Chemistry Of Life PDF

Chapter 2 CHEMISTRY OF LIFE Chemistry is the study of atom and element.  Objective By the end of this section, you will be able to: Describe matter and elements D...

Chapter 2 CHEMISTRY OF LIFE Chemistry is the study of atom and element.  Objective By the end of this section, you will be able to: Describe matter and elements Describe the interrelationship between protons, neutrons, and electrons, and the ways in which electrons can be donated or shared between atoms Presentation title 2  The Building Blocks of Molecules life is made up of matter. All matter is composed of elements, substances that cannot be broken down or transformed chemically into other substances. Each element is made of atoms. A total of 118 elements have been defined only 92 occur naturally, and fewer than 30 are found in living cells 26 elements are unstable and, therefore, do not exist for very long or are theoretical and have yet to be detected. Presentation title 3  = Molecule Presentation title 4  Atoms electron= proton > neutron. Atom is the smallest component of an element that retains all of the chemical properties of that element. Presentation title 6  Chemical Bonds Why form chemical bonds? The basic answer is that atoms are trying to reach the most stable (lowest-energy) state that they can. There are four types of bonds or interactions: ionic covalent hydrogen bonds van der Waals interactions When an atom does not contain equal numbers of protons and electrons, it is called an ion. Positive ions are formed by losing electrons and are called cations. catch eletrone(+) Negative ions are formed by gaining electrons and are called anions. catch protone (-) Presentation title 7  Ex: Elements tend to fill their outermost shells with electrons. To do this, they can either donate or accept electrons from other element. Presentation title 8  Ionic Bonds Ionic bonds are bonds formed between ions with opposite charges. Transfer of an electron, so one atom gains an electron while one atom loses an electron. One of the resulting ions carries a negative charge (anion), and the other ion carries a positive charge (cation). Because opposite charges attract, the atoms bond together to form a molecule. Presentation title lack of electrone more electrone 9  in this case which one and low electron must give to another to complete: Na have 1 lack 7 cl have 7 lack 1 Presentation titleso Na give 1 to Cl to complete. 10  Covalent Bonds Electron is shared between two elements and are the strongest and most common form of chemical bond in living organisms. 2 type of covalent bond: Polar and Non polar Presentation title 11  Covalent Bonds In a polar covalent bond, the electrons are unequally shared by the atoms and spend more time close to one atom than the other. Presentation title 12  Covalent Bonds Nonpolar covalent bonds: form between two atoms of the same element, or between atoms of different elements that share electrons more or less equally. Ex 1: nonpolar covalent bond is found in methane (CH4) Ex 2: (O2) is nonpolar because the electrons are equally shared between the two oxygen atoms Presentation title 13  Hydrogen Bonds Hydrogen atom is slightly positive (δ+), it will be attracted to neighboring negative partial charges (δ–). When this happens, a weak interaction occurs between the δ+ charge of the hydrogen atom of one molecule and the δ– charge of the other molecule. This interaction is called a hydrogen bond. Individual hydrogen bonds are weak and easily broken, but many hydrogen bonds together can be very strong. Presentation title 14  Van der Waals Interactions Weak attractions or interactions between molecules They occur between polar, covalently bound, atoms in different molecules Presentation title 15  2.2 Water Water is essential to life. Approximately 60 to 70 percent of our body is made up of water. Without water, life simply would not exist. Water Is Polar Water Stabilizes Temperature Water Is an Excellent Solvent Presentation title Water Is Cohesive 16  Water Is Polar The hydrogen and oxygen atoms within water molecule form polar covalent bonds. The shared electrons spend more time associated with the oxygen atom then they do with hydrogen atom. Water molecule also attract other polar molecule and form hydrogen bonds (sugar). When a substance readily forms hydrogen bonds with water, it can dissolve in water and it is hydrophilic (water-loving). Hydrogen bonds are not readily formed with nonpolar substances like oils and fat, it can not dissolve in water and it is referred to hydrophilic (water fearing). 17 Presentation title  Water Stabilizes Temperature Hydrogen bonds in water allow it to absorb and release heat energy more slowly than many other substances. Temperature is a measure of the motion of molecules. The increase in motion, the increase in energy and giving the rise in temperature. Because hydrogen bonds can be create and disrupted rapidly, water absorbs and increase in energy and change temperature only minimally. Specifically in order for water to increase in temperature hydrogen bonds must break. 