Biomolecules The Building Blocks of Life

Transcription

1 Biomolecules The Building Blocks of Life What You ll Learn The four major families of biological macromolecules The functions of each group of biological macromolecules An Organic Compound is a compound that contains carbon. An Enzyme is a protein that helps start or speeds up a chemical reaction. Proteins are a kind of nutrient with a complex molecular structure made up of one or more chains of amino acids. A Carbohydrate is a nutrient molecule made up of carbon, hydrogen and oxygen in a 1:2:1 ratio. Carbohydrates include sugars and starches. A Lipid is an energy dense nutrient. It is made up of carbon and hydrogen. Glucose is a simple sugar that cells use for energy. Amino Acids are the building blocks of proteins. Fatty Acids and Glycerol are the two building blocks of lipids Organic Chemistry Almost all biological molecules contain the element carbon. For this reason, all life is considered carbonbased. Organic chemistry is the study of organic compounds the compounds that contain carbon. A carbon atom is very important to all life on earth because it can form four covalent bonds with other atoms. Carbon atoms can bond with each other, forming a variety of organic compounds. These organic compounds can take the form of straight chains, branched chains, and rings, as illustrated in the figure below. Carbon compounds are responsible for the diversity of life on Earth. What is organic Chemistry? Why are carbon compounds so important to the diversity of life we see on earth?

2 Macromolecules Biomolecules are macromolecules, which are large molecules that are formed by joining smaller organic molecules together. Macromolecules are also called polymers. Polymers are made from repeating units of identical or nearly identical compounds called monomers. The monomers are linked together by a series of covalent bonds. What are macromolecules? What are Polymers? What s for Supper? Do you like pizza? Many of us do. What happens when you eat a slice of pepperoni pizza or some other food? In your mouth, stomach and small intestine, digestion occurs. The food, mostly large molecules of organic compounds made of carbon and other elements, are broken down into smaller units that your body needs for building its structure, repairing itself and carrying out life s functions. Many different enzymes initiate or speed up the various chemical reactions necessary to break macromolecules down during digestion. Some break proteins apart. Others digest carbohydrates, while still others break apart lipids. This results in smaller molecules that are able to diffuse (move) across the walls of the small intestines and enter the blood stream. From there, they travel to all the body s cells where they provide both the energy and raw materials needed for growth and maintenance. The nutrients in foods can be classified into three broad categories: proteins, carbohydrates and lipids. Carbohydrates are sugars and starches and are are composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio (one oxygen and two hydrogen atoms for each carbon atom: CH 2 O). Monosaccharides (mah nuh SA kuh ridz), are simple sugars like glucose C 6 H 12 O 6 and fructose. A disaccharide (di SA kuh rid) is two monosaccharides linked together. Longer carbohydrate chains are called polysaccharides. In the body, complex carbohydrates (you know, disaccharides and polysaccharides) are broken down into simple sugars like glucose, which is the body s main energy source. A slice of pizza contains What protein speeds up chemical reactions? (see vocabulary) Name three classes of organic compounds 3.) What are monosaccharides? What are disaccharides? What is the difference between a disaccharide and a polysaccharide? Why is glucose so important?

3 carbohydrates in the flower used to make the crust and in the milk used to make the cheese. We learned that carbohydrates serve as energy sources for organisms, but it doesn t stop there. Carbohydrates also provide structural support in the cell walls of plants and in the hard shells of shrimp, lobsters, and some insects. A protein is made of small carbon compounds called amino acids. Amino acids have a distinctive structure. They are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur. They contain an amino group (-NH 2 ) at one end and a carboxyl group (-COOH) at the other. We know that carbohydrates are an important source of energy for all of our cells. Identify two other functions of carbohydrates. What are the building blocks (monomers) of proteins? (what are they made of?) How many amino acids make up the human body? About 20 amino acids make up the human body. The body can make 12 of them, but the other 8 must come from the food we eat. Proteins are made of different combinations of all 20 amino acids. Covalent bonds called peptide bonds join amino acids together to form proteins. Amino acids can be arranged in many different ways to produce a variety of proteins. Proteins are involved in nearly every function of your body. Your muscles, skin, and hair are made of proteins. Your cells contain about 10,000 different proteins that serve many functions. Some proteins are enzymes. They initiate or speed up the chemical reactions that maintain life. The function of a protein depends on its chemical makeup. Proteins: provide structural support; transport substances inside the cell and between cells; communicate signals within the cell and between cells; speed up chemical reactions; control cell growth. How many are made by your body? How does your body get the rest? How are amino acids held together to form a protein? What determines the function of a protein? Identify 3 functions of proteins. 3.)

