Cells IntroductionCells can be described as the smallest unit of a being that performs a particular function. Cells are the basic building blocks of living organisms. Nucleic acids, proteins,carbohydrates and lipids are the organic molecules that make up the cell.
Prokaryotes vs EukaryotesThere are two types cells prokaryotes, with their cytoplasmic genomes, and eukaryotes, with their nuclear-encased genomes and other membrane-bound organelles. Eukaryotes can be defined as cells that contain a nucleus and other organelles bound within membranes. Prokaryotes can be defined as cells with no nuclear membrane, no organelles in the cytoplasm except ribosomes, and has its DNA in the form of single continuous strands that make coils. Cells are found in many shapes and sizes even though they are small. Cells that perform similar functions together form tissues which together form organs that then form organisms. In that way we are composed entirely of cells. Every component of our body whether it is the skin which is composed of skin cells or our liver which is composed of liver cells adds up to make 10 trillion cells that help us perform all our life processes. In conclusion humans=magic.
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Cells can exist in multicellular or unicellular organisms. A multi cellular organism is organism consisting of numerous amount of cells where as a unicellular organism only consists of one cell. In a unicellular organism a single cell carries out all the life processes whereas in a multicellular organism there are specialized cells to carry out particular functions. Specialized cells vary in size, shape and function as they are structurally modified to cater to the complex structures of multicellular organisms. They help the cells to have certain tissues develop which are critical for function of the cell and to respond to the environment.
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Cell TheoryIn 1665 Robert Hooke examined thin sections of a bottle cork under a crude microscope. He found hexagonal chambers packed together like a honeycomb. This was a crucial discovery that led people to wonder about what we are made of and led to the discovery of the cell theory. In 1674 Anton van Leeuwenhoek a Dutch tailor examined clothing under a microscope and discovered bacteria that he referred to as 'animacules'. In 1838 the German Botanist Matthias Schleiden discovered that all plants were composed of cells. Then a German zoologist, Theodor Schwann, discovered that all animals were composed of cells in 1939. 6 years prior to that German physician named Rudolph Virchow was doing experiments with diseases when he found that all cells come from other existing cells. This marks the events that created the cell theory. According to the cell theory
1. All living things are made up of cells. 2. Cells are the basic units of structure and function in living things. 3. Living cells come only from other living cells. |
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What is an organelle?Organelles are miniature structures that carry out certain tasks in the cell. These organelles are contained within the cytoplasm. Every organelle within the cell performs a function that is necessary for function of the cell. The types of organelles and their locations will be further discussed when I will talk about Plant and Animal cells and their organelles on the next webpage.
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