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Biochemistry Introduction - Q&A Review
1. What are the chemical elements that form most of living biological matter? The chemical elements that form most of the molecules of living beings are oxygen (O), carbon (C), hydrogen (H) and nitrogen (N). 2. Living beings are made of organic and inorganic substances. According to the complexity of their molecules how can each of those substances be classified? Inorganic substances, like water, mineral salts, molecular oxygen and carbon dioxide, are small molecules made of few atoms. Organic substances, in general, like glucose, fatty acids and proteins, are much more complex molecules made of sequences of carbons bound in carbon chains. The capacity of carbon to form chains is one of the main chemical facts that permitted the emergence of life on the planet. Biochemistry Introduction Review - Image Diversity: carbon chains 3. What are the most important inorganic molecular substances for living beings? The most important inorganic substances for living beings are water, mineral salts, carbon dioxide and molecular oxygen. (There are several other inorganic substances without which cells would die.) 4. What are mineral salts? Where in living beings can mineral salts be found? Mineral salts are simple inorganic substances made of metallic chemical elements, like iron, sodium, potassium, calcium and magnesium, or of non-metallic elements, like chlorine and phosphorus. They can be found in non-solubilized form, as part of structures of the organism, like the calcium in bones. They can also be found solubilized in water, as ions: for example, the sodium and potassium cations within cells. 5. What are the most important organic molecules for living beings? There are many types of organic molecules that are important for the living beings. Especially important are amino acids and proteins, carbohydrates (including glucose), lipids and nucleic acids (DNA and RNA). Biochemistry Introduction Review - Image Diversity: amino acid molecule protein molecule carbohydrate molecule lipid molecule nucleic acid molecule 6. What are the main functions of the organic molecules for living beings? Organic molecules, like proteins, lipids and carbohydrates, perform several functions for living organisms. Noteworthy functions are the structural function (as part of the material that constitutes, delimits and maintains organs, membranes, cell organelles, etc.), the energetic function (chemical reactions of the energetic metabolism), the control and informative function (genetic code control, inter and intracellular signaling, endocrine integration) and the enzymatic function of proteins (facilitation of chemical reactions). 7. What are some examples of the structural function of organic molecules? Organic molecules have a structural function as they are part of cell membranes, cytoskeleton, organ walls and blood vessel walls, bones, cartilages and, in plants, of the conductive and support tissues. 8. What are some examples of the energetic function of organic molecules? Since they are complex molecules, presenting many chemical bonds, organic molecules store large amount of energy. Glucose, for example, is the main energy source for the formation of ATP (adenosine triphosphate), a molecule that is necessary in several metabolic reactions. ATP is an organic molecule too and is itself the energy source for many biochemical reactions. Fat, proteins and some types of organic polymers, like starch and glycogen, that are polymers of glucose, are energy reservoirs for the organism. 9. What are some examples of the control and informative function of organic molecules? Based on genetic information, organic molecules control the entire work of the cell. The nucleic acids, DNA and RNA, are organic molecules that direct the protein synthesis, and proteins in their turn are the main molecules responsible for the diversity of cellular biological tasks. In membranes and within the cell, some organic molecules act as information receptors and signalers. Proteins and lipids have an important role in the communication between cells and tissues, acting as hormones, substances that transmit information at a distance throughout the organism. 10. What are biopolymers? Polymers are macromolecules made by the union of several smaller identical molecules, called monomers. Biopolymers are polymers present in the living beings. Cellulose, starch and glycogen, for example, are polymers of glucose. |