5.2 Lipids 5.21 Triglycerides 5.22 Phospholipids 5.23 Wax 5.24 Steroids. 5.3 Proteins 5.4 Nucleic Acids

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1 BIOCHEMISTRY Class Notes Summary Table of Contents 1.0 Inorganic and Organic Compounds 2.0 Monomers and Polymers 3.0 Dehydration (Condensation) Synthesis 4.0 Hydrolysis Reaction 5.0 Organic Compounds 5.1 Carbohydrates 5.11 Monosaccharides 5.12 Dissacharides 5.13 Polysaccharides 5.2 Lipids 5.21 Triglycerides 5.22 Phospholipids 5.23 Wax 5.24 Steroids 5.3 Proteins 5.4 Nucleic Acids 1.0 Inorganic and organic compounds. In chemistry there are inorganic and organic compounds. Inorganic compounds are not made from and do not come from living organisms. Organic compounds make up or come from living organisms. For example, a rock is an inorganic compound composed of inorganic elements. Whereas, a piece of wood is made of organic compounds because there piece of wood once came from a live tree. All organic compounds must contain carbon, hydrogen and oxygen. Some organic compounds such as proteins and nucleic acid also contain nitrogen. The we are covering now state in order to understand the concept that the fundamental life processes of plants and animals depend on a variety of chemical reactions that occur in specialized areas of the organisms cells, students must know that most macromolecules (carbohydrates, lipids, proteins and nucleic acids) in cells and organisms are synthesized from a small collection of simple precursors. Basically what this standard is stating is that large molecules (polymers, or macromolecules) are composed of small molecules called monomers. 2.0 Monomers and Polymers A monomer is made of one subunit. A polymer is made of 3 or more monomers. Monomers and polymers are made and broken down by two chemical reactions, dehydration (condensation) and hydrolysis.

2 3.0 Dehydration (Condensation) Synthesis Polymers are formed by condensation (dehydration) reactions. This type of reaction can be recognized because water is formed as a product. Dehydration reaction build large molecules (macromolecules or polymers) from small molecules (precursors or monomers). Figure 1: Condensation ( Dehydration) Reaction During dehydration water is formed by the removal of a hydrogen from one monomer and the removal of a hydroxyl (-OH) from another monomer. The hydrogen and hydroxyl bonds together to form water H2O. For every two monomers joined 1 water is produced. So if 6 monomers are joined to form 1 polymer, 5 waters are produced. 4.0 Hydrolysis Reaction Macromolecules or polymers are broken down into precursors or monomers by hydrolysis reaction. This type of reaction uses water to split large molecules into small molecules - polymers into monomers. Figure 2: Hydrolysis Reaction Hydrolysis split polymers or macromolecules by inserting a hydrogen on one monomer and a hydroxyl (-OH) on another. 5.0 Organic Compounds All living organisms are made of organic compounds. There are four types of organic compounds; carbohydrates, lipids, proteins, and nucleic acids. All organic compounds contain carbon - C, hydrogen - H, and oxygen - O. Proteins and nucleic acids also have nitrogen - N. Carbohydrates provide a quick sources of energy. Lipids can be used to store energy, water proofing and are found in hormones. Proteins provides the building materials for growth and repair. Nucleic acids store genetic information. 5.1 Carbohydrates Carbohydrates are sugars and not all of them are sweet. Carbohydrates provide a quick source of energy. In carbohydrates the ration of hydrogen to oxygen is two to one, 2:1. Meaning for every oxygen there are two hydrogen. Carbohydrates are divided into three groups; monosaccharides, disaccharides and polysaccharides. The prefix and roots of the words give you a clue to their meaning. Mono = one, di = two and poly three or more. Saccharide = sugar. So monosaccharide are made of one sugar molecule, disaccharides are made of two sugar molecules and poly saccharides are made of many (in the hundreds) sugar molecules.

3 5.11 Monosaccharides A monosaccharide is a simple six carbon sugar molecules. There are three types of monosaccharides, glucose, fructose, and galactose. They all have the same chemical or molecular formula C6H12O 6. Monosaccharides are isomers, meaning they have the same chemical formula but different structural formula. In the structural formula of monosaccharides the atoms are arranged differently giving each monosaccharide its own unique properties. glucose fructose galactose Glucose is the main source of energy for plants and animals. All provide energy but glucose gives the most energy. Glucose is produced by green plants during photosynthesis. Fructose the sweetest of all monosaccharides is found in fruits. Galactose is found in milk and milk products such as cheese. Monosaccharides are the precursors for all other carbohydrates Disaccharides Disaccharides are formed by dehydration (condensation) reaction. Remember dehydration removes a hydrogen and a hydroxyl (-OH) to form water as a by-product. monosaccharide monomer + monosaccharide monomer C12H24O12 - H2O Condensation forms water from monomers C H O + H O Disaccharides all have the same chemical or molecular formula, C12H22O 11. There are three types of disaccharides; sucrose, lactose and maltose. Sucrose is table sugars produces from sugar cane or sugar beet. Sucrose is formed from glucose plus fructose. Lactose is found in milk and milk products. Lactose is formed from glucose plus galactose. Maltose is a grain sugar found in grains, such as wheat and barley, and grass. Maltose is formed from two molecules of glucose. Notice that all disaccharides contain glucose. Disaccharides are broken down into their precursors (monosaccharide) by hydrolysis reaction. One water molecule is with the help of an enzyme gives one hydrogen to one monosaccharide and a hydroxide to the other monosaccharide so water is used to split the disaccharide into two monosaccharides.

