability and seclusion.

    But the list approach is let down by the fact it's easy to find exceptions that don't tick every box on a checklist of features. You wouldn't deny that a mule -- the hybrid offspring of a horse and donkey -- is alive, for example, even though mules are usually sterile, so no tick for reproduction.

    Entities on the border between living and non-living also undermine lists. Viruses are the most well-known fringe case. Some scientists claim that a virus isn't alive as it can't reproduce without hijacking the replication machinery of its host cell, yet parasitic bacteria such as Rickettsia are considered alive despite being unable to live independently, so you can argue that all parasites can't live without hosts. Meanwhile Mimivirus -- a giant virus discovered in an amoeba that's large enough to be visible under a microscope -- looks so much like a cell that it was initially mistaken for a bacterium. Humans are also creating fringe cases -- designer organisms like Synthia, which has few features and wouldn't survive outside a lab -- through synthetic biology.

    Are entities such as viruses really life-forms, or merely life-like? Using a list definition, that largely depends on the criteria you choose to include, which is mostly arbitrary. An alternative approach is to use the theory considered to be a defining feature of life: Charles Darwin's theory of evolution by natural selection, the process that gives life the ability to adapt to its environment. Adaptability is shared by all life on Earth, which explains why NASA used it as the basis for a definition that might work in helping to identify life on other planets. In the early 1990s, an advisory panel to NASA's astrobiology program, which included biochemist Gerald Joyce, came up with a working definition: Life is a self-sustaining chemical system capable of Darwinian evolution.

    The 'capable' in NASA's definition is key because it means astrobiologists don't need to watch and wait for extraterrestrial life to evolve, just study its chemistry. On Earth, the instructions for building and operating an organism is encoded in genes, carried on a molecule like DNA, whose information is copied and inherited from one generation to the next. On another world with liquid water, you would look for genetic material that, like DNA, has a special structure that might support evolution.

    Detecting alien life is a harder task than collecting samples, however, as illustrated by the Viking mission. In 1977, NASA put landers on Mars and performed a variety of experiments to try and detect signs of life in the Martian soil. The results were inconclusive: while some tests returned positive results for the products of chemical reactions that might indicate metabolism, others were negative for carbon-based organic molecules. Decades later, astrobiologists are still limited to looking for life indirectly, searching for biosignatures -- objects, substances or patterns that might have been produced by a biological agent.

    Given that scientists who look for life are fine with signatures, some say we don't actually need a definition. According to philosopher Carlos Mariscal and biologist W Ford Doolittle, the problem with defining life arises from thinking incorrectly about its nature. Their strategy is to search for entities that resemble parts of life and to think of all life on Earth as an individual. That solution might suit astrobiologists, but it wouldn't satisfy people who want to know whether or not something strange, like a virus, is alive.

    A major challenge for both detecting and defining life is that, so far, we've only encountered one example in the Universe: terrestrial life. This is the 'N = 1 problem'. If we can't even agree on the distinction between living and non-living things, how can we expect to recognize weird forms of life?

    It's life, but not as we know it

    As science hasn't provided conclusive proof of extraterrestrials, we must turn to science fiction, and few series have explored such possibilities better than Star Trek: The Next Generation. The voyages of the starship Enterprise and "its continuing mission to explore strange new worlds and seek out new life and new civilizations" gave us everything from the god-like being Q to a huge Crystalline Entity that converts living matter to energy (a kind of metabolism). Perhaps most interestingly, as researchers get closer to creating an artificial intelligence that's smarter than a person, there's Data -- an android who had to prove human-like sentience but didn't reproduce until he built his own daughter. Would a god who exists beyond time, a spaceship-sized crystal or a robotic AI be considered 'alive'?

    Is Data from 'Star Trek: The Next Generation' alive?

    'What is life?' is not simply a question for biology, but philosophy. And the answer is complicated by the fact that researchers from different fields have differing opinions on what they believe ought to be included in a definition. Philosopher Edouard Machery discussed the problem and presented it as a Venn diagram with circles for three groups -- evolutionary biologists, astrobiologists and artificial-life researchers -- using hypothetical features upon which they would converge (some biologists think viruses are alive while others believe the cell is essential, so assuming members would agree is controversial). Machery claimed that no criteria could fall within the overlap of all three circles, concluding that "the project of defining life is either impossible or pointless."

    But while philosophers can sidestep the problem without consequences, the conclusion that it's futile to define life is both unsatisfying and frustrating for regular folk (and also for those like me, who care about the public understanding of science). Regardless of whether researchers ever reach a consensus on a scientific definition, we still need a folk definition for practical purposes -- a sentence to explain the concept of life that the average person can understand.

    Life may be a fuzzy concept, but that doesn't mean its meaning should be vague. As computational biologist Eugene Koonin pointed out, defining life isn't scientific because it's impossible to disprove, as we can always find an entity that meets all criteria but is 'clearly' not alive, or lacks certain features but is 'obviously' a life-form, and so "some kind of intuitive understanding of the living state superseding any definition is involved [. ] we seem to 'know it when we see it'." Koonin focused on whether a definition can provide biological insights (such as identifying novel life-forms) but mentions another area where defining life might be useful: "better teaching of the fundamentals of biology."

