Chapter 8 Section 8.1 Essential Nutrients

Chemicals of Life Living things are composed of non-living chemicals. These chemicals are often grouped into four major organic compounds: Carbohydrates Lipids Proteins Nucleic Acids

1. Carbohydrates Carbohydrate – a molecule composed of sugar subunits that contain carbon, hydrogen and oxygen in a 1:2:1 ratio. Ex. Triose Sugars – C3H603 Hexose Sugars –C6H12O6 The main function of a carbohydrate is energy storage. Humans cannot make carbohydrates, we must rely on consuming them from plants.

Carbohydrate Chemistry Carbohydrates are either single sugar units or polymers of many sugar units. A polymer – is a molecule composed of three or more subunits. When you think of polymers think of long molecules formed by linking many small similar chemical subunits.

Carbohydrates can be classified according to the number of sugar units they contain. Monosaccharide – a single sugar unit. Disaccharide – a sugar formed by joining two monosaccharide subunits. Polysaccharide – a sugar composed of three or more single sugar units.

Monosaccharides

Disaccharide

Polysaccharide

2. Lipids Lipids - fats and oils that are insoluble in water (do not dissolve). Their main functions are energy storage and the formation of cellular membranes

Lipid Chemistry Most lipids are composed of two subunits: glycerol + fatty acids. There are two main groups of lipids: Triglycerides Phospholipids

Triglyceride – is a lipid composed of glycerol and three fatty acids. There are two types of triglycerides: saturated fatty acids and unsaturated fatty acids.

Saturated Vs. Unsaturated Saturated Fatty Acids Unsaturated Fatty Acids no double covalent bonds between carbon atoms, so it contains all the possible H atoms it can bond with cause the resulting fat to be solid at room temp. referred to as fat has double bonds between some carbon atoms, leaving room for additional H atoms cause resulting fat to be liquid at room temp referred to as oils

Saturated Vs. Unsaturated

Phospholipid – a lipid with a phosphate molecule attached to the glycerol. To form a phospholipid a negatively charged phosphate replaces one of the fatty acids attached to the glycerol in a triglyceride. Phospholipids are said to be polar because they have a negatively charged head (phosphate) and a positively charged tail (2 fatty acids).

3. Proteins Protein – a molecule made up of a chain of amino acids. Amino acid – a chemical that contains nitrogen; can be linked to form proteins. The main functions of proteins are transport, blood clotting, support, immunity and muscle action. Examples of Proteins - Hemoglobin, collagen, antibodies and enzymes.

Protein Chemistry Proteins are made of several amino acids linked together. Amino acids are linked together by a peptide bond. Due to the peptide bonds a chain of three or more amino acids can also be known as a polypeptide.

Amino Acids

Peptide Bonds

Denaturation and Coagulation Denaturation – the process that occurs when the bonds of a protein molecule are disrupted, causing a temporary change in shape. Ex  Oxygenated hemoglobin vs. deoxygenated hemoglobin Coagulation – the process that occurs when the bonds of a protein molecule are disrupted, causing a permanent change in shape. Ex  Boiling an egg. These processes can be caused by excess heat, radiation or change in pH.

4. Nucleic Acids Nucleic Acids – polymers of nucleotides. Their main function is the transfer and expression of genetic information. Examples of Nucleic Acids are: DNA and RNA

Chemistry of Nucleic Acids A nucleotide is a five carbon sugar attached to 1 of the 4 nitrogen containing bases: Adenine Guanine Cytosine Thymine Many nucleotides put together make up the nucleic acid.

Forming Organic Compounds 3 of the 4 organic compounds (carbs, lipids and proteins) are formed in the same way. This process is known as dehydration synthesis (dehydrolysis). Dehydration synthesis – the process by which larger molecules are formed by the removal of water from two smaller molecules.

In dehydration synthesis an OH group is removed from one molecule and an H is removed from the other compound. This forms a water molecule and connects the two molecules by a covalent bond.

Breaking Organic Compounds These same 3 compounds are broken in the same way. This process is the reverse of dehydration synthesis and is known as hydrolysis. Hydrolysis – the process by which larger molecules are split into smaller molecules by the addition of water.

In hydrolysis when water is added the molecule breaks into its subunits. An OH group is added to one molecule and a H is added to the other molecule.

Formation of a Disaccharide or Polysaccharide

Formation of a Lipid

Formation of a Protein