4 5.13 Polysaccharides Polysaccharides are many monosaccharides linked together to form very long chains. Since the molecular formula is very complex, you are not required to know them. Polysaccharides are also formed by dehydration reaction. Remember for every monosaccharide that is linked to another monosaccharide one water is formed. So if 5 monosaccharides are linked together 4 water molecules are produced. If 50 monosaccharides are linked together 49 water molecules are produced. If 200 monosaccharides are linked together 199 water molecules are produced. Get the picture, for the total number of monosaccharides linked substrate one from the total to get the number of water produced. So if you are given a problem to calculate the chemical formula of a polysaccharide to the following: add the chemical formulas together and subtract the total number of water to get the chemical formula of a polysaccharide. For example: A polysaccharide is formed from 11 molecules of monosaccharides, calculate the chemical formula of the polysaccharide. monosaccharide monomers + C66H132O66 - H O subtract out 10H O (to subtract change it to H O C H O The chemical formula is C66H112O56 Polysaccharides are broken down into monosaccharides by hydrolysis reaction. Water is used with the help of an enzyme to split the polysaccharide into its monosaccharide precursors. You can figure out

5 how many water molecules are need to split a polysaccharide. For example. Using the above chemical formula of a polysaccharide, C H O - the chemical formula of a monosaccharide is - divide the 6 from carbon of the monosaccharide into the 66 carbon of the polysaccharide and you get 11 - so the polysaccharide was made from 11 monosaccharides - subtract 1 from 11 and you get the number of water molecules needed to split C66H112O 56 into its monosaccharide precursors water molecules are needed There are three types of polysaccharides; starch, cellulose, and glycogen. Starch is produced by plants to store energy. There are two forms of starch one is a highly branched carbon chain and the other is a long unbranched carbon chain. Examples of plants the produce starch are potatoes, rice, and corn. Cellulose is also produced by plants. Cellulose gives plant strength, support and rigidity. Remember plants don t have skeletons. Cellulose enables a plant to stand upright. Cellulose are long straight chains of carbon. Note, humans can not digest cellulose. To do so we would need an extra stomach and special bacteria like cows. But cellulose is good for human because it acts as roughage to clean out the intestines like a scrub brush. The crunchy sound you hear in fruit or vegetables is the sound of cellulose breaking. Glycogen is found only in animal and is also used to store energy. Glycogen is a high branched chain of carbons. Its is store between the muscle cells. The liver can break down glycogen to provide energy. However if an animal ever reach this point it must be starving and out of fat reserves. 5.2 Lipids Lipids are organic molecules that store large amounts of energy. Lipids can provide up to 4 times the amount of energy as a carbohydrate, but they take longer to breakdown. A special property of lipid is they are insoluble in water, meaning they do not dissolve in water. There are four types of lipids; triglycerides, phospholipids, wax, and steroids Triglycerides Triglycerides are made of 3 fatty acid tails attached to a glycerol head. The fatty acid tails are long chains of carbon and hydrogen with a carboxyl group (-COOH) at one end. The fatty acid tails are hydrophobic. Hydro = water and phobic = fear, so hydrophobic literally means fear of water. Hydrophobic molecules are not attracted to water so they are non polar. The glycerol head is a short three carbon molecule with one hydroxyl group (-OH) per carbon. It is the fatty acid tails that make triglycerides insoluble in water. There are two types of triglycerides; oil and fat. Oil is a liquid at room temperature and is produced by plants. Fat is a solid at room temperature and is produced by animals. You may be familiar with the terms saturated fat and unsaturated fat. Saturated fat is a fatty acid molecule saturated with hydrogen. The