18  Water Is an Excellent Solvent Because water is polar with slight positive and negative charge, ionic compounds and polar molecules can readily dissolve in it. The charge particle will form hydrogen bonds with a surrounding layer of water molecules. Example : NaCl molecules, the sodium and chloride ion is separate, or dissociate in the water and spheres of hydration formed around the ions. 19  Water Is Cohesive Cohesion is an attraction between molecules of the same substance. Because water is polar molecule. It can attracted to itself. A single water molecule maybe involved in as many as four hydrogen bonds at the same time. It stick together until its hydrogen bonds are broken. 20  2.3 Biological Molecules There are four major classes of biological macromolecules Proteins Nucleic acid Lipids Carbohydrates 21 Presentation title 22  prefer water oil not full oil full don't prefer water Presentation title 23 Presentation title 24  2.3 Biological Molecules Each is an important component of the cell and performs a wide array of functions. Combined, these molecules make up the majority of a cell’s mass. Biological macromolecules are organic, meaning that they contain carbon. In addition, they may contain hydrogen, oxygen, nitrogen, phosphorus, sulfur, and additional minor elements. 25  Carbon Bonding Carbon contains four electrons in its outer shell The simplest organic carbon molecule is methane (CH4). Carbon atoms can also bond to carbon atoms. (a) This molecule of stearic acid has a long chain of carbon atoms. (b) Glycine, a component of proteins, contains carbon, nitrogen, oxygen, and hydrogen atoms. (c) Glucose, a sugar, has a ring of carbon atoms and one oxygen atom.. 26  Carbohydrates Carbohydrates can be represented by the formula (CH2O)n, where n is the number of carbon atoms in the molecule. The ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules. Carbohydrates are classified into three subtypes: Monosaccharides Disaccharides Polysaccharides 27  Monosaccharides (mono- = “one”; sacchar- = “sweet”) are simple sugars. The most common of which is glucose the number of carbon atoms usually ranges from three to six. Most monosaccharide names end with the suffix -ose. Depending on the number of carbon atoms in the sugar, they may be known as trioses (three carbon atoms), pentoses (five carbon atoms), and hexoses (six carbon atoms). Monosaccharides may exist as a linear chain or as ring-shaped molecules In aqueous solutions, they are usually found in the ring form. 28  Monosaccharides Glucose, galactose, and fructose are isomeric monosaccharides, meaning that they have the same chemical formula but slightly different structures. 29  Disaccharides (di- = “two”) form when two monosaccharides undergo a dehydration reaction (a reaction in which the removal of a water molecule occurs). During this process, the hydroxyl group (-OH) or one monosaccharide with a hydrogen atom of other monosaccharide, releasing a molecule of water (H2O) and forming a covalent bond between atoms in the two sugar molecule. 30  Polysaccharide A long chain of monosaccharides linked by covalent bonds is known as a polysaccharide (poly- = “many”). Starch, glycogen and cellulose are examples of polysaccharide. Starch is the stored form of sugars in plants and is made up of amylose and amylopectin (both polymers of glucose). 31  Polysaccharide Glycogen is the storage form of glucose in humans and other vertebrates, and is made up of monomers of glucose. Glycogen is the animal equivalent of starch and is a highly branched molecule usually stored in liver and muscle cells. Whenever glucose levels decrease, glycogen is broken down to release glucose. 32  Polysaccharide Cellulose is one of the most abundant natural biopolymers. The cell walls of plants are mostly made of cellulose, which provides structural support to the cell. Wood and paper are mostly cellulosic in nature. Cellulose is made up of glucose monomers that are linked by bonds between particular carbon atoms in the glucose molecule. 33 Carbohydrates 34  Lipids Lipids are hydrophobic (“water fearing”), or insoluble in water, because they are nonpolar molecules. Lipids include fats, oils, waxes, phospholipids, and steroids. Lipid Food 35  Fatty acids Have a long chain of hydrocarbons to which an acidic carboxyl group is attached, hence the name “fatty acid.” The number of carbons in the fatty acid may range from 4 to 36; most common are those containing 12–18 carbons. In a fat molecule, a fatty acid is attached to each of the three oxygen atoms in the –OH groups of the glycerol molecule with a covalent bond 36 Fatty acids 37 38  Protein The functions of proteins are very diverse because there are 20 different chemically distinct amino acids that form long chains, and the amino acids can be in any order. Amino acids are the monomers that make up proteins. Each amino acid has the same fundamental structure, which consists of a central carbon atom bonded to an amino group (–NH2), a carboxyl group (– COOH), and a hydrogen atom. 39 40 Presentation title 41  Nucleic acids Nucleic acids are key macromolecules in the continuity of life. The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). 42 “ Any Question ”