    So how do we get a definition that teaches biology? This is partly an exercise in semantics. First, a popular definition should avoid technical jargon and use everyday language. Next we need a starting point. Since Aristotle first tried to define life around 350 BC, thinkers have engaged in seemingly endless philosophical discussions, In 2011, biophysicist Edward Trifonov tried to break the deadlock by comparing 123 definitions to find a consensus, grouping words into clusters and counting the ones used most frequently to produce a minimal or concise definition: Life is self-reproduction with variations.

    The 'variations' in Trifonov's definition are mutants, the result of mutations (errors in copying) that occur during reproduction, which is what creates the variety in a population that allows 'survival of the fittest' individuals through evolution by natural selection. While Trifonov's consensus and NASA's working definition don't use the same words, they're two sides of the same coin and share a central concept: life is able to adapt to its environment.

    Darwinian evolution is the way that life as we know it adapts. But what about things that might use alternative mechanisms of adaptation? As a narrow definition will exclude fringe cases and being broad would let us include a wide range of potential life-forms, our popular definition drops Trifonov's inclusion of 'self-reproduction' (allowing for immortal AIs that don't need to replicate) and also NASA's requirement for a 'chemical system' (allowing for organisms that don't carry genes on a DNA-like molecule). An 'environment' implies a habitat or ecosystem, not simply the surroundings, which rules-out a robot that adjusts its body to traverse a terrain and virtual objects that navigate a digital domain.

    Lastly, we need a word for the 'thing' we describe as living. Scientists and philosophers use 'entity' without acknowledging that, just as a dictionary uses 'organism', it's effectively a fancy synonym for 'life' (Can you think of an 'entity' that doesn't imply some sort of life-form?) This slight logical circularity may not be ideal, but I can't think of a better option. An entity is a self-contained thing, which means the word can work whatever the level -- whether that's an individual organism, an AI, or all life on a planet.

    Any definition should be necessary and sufficient, but it's important to first identify for whom. Because this article is aimed at a general audience (non-scientists), the goal is a folk definition. So what is life? Here's a suggestion:

    Life is an entity with the ability to adapt to its environment.

    While I think my 'popular definition' makes intuitive sense, it could still join the hundreds of scientific proposals that have failed to find acceptance. Unlike dictionary definitions, at least it isn't wrong, but only time will tell whether people think it's actually right.


    Cell biology

    Cell biology is the academic discipline that studies the basic unit of living things, cells. Cells are the smallest independently functioning unit in the structure of an organism and usually consist of a nucleus surrounded by cytoplasm and enclosed by a membrane. Cell biology examines, on microscopic and molecular levels, the physiological properties, structure, organelles (such as nuclei and mitochondria), interactions, life cycle, division and death of these basic units of organisms. Cell biology research extends to both the great diversity of single-celled organisms, such as bacteria and the many specialized cells in multicellular organisms, such as animals and plants.

    The field of cell biology traditionally has focused on questions concerning how the various organelles work and work together, how these cellular processes are regulated and how the various cells within the organism communicate with each other. Understanding the composition of cells and how cells work is fundamental to all the biological and medical sciences. Examining the similarities and differences between cell types is particularly important to the fields of cell and molecular biology, because the principles learned from studying one cell type can be generalized to other cell types. Research in cell biology closely is related to genetics, biochemistry, molecular biology and developmental biology.

    The structures and functions within a cell often are compared to similar activities in a typical city. Mitochondria are the cell’s energy plants, plant chloroplasts are solar energy plants, chromosomes contain the original blueprints of the city, the endoplasmic reticulum represents the road system, Golgi apparatus is the post office and the nucleus is city hall. Proteins, however, participate in virtually every function of the cell city — in other words, they are the bricks and lumber, messengers, copy machines, waste recyclers and more. Every cell typically contains hundreds of different kinds of proteins that function together to generate the behavior of the cell. An important part of cell biology is investigation of molecular mechanisms by which proteins are moved to different places inside cells or secreted from cells.

    Most proteins are synthesized by ribosomes in the cytoplasm. This process also is known as protein biosynthesis or protein translation. Some proteins, such as those to be incorporated in membranes (membrane proteins) are transported into the endoplasmic reticulum (ER) during synthesis and further processed in the Golgi apparatus. From the Golgi, membrane proteins can move to the plasma membrane or to other subcellular compartments, or they can be secreted from the cell. There is regular movement of proteins through these compartments. ER- and Golgi-resident proteins associate with other proteins but remain in their respective compartments. Other proteins pass through the ER and Golgi to the plasma membrane.

