Understanding Biomolecules: Atoms, Bonds, Water, Carbs, Lipids, Proteins, & Nucleic Acids, Slides of Biology

Download Understanding Biomolecules: Atoms, Bonds, Water, Carbs, Lipids, Proteins, & Nucleic Acids and more Slides Biology in PDF only on Docsity! Biomolecules Docsity.com Atoms • Atoms have 3 components: protons, neutrons, and electrons – The type of element (carbon, iron, etc. ) is entirely determined by how many protons are in the nucleus. • protons and neutrons are in the nucleus – Protons have a +1 charge – Neutrons have no charge • Electrons circle around the nucleus, in a series of shells. – Electrons have a -1 charge – Chemical bonds are created by movements of the electrons between atoms • The number of protons determines which element the atom is. – Hydrogen: 1 proton, carbon = 6 protons, oxygen = 8 protons. – Biological and chemical processes never change the number of protons in any atom. • Normally, the number of electrons is equal to the number of protons, so the atom has no electrical charge: it is neutral. Docsity.com Water • Water forms many hydrogen bonds with other water molecules and with other polar substances. This causes water molecules to stick together (causing surface tension) and stick to other things (causing capillary action, how water gets from the roots to the top of trees). • Polar substances dissolve in water, because water forms hydrogen bonds with the polar molecules. Thus, polar substances are called hydrophilic, or “water-loving”. • Non-polar substances don’t dissolve in water because they can’t form hydrogen bonds, so they are called hydrophobic, or ‘water-fearing”. Oils and fats are examples of non-polar substances. • Soap works by having a non-polar end, which dissolves in grease, and a polar end, which dissolves in water. Soap causes tiny droplets of grease to be suspended in water, where they can be rinsed away. Docsity.com Organic Compounds • It used to be thought that only living things could synthesize the complicated carbon compounds found in cells • German chemists in the 1800’s learned how to do this in the lab, showing that “organic” compounds can be created by non-organic means. – Raw materials: coal and oil • Organic compounds are those that contain carbon. (with a few exceptions such as carbon dioxide and diamonds) Docsity.com Four Basic Types of Macromolecule • Most organic molecules in the cell are long chains of similar subunits. Because they are large, these molecules are called macromolecules. Each macromolecule has a different type of subunit. • The four types of macromolecule are: 1. carbohydrates (sugars and starches), Subunit = simple sugar. 2. lipids (fats). Subunits = fatty acids and glycerol 3. proteins, Subunits = amino acids 4. nucleic acids (DNA and RNA). Subunits = nucleotides • The cell also contains water, inorganic salts and ions, and other small organic molecules. • Plants often produce secondary metabolites: special compounds that attract pollinators, inhibit microorganisms, deter grazing animals, etc. We have found uses for many of these secondary metabolites as medicines, spices, and drugs. Docsity.com Complex Carbohydrates • = polysaccharides (many sugars linked together). – Can be linear chains or branched. • Some polysaccharides are used for food storage: starch. – Starch is a glucose polymer, we have enzymes that easily digest starch. – Starch is a convenient way to store glucose in both plants and animals. • Some polysaccharides are structural: the cellulose of plant cell walls and fibers is a polysaccharide composed of many glucose molecules, but linked together differently than starch. – We don’t have enzymes that can digest these polymers. Cows and termites depend on bacteria in their guts to digest cellulose, producing methane as a byproduct. Docsity.com Lipids • Lipids are the main non-polar component (hydrophobic) of cells. Mostly hydrocarbons— carbon and hydrogen. • They are used primarily as energy storage and cell membranes. • 4 main types: fats (energy storage), phospholipids (cell membranes), waxes (waterproofing), and steroids (hormones). • Waxes: waterproof coating on plants and animals. Composed of fatty acids attached to long chain alcohols. – The ability of plant to coat themselves in waxes was crucial to the ability to live on dry land. • Steroids have carbon atoms arranged in a set of 4 linked rings. – Cholesterol is steroid; it is an essential component of cell membranes (along with the phospholipids). – Many human hormones are steroids Docsity.com Triglycerides and Phospholipids • Triglycerides are the main type of fat. A triglyceride is composed of 3 fatty acids attached to a molecule of glycerol. – Fatty acids are long hydrocarbon chains with an acid group at one end. • Fats store about twice as much energy per weight as carbohydrates like starch. • Phospholipids are the main component of cell membranes. – they have a glycerol with 2 fatty acids attached, plus a phosphate-containing “head” group instead of a third fatty acid. • The head group is hydrophilic, while the fatty acids are hydrophobic. • Cell membranes are 2 layers, with the head groups facing out and the fatty acids forming the interior of the membrane. Docsity.com Protein Structure • A polypeptide is one linear chain of amino acids. A protein consists of one or more polypeptides, and they sometimes contain small helper molecules such as heme. – Many co-factors are vitamins: molecules our body can’t make for itself, so we have to get from our food. • After the polypeptides are synthesized by the cell, they spontaneously fold up into a characteristic conformation which allows them to be active. The proper shape is essential for active proteins. For most proteins, the amino acids sequence itself is all that is needed to get proper folding. – The joining of polypeptide subunits into a single protein also happens spontaneously, for the same reasons. • Denaturation is the destruction of the 3- dimensional shape of the protein. This inactivates the protein, and makes it easier to destroy. Heat is the easiest way to denature proteins: this is the effect of cooking foods. Docsity.com Nucleic Acids • Nucleotides are the subunits of nucleic acids. • Nucleic acids store and transmit genetic information in the cell. • The two types of nucleic acid are RNA (ribonucleic acid) and DNA (deoxyribonucleic acid). • Each nucleotide has 3 parts: a sugar, a phosphate, and a base. • The sugar, ribose in RNA and deoxyribose in DNA, contain 5 carbons. They differ only in that an –OH group in ribose is replaced by a –H in DNA. • The main energy-carrying molecule in the cell is ATP. ATP is an RNA nucleotide with 3 phosphate groups attached to it in a chain. The energy is stored because the phosphates each have a negative charge. These charges repel each other, but they are forced to stay together by the covalent bonds. Docsity.com DNA and RNA • DNA uses 4 different bases: adenine (A), guanine (G), thymine (T), and cytosine (C). The order of these bases in a chain of DNA determines the genetic information. • DNA consists of 2 complementary chains twisted into a double helix and held together by hydrogen bonds. DNA is a stable molecule which can survive thousands of years under proper conditions – The DNA bases pair with each other: A with T, and G with C. • RNA consists of a single chain that also uses 4 bases: however, the thymine in DNA is replaced by uracil (U) in RNA. RNA is much less stable than DNA: it is used to convey information for immediate use by the cell. Docsity.com