4 Lipids are molecules made mostly of carbon and hydrogen. The main function of lipids is to store energy. Lipids that are liquid at body temperature are often called oils; those that are solid at body temperature are fats. Like carbohydrates, lipids are made of carbon, hydrogen and oxygen. However, lipids contain relatively more hydrogen and oxygen than carbohydrates of the same size. This means that gram for gram lipids contain more energy than carbohydrates. A lipid called a triglyceride (tri GLIH suh rid) is a fat when solid and an oil when liquid. Plant leaves are coated with lipids called waxes to prevent water loss. What is the main function of lipids? What are the differences between a saturated and an unsaturated fat? Saturated and Unsaturated Fats When the carbon atoms in a fat cannot bond with any more hydrogen atoms, the fat is a saturated fat. The carbon atoms of unsaturated fats can bond with more hydrogen atoms. Phospholipids A lipid called a phospholipid is responsible for the structure and function of the cell membrane. Lipids do not dissolve in water. This characteristic enables lipids to serve as barriers in biological membranes. Steroids Cholesterol and hormones are types of steroids, another group of lipids. In spite of its bad reputation, cholesterol provides the starting point for other important lipids, such as the hormones estrogen and testosterone. Identify two types of steroids?

5 Nucleic acids are the fourth group of biological macromolecules. Nucleic acids are complex macromolecules that store and transmit genetic information. Repeating subunits, called nucleotides, make up nucleic acids Nucleotides are composed of carbon, nitrogen, oxygen, phosphorus, and hydrogen. All nucleotides have the three units shown in the figure below a phosphate, a nitrogenous base, and a sugar. Identify the three parts of a nucleotide: 3.) Circle each nucleotide in the diagram below. To form a nucleic acid, the sugar of one nucleotide bonds to the phosphate of another nucleotide, as illustrated in the figure on the right. The nitrogenous base sticks out from the chain. It is available to bond with bases in other nucleic acids. Two types of nucleic acids are found in living things. One is deoxyribonucleic (dee AHK sih rib oh noo klay ihk) acid, or DNA. The other is ribonucleic (rib oh noo KLAY ihk) acid, or RNA. DNA is the genetic code. DNA stores all the instructions for organisms to grow, reproduce, and adapt. The main function of RNA is to use the information stored in DNA to make proteins. Identify 2 nucleic acids and their functions

6 Analysis Questions 1. Is the compound KMnO4 organic? Explain. 2. You read an essay that shows a compound is 10% nitrogen. Is it a carbohydrate? Explain. 3. What are enzymes made of? 4. From which of the following could a carbohydrate be made of with no elements left over? A.) Carbon dioxide and amino acids B.) Carbon dioxide and water 6. The graph shows the energy required to drive a reaction under two different conditions. Which part of the graph shows the reaction when it occurs in the presence of an enzyme? C.) Hydrogen, oxygen and amino acids D.) Water and nitrogen gas 5. In the human liver, a number of toxic substances are broken down into their harmless components. This process depends on. A.) lipids B.) carbohydrates C.) fatty acids D.) enxymes A.) The solid line B.) The dashed line C.) The highest peak D.) The tallest vertical arrow