Cell lec 2 - QUIZ 1 Your friend has just returned from a...

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QUIZ 1 Your friend has just returned from a deep sea mission and claims to have found a new single-celled life form. He believes this new life form may not have descended from the common ancestor that all types of life on Earth share. However, he’s never taken Cell Biology, so he asks you determine whether his claim is true. In order to verify or dispute your friend’s claim, you realize that you must first make a list of characteristics common to all prokaryotes and eukaryotes, so that you can check whether this new life form is similar or different from all other types of life on Earth. Name two basic characteristics that you could check to distinguish all prokaryotes and eukaryotes from newly derived life forms.
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PROTEIN A Protein molecule is made from a long chain of 20 different types of amino acids, each linked to its neighbor through a covalent bond. Proteins constitute the major component of an actively growing cell. Although proteins are not the main building material of cell, they also regulate almost all its activities. Most biological processes would not occur under the conditions of temperature, pressure, pH, etc. found in cells if not for the existence of enzymes to catalyze the reactions involved.
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Proteins embedded in the plasma membrane, form channels and pumps that control the passage of small molecules into and out of the cell. Some proteins carry messages form one cell to an other, while others act as signer integrators that relay sets of signals from the plasma membrane to the nucleus of individual cells.
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PROTEIN Proteins are without a doubt the most important and ubiquitous macromolecules in the cell. Almost all enzymes are proteins, and proteins form the basis of most cellular structures. Connective tissue, muscle fibrils, cilia, flagella- all are made primarily or exclusively of proteins. Based on function, proteins fall into four major classes. 1 . Many proteins are enzymes , serving as catalysts which the life depends on, e.g. tryptophan synthetase used to make amino acid tryptophan; pepsin degrades dietary proteins in the stomach.
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2 . Structural proteins , provide support and shape to cells and organelles, giving cells their characteristics appearances, e.g. collagen and elastin are common constituents of extracellular matrix and form fibers in tendons and ligaments. 3. Motility proteins , play key roles in the contraction and movement of cells and intracellular structures, e.g. myosin in skeletal muscle cells provide the motive force for animals to move.
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4. Regulatory proteins , are responsible for and coordination of cellular functions, ensuring that cellular activities are regulated to meet cellular needs, e.g. bind to DNA to switch genes on or off. Lactose repressor in bacteria silences the gene for the enzymes that degrade the sugar lactose. Most proteins are
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This note was uploaded on 05/30/2011 for the course BIOLOGY 3042 taught by Professor Lekanlatinwo during the Fall '10 term at Florida A&M.

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Cell lec 2 - QUIZ 1 Your friend has just returned from a...

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