    Most of the genetic information in the cell resides in the nucleus and is contained within the chromosomes (mitochondria also carry some DNA of their own). The study of the microscopically visible stages of cell division during mitosis and meiosis generally is considered part of cell biology, while the actual submicroscopic activity of DNA replication and protein synthesis is considered part of molecular biology.


    Microscopes

    The microscopes we use today are far more complex than those used in the 1600s and 1800s. There are two primary types of modern microscopes used: light microscopes and electron microscopes. Electron microscopes provide higher magnification, higher resolution, and more detail than light microscopes. However, a light microscope is required to study living cells as the method used to prepare the specimen for viewing with an electron microscope kills the specimen.

    Cytotechnologist

    Figure 1. These uterine cervix cells, viewed through a light microscope, were obtained from a Pap smear. Normal cells are on the left. The cells on the right are infected with human papillomavirus (HPV). Notice that the infected cells are larger also, two of these cells each have two nuclei instead of one, the normal number. (credit: modification of work by Ed Uthman, MD scale-bar data from Matt Russell)

    Have you ever heard of a medical test called a Pap smear (shown in Figure 1)? In this test, a doctor takes a small sample of cells from the uterine cervix of a patient and sends it to a medical lab where a cytotechnologist stains the cells and examines them for any changes that could indicate cervical cancer or a microbial infection.

    Cytotechnologists (cyto = “cell”) are professionals who study cells via microscopic examinations and other laboratory tests. They are trained to determine which cellular changes are within normal limits and which are abnormal. Their focus is not limited to cervical cells they study cellular specimens that come from all organs. When they notice abnormalities, they consult a pathologist, who is a medical doctor who can make a clinical diagnosis.

    Cytotechnologists play a vital role in saving people’s lives. When abnormalities are discovered early, a patient’s treatment can begin sooner, which usually increases the chances of a successful outcome.


    Parts and Functions

    The plant cell organelles play an essential role in carrying out the regular activities of the cell. For example, photosynthesis which is a characteristic of the plants is performed in the chloroplast while synthesis of ATP (adenosine triphosphate), a form of energy, takes place in the mitochondria.

    The outermost covering of the plant cell is the protective layer, the cell wall. Its main function includes giving support, maintaining the cell shape, and controlling the growth of the cell.

    Next to the cell wall, lies the cell membrane that comprises a protein and lipid bilayer. Its main function is selective transport of nutrients, wherein some are allowed to enter the cell, while others are restricted.

    Vacuoles are organelles whose shape and structure, alters with respect to the cell requirements. They are filled with a water-like solution that contains enzymes, organic and inorganic molecules.

    The cell nucleus is simply the control center of the plant cell, as it contains hereditary material, along with other essential cell components. Overall, the nucleus is responsible for protein synthesis, cell growth, division, and development.

    Would you like to write for us? Well, we're looking for good writers who want to spread the word. Get in touch with us and we'll talk.

    The portion of the plant cell excluding the nucleus is called cytoplasm, which is filled with jelly-like cytoplasmic fluid and in which the majority of cell organelles are present.

    These are the organelles which perform the function of photosynthesis and storage of starch molecules. Plastids are of different types and contain photosynthetic pigments.

    Mitochondria, also known as powerhouse of the cell, plays the crucial role of generating chemical energy for proper functioning of the plant cell. They are present in many numbers and contain hereditary material.

    Ribosomes are of two types, attached and free. The former is found attached to the endoplasmic reticulum, while the latter is suspended freely in the cytoplasm. Both types of ribosomes are responsible for protein synthesis.

    Golgi bodies are made up of 4-8 stacks (called cisternae), and are useful for packaging macromolecules that are synthesized by the cell. They are also responsible for transportation of nutrients.

    This is the organelle that connects the nucleus and cytoplasm. It performs the function of synthesizing and storing steroids and glycogen. Endoplasmic reticulum with attached ribosomes are called rough endoplasmic reticulum (RER).

    These are microbodies of the plant cells that contain various degradation enzymes. Peroxisomes play the major role of digesting complex fatty acids including aiding in photosynthesis.

    Thus, a plant cell functions smoothly with the help of its various structural components. Though it is eukaryotic like that of animals, it differs significantly from an animal cell. While there may be a few similarities between plant and animal cells, the key distinguishing feature between the two is the presence of a cell wall and chloroplast in plant cells, both of which are absent in animal cells. If viewed under the microscope, one can see large, prominent vacuoles at the center of a plant cell, whereas an animal cell comprises only a small, inconspicuous vacuole.

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    The nucleus is a spherical-shaped organelle present in every eukaryotic cell. It is the control center of eukaryotic cells, responsible for the coordination of genes and gene expression. The structure&hellip

    Plant cells have always spurred curiosity amongst biology students, besides others. Hence, here in this article, I have provided some detailed information.

    We know plants from time immemorial and they are a part of our day-to-day life, either directly or indirectly, but do we actually know what does a plant cell structure&hellip


    Watch the video: Cells - Introduction. Biology. Dont Memorise (December 2022).