6 hydrogen forms single bonds with the carbon forming straight chains. Saturated fatty acids of fats can nestle closely together, forming solid lumps at room temperature. Unsaturated fatty acids have double bonds between the carbons so few hydrogens can bond. Oils have mostly unsaturated fatty acids. The double bond in the unsaturated fatty acid produces kinks in the fatty acid chains. The kinks keep the oil molecules apart so oil is a liquid at room temperature. Oils can be converted to a fat by breaking the double bonds between carbons and replacing them with single bonds and adding hydrogens. This type of oil is called hydrogenated oil and is used to make margarine. Saturated fats can be used by the body to make cholesterol. Cholesterol comes in two forms bad cholesterol which cause plaque in the arteries, and good cholesterol which is needed for proper cellular functions. So people who must keep control of the cholesterol levels should avoid foods with saturated fats Phospholipids There is another type of lipid called phospholipids. Phospholipids are similar to fats or oils except that only two fatty acid tails are attached to the glycerol backbone. The third position on the glycerol is occupied by a polar head composed of phosphate group (-PO 4) which is usually attached to a nitrogen containing functional group. The phosphate group is negatively charged and the nitrogen containing group is positively charged. The glycerol head with its phosphate is polar and hydrophilic. Philic means to love, so hydrophilic literally means water loving. The fatty acid tails are non polar and hydrophobic. Hydro = water and phobic = fear, so hydrophobic literally means fear of water. Hydrophobic molecules are not attracted to water and hydrophilic molecules are attracted to water. This gives phospholipids it unique reaction in water that is important in cell membrane function Wax Wax are chemically similar to fats. They are very saturated, making them solid at normal outdoor temperatures. Wax is made of 2 fatty acid tails attached to an alcohol chain. Again the fatty acid tails make them insoluble in water. The main function of wax is waterproofing and forming protective layers. Wax is found on the leaves and stems of plants, in mammal fur and ears, and on an insects exoskeleton.

7 5.24 Steroids Steroids are made of 4 carbon rings attached to different functional groups. This makes them look chemically different from other lipids. Steroids are classified as lipids because they are insoluble in water. Remember insoluble means it will not dissolve in water. Cholesterol, testosterone, and estrogen are examples of steroids. Steroids are found in hormones, nerve tissue and poisons. 5.3 Proteins Proteins provide the structural materials for growth and repair. Proteins are macromolecules made of amino acids. There are 22 different kinds of amino acids. An amino acid is made of 3 components: a carboxyl group (COOH), an amine group (NH ) and a R-group. 3 The R-group is a variable group, meaning it varies or is different for each type of amino acid. It is the R-group that gives each amino acid its distinctive properties. Depending of the R-group some amino acids are hydrophilic and polar so are soluble in water and others are hydrophobic with non polar R-groups making them insoluble in water. Amino acids with sulfur in its R-group (cysteine) can bond with other amino acid that have a cysteine R-group linking two proteins together. This bonds are called disulfide bridges. The linked proteins will bend at each disulfide bridge. A visual example of disulfide bridges is hair. Straight hair have few disulfide bridges. Naturally curly hair has many disulfide bridges. When a person gets a perm to make their hair curly, them are chemically causing disulfide bridges to form. If a person has a perm to make curly hair straight, they are breaking the natural disulfide bridges. Proteins have many functions such as: providing structural materials for growth and repair, function in movement because muscle are made of protein structures called actin and myosin, proteins function in defense via antibodies in blood, proteins store glycogen in mammal, and finally proteins can act as enzymes which speed up or start chemical reactions. The amino acids of proteins are joined by the nitrogen in the amino group bonding to the carbon in the carboxyl group of another amino acid. These bonds are called peptide bond. Joined amino acids are also called peptide. So peptide is another word for protein. Dipeptide is two amino acids joined. Polypeptide is a long chain of amino acids joined together.

8 Proteins are highly organized molecules that can have up to four levels of structure. The primary structure is the sequence of amino acid that make up the protein. This is the first structure that is coded and produced from DNA. In the secondary structure hydrogen bonds causes the protein molecules to form a helix (like a coiled spring). Example are hair, subunits of hemoglobin. In the tertiary structure proteins can assume complex 3- dimensional shapes. Basically the secondary structure has folded on itself. The quaternary structure is the grouping (aggregation) of 2 or more tertiary structures. To understand the structures of a protein try this: take a piece of bendable wire, when the wire is straight it represents the primary structure. Now twist the wire around a pencil and slide it off when done, you have the secondary structure. Take the secondary structure and fold it into a ball creating the tertiary structure. If you have different colors of wire, the quaternary structure would be the combining of different color of tertiary structures. The exact type, position, and number of amino acids bearing specific R-groups determines the 3-dimensional shape of the protein which in turn determines its biological function. 5.4 Nucleic Acids Nucleic acids store and carries genetic information for cellular structures and functions. Nucleic acids are made of nucleotides. There are two types of nucleic acids, DNA and RNA. DNA stands for deoxyribose nucleic acid and RNA stands for ribose nucleic acid. We will learn more about nucleic acids later. End of Summary