Organic Compounds Necessities for Life

What is an organic compound? In Biology, the word organic means “relating to organisms” NOT food grown without the use of pesticides, antibiotics, or other industrial chemicals. All organic compounds contain covalently bound carbon. Organic compounds can also be synthesized in the lab.

MACROmolecules are giant and are. . . formed by polymerization, in which large compounds (polymers) are built from joining smaller units (monomers) together.

Four Groups of Organic Compounds Carbohydrates, lipids, nucleic acids, and proteins are needed by all living things.

Carbohydrates (sugars) main source of energy for organisms can also be used for structural purposes made of C, H, and O; usually in a 1:2:1 ratio The monomers of carbohydrates are called monosaccharides, like glucose, fructose (in fruits) and galactose (in milk). The breakdown of monosaccharides supplies immediate energy. usually end in –ose.

Carbohydrates cont’d Extra sugar is stored as macromolecules called polysaccharides. Polysaccharides are made from monosaccharides.

Uses of Polysaccharides Many animals store extra sugar as glycogen. Glycogen stored in your muscle supplies energy for contractions. Glycogen stored in your liver is released when glucose in your blood runs low. Plants store excess sugar as starch. Plants also make cellulose, a strong, rigid fiber used for support.

Starch

Glycogen – general structure

Cellulose

Lipids (fats, oils, and waxes) uses: long-term energy storage, insulation, waterproof covering, part of biological membranes, chemical messengers (steroids) contain mostly carbon and hydrogen generally not soluble in water

Lipids Many lipids are formed when a glycerol molecule combines with fatty acids. If all carbon atoms have only single bonds, the lipid is saturated. It holds as many hydrogen atoms as possible. Animation of triglyceride formation

Lipids If there is at least one double bond between carbon atoms, the lipid is unsaturated. Unsaturated lipids like cooking oils tend to be liquid at room temperature.

Steroids – special lipids Cholesterol Sex hormones Birth control pills Cortisone Anabolic steroids

Proteins have many functions They can provide structural support in bones and muscles, form parts of cell membranes, function as hormones to regulate the body, form antibodies to protect against infection, and increase the rate of chemical reactions to name a few.

Proteins are macromolecules. contain nitrogen, carbon, hydrogen, and oxygen (most also have sulfur) The monomers of proteins are amino acids. Amino acids contain an amino group, a carboxyl group, and a variable R-group.

When the amino acids join, they form a polymer called a polypeptide When the amino acids join, they form a polymer called a polypeptide. The monomers are held together by peptide bonds. More than 20 different amino acids are found in nature. Since the R-group varies, it allows for much variety. That is why proteins have so many functions.

Proteins have four levels of organization. This allows for the unique shape of proteins. Shape is very important; if a protein is not the right shape, it will not work.

Primary structure A sequence of amino acids

Secondary structure Hydrogen bonding leads to a spiral structure

Tertiary Structure Ionic bonding Hydrophobic interactions Disulfide Hydrogen

Quaternary Structure Hemoglobin consists of 2 alpha chains and 2 beta

Enzymes – a special type of protein Enzymes are biological catalysts, which work to speed up a chemical reaction. Without enzymes, several reactions in cells would never occur or happen to slowly to be useful.

Nucleic Acids store and transmit hereditary, or genetic, information contain hydrogen, carbon, nitrogen, oxygen, and phosphorus The monomers of nucleic acids are nucleotides, which contain three parts: a 5-carbon sugar, a phosphate group, and a nitrogen base. examples: DNA and RNA ATP

LATER We will study nucleic acids later – when we study genetics!