2.3 Carbon Based Molecules

1. 2.3 Carbon Based Molecules Organic molecules are molecules that are carbon based. Carbon atoms have four electrons available for bonding in their outer energy level. They will form four covalent bonds to become stable. Carbon atoms can share one, two or three electrons, creating single, double or triple bonds.

2. Carbon atoms can form straight chains, branched chains, or rings. Compounds that have the same chemical formula, but different three-dimensional structures are called isomers. * glucose and fructose are both C6 H12 O6, but the molecules are in different arrangements. Biomolecules- large organic compounds. Polymers- small molecules that bond together to form chains creating a larger molecule.

3. I. Carbohydrates; biomolecule composed of carbon, hydrogen and oxygen in a ratio of two hydrogen atoms, and one oxygen, for every carbon atom. CH2O A. monosaccharides; simple sugars such as glucose and its isomer fructose. B. disaccharides; a carbohydrate composed of two monosccharides. Sucrose (table sugar) is formed by glucose and fructose bonding with one another.

4. C. polysaccharides; polymers composed of many monosaccharides. 1. Starch; branched chains of glucose polymers used by plants for food storage in seeds and bulbs. 2. glycogen; highly branched glucose polymer used for energy storage in mammals. 3. cellulose; long chains of glucose units that form the cell walls of plants.

5. II. Lipids; Mostly carbon and hydrogen with small amounts of oxygen. These form fats, oils, waxes and steroids. (cholesterol is an example of a steroid) Important for energy storage, insulation, and protective coverings in cells. Lipids are insoluble in water because their molecules are nonpolar and not attracted by water molecules.

6. A. saturated fatty acids; found in some meat and dairy products. Cannot bond with any more hydrogen atoms. O≡C−CH2−CH2−CH2−CH2−CH2−CH2−CH3 B. unsaturated fatty acids; can bond with more hydrogen atoms when double bonds are broken. Found in some vegetable oils. O≡C−CH2−CH2−CH2═CH2−CH2−CH2−CH3

7. III. Proteins; polymer made out of amino acids. A. Proteins regulate cell functions and build cell structures. B. Amino acids are composed of carbon, hydrogen, oxygen and nitrogen (sometimes sulfur). There are 20 common amino acids that are used by cells. The number and sequence of amino acids determines the shape of a protein. The shape of a protein is important in allowing it to carry out its function within the cell.

8. H (hydrogen atom) │ (Amino group) NH2 ─ C ─ COOH (carboxyl group) │ R (variable group); makes each amino acid different Each amino acid contains a central carbon atom to which are attached a carboxyl group, a hydrogen group, and an amino acid group, and a variable group that makes each amino acid different.

9. C. Peptide bonds are covalent bonds between amino acids. Peptide bond H  H H │ │ │ NH2 ─ C —C——— N ― C ― COOH │ ║ │ R O R

10. D. Enzymes; Type of protein that changes therate of metabolic reactions. Activities depend on; 1. temperature; speed of reaction increases with temperature increase. 2. ionic conditions. 3. pH of surroundings.

11. IV. Nucleic acids; made from small units called nucleotides, nucleic acids store cellular information in the form of a code. Nucleotides are made of carbon, hydrogen, oxygen, and phosphorous atoms. These atoms are arranged in three groups to form a nucleic acid; phosphate group, sugar, and a nitrogenous base. A. deoxyribonucleic acid; double stranded helix. Contains the genetic information that is passed from parents to offspring.

12. B. ribonucleic acid; single strand. Makes a copy of DNA strand. Used for making proteins, and transferring genetic code.