BiologicalMolecules211

BiologicalMolecules211 - Biological Molecules 1 The...

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Biological Molecules - 1 The majority of the molecules found in living organisms are based on the element, carbon, along with nitrogen, oxygen and hydrogen. The specific chemical properties of these molecules are, to a large extent, determined by the functional groups attached to carbon backbones. Many of our biological molecules are large, often comprised of thousands of atoms, and are assembled from smaller molecules that are either identical to each other, or similar to each other. These large molecules are called macromolecules or polymers. The "building blocks" of these polymers are called monomers or subunits. We obtain great diversity of polymers from just a few small monomers, by varying number, sequence and bonding arrangements. Polymers are formed by condensation reactions and broken down by hydrolysis reactions. (See Carbon Chemistry) Our biological molecules are grouped into four categories: carbohydrates, lipids, proteins and nucleic acids. All but lipids are polymers. These molecules perform the functions of our cells: structural support, protection, transport, energy and energy storage, defense, regulation, motility and information storage. The functions of our macromolecules are related to their shape and the chemical properties of the monomers from which they are constructed.
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Amino Acids and Proteins Proteins are polymers composed of combinations of 20 different amino acids. Proteins range in size from about 50 to well over 4000 amino acids and vary in the number and proportions of the different amino acids. A single cell may have 10,000 or more different proteins. This diversity of proteins is essential for the functioning of each cell in a living organism. About half of the non-water component of a typical cell is protein. Protein Functions ( Details later ) Enzymes Globular proteins that catalyze the chemical reactions that occur in cells. We will discuss enzyme function during our section on metabolism. Structural/Support Proteins (fibrous proteins) Connective tissue in animals (collagen – the most abundant vertebrate protein) Webs, cocoons and other arthropod structures Hair, nails horns, etc. (keratin) Fibrins used in blood clotting Storage Proteins (specialized) Examples are milk casein, ferritin (iron), calmodulin (calcium) and albumin Transport Proteins Plasma membrane proteins carry substances through membranes Oxygen carrier in circulation (hemoglobin) Mineral protein carriers (iron, zinc) Energy transfer molecules Cytochromes Regulatory Proteins Hormones Gene Regulators – transcription factors Osmotic regulation Contractile and Motor Proteins – locomotion and movement Muscle Cilia and flagella, Microtubules, microfilaments and intermediate filaments Receptor Proteins Membrane surface receptor proteins Signal transduction proteins Recognition Proteins Glycoproteins (carbohydrate-protein hybrids) for identification of "self". Defense Proteins
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BiologicalMolecules211 - Biological Molecules 1 The...

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