Students should be able to:
All living matter is composed of basic units of matter called atoms. Atoms can chemically bond to form molecules. The chemical bonding of atoms can be ionic (atoms are held together by electronic attraction due to gain or lose of the atom's electrons) or they can be covalent (atoms "share" their electrons). You will study these two types of bonding this laboratory exercise.
The chemical bonding of atoms forms either ionic bonds (formula units), or covalent bonds (molecules). In ionic bonding, atoms lose or gain electrons. If an atom loses electrons it is termed a cation. If it gains electrons then it becomes an anion.
Chemically bonded compounds can be either inorganic or organic. Inorganic compounds are generally ionically bonded, while organic compounds are covalently bonded.
This lab will concentrate more on the organic compounds. Their structure, composition, chemical properties, and importance to living organisms will be addressed. There are four major classes of organic compounds. They are carbohydrates (sugars and starches), proteins, lipids (fats and oils) and nucleic acids (DNA and RNA).
Large organic molecules (ones with 1000's of atoms) are formed from smaller units called monomers. Monomers, such as glucose sugar, chemically bond together by dehydration synthesis (water is formed). These chemically bonded monomers (chains, rings, etc.) form polymers, such as starch. the bonded polymers can be broken apart by the addition of water (and enzymes), in a process called hydrolysis.
Carbohydrates are a group of important organic compounds. They consist of sugars, which can be classified as monosaccharides, or disaccharides, or starches, which can be polysaccharides or oligosaccharides. The monomer of carbohydrates is usually the monosaccharide, glucose (C6H12O6) It is chemically bonded (dehydration synthesis) to other glucose molecules or other sugars to form large single or branched chains or sometimes rings. You will be building models of glucose and chemically testing for sugars and starches in this lab exercise.
Proteins are another group of important organic compounds. The are formed from monomer units called amino acids. There are 20 types of amino acids, that can go into the formation of proteins. Each amino acid consists of a central carbon atom, to which is chemically bonded four other chemical entities. These include an amino group, a carboxyl group (organic acid), an R group (which is what determines the kind of amino acid) and a hydrogen atom. You will be building amino acid models and chemically testing for proteins in this lab exercise.
Lipids, fats and oils, are important to living organisms too. They are formed by chemically bonding fatty acids to a glycerol base. Fats are generally insoluble in water, but soluble in alcohols and ether. Fats are generally solids, whereas oils are liquid. Fats are generally associated with animals and oils with plants. There are many types of lipids that have biological significance. These are fats, oils, phospholipids (form cell membrane), cholesterol and steroids (not a true lipid). You will be building models of the glycerol, and chemically testing for lipids in this lab exercise.
Nucleic acids, DNA and RNA, are important molecules from a genetic and functional standpoint. Nucleic acids are formed from nucleotide units. The nucleotides found in the DNA molecule are adenine, thymine, guanine and cytosine. In RNA the same ones are found except uracil replaces thymine. You will be building a model of DNA during this lab exercise.
Print out the following materials. Make sure you read them before coming to lab.
The Laboratory Activities and Data Collection
Lab Activity #1 - Molecular Modeling
Lab Activity #2 - Chemical Testing for Carbohydrates - Starch
Lab Activity #3 - Chemical Testing for Carbohydrates - Sugars
Lab Activity #4- Chemical Testing for Proteins
Lab Activity #5 - Chemical Testing for Lipids
Post-lab Activity and Data Analysis
Results and Analysis: