Unit D: Humans Systems

Essential nutrients Carbohydrates Lipids Proteins Nucleic acids

“Chemicals of Life” macromolecules

The essential nutrients are considered macromolecules because they are large and complex Many are polymers – long chains of small, repeating chemical subunits

Assembling Macromolecules All macromolecules are assembled in the same basic way Dehydration synthesis - removing an -OH group from one subunit and a -H atom from another subunit A molecule of water is removed and a new covalent bond is formed

Disassembling Macromolecules The reverse of dehydration Hydrolysis - a molecule of water is added “water splitting”

Carbohydrates Macromolecules that always contain carbon, hydrogen, and oxygen - and almost always in the same proportion (1 : 2 : 1) Main function - short or long term energy storage 2 main types - simple sugars and polysaccharides

Simple Sugars 3 to 7 carbon atoms Monosaccharides contain a single sugar units Disaccharides contain 2 units

Sucrose (table sugar)

Polysaccharides “poly” = many Many linked simple sugars Ex. starch - repeating units of glucose. Provides energy storage in plants glycogen - repeating units of glucose. Provides energy storage in animals Cellulose – composes cell walls

Foods can be tested for Simple sugars using Benedicts solution The solution is blue and will turn color depending on the amount of sugar present Iodine is used to identify starch (will turn blue-black in the presence of starch)

Lipids insoluble in water Contain carbon, hydrogen and oxygen Main function - energy storage (fats and oils), cell membranes (phospholipids), sex hormones (steroids) When glycogen stores have been built up, excess carbohydrates are converted into fat

Lipid Groups 1. triglycerides Glycerol + 3 fatty acids + Fatty acids may be short, long, saturated, or unsaturated

Saturated vs. Unsaturated Saturated - only single bonds, maximum number of hydrogen atoms Solid at room temperature (FAT) Unsaturated - contains some double bonds Liquid at room temperature (OILS)

Polyunsaturated fats Many double bonds Easily broken down ‘Healthy’ type of fat

2. Waxes Long chains of fatty acids attached to long chains of alcohols or carbon rings Waterproof Phospholipids Have a phosphate molecule attached Found in cell membranes

Foods can be tested for Lipids using Sudan IV indicator Substance will change from dark red to a reddish orange color Brown bag test Substance is put on a brown bag and liquid is left to evaporate. If the bag is translucent – positive test

Proteins Made from amino acids Composed of carbon, hydrogen, oxygen, nitrogen Main function - structure, enzymes, repair and immunity Structurally complex and diverse

Amino acids R-group determines identity of the aa. 20 different types Our body can synthesize 11 - the rest must come from our diet: “essential amino acids”

Peptide bond Amino acids are joined by a peptide bond (dehydration synthesis!)

Chains of aa’s are twisted and coiled into complex 3-dimensional structures The R-group determines solubility (hemoglobin vs. fingernails)

Chemistry of Proteins Denaturation Temporary change in shape of protein because of exposure to extreme heat , radiation or change in pH Coagulation Permanent change in shape of protein If you body does not get any food……. Proteins break down for energy when carbs and lipids have been depleted

Foods can be tested for Proteins by using Biuret’s solution Add the blue solution to your sample; if it turns pink/purple protein is present

Nucleic Acids Largest and most common molecule in living things Building blocks of genetic code Long chains of subunits called nucleotides Main function - transfer and expression of genetic information Two types: DNA and RNA

Vitamins and Minerals Not classified as macromolecules Essential to structure and function of cells but only required in small amounts Vitamins - organic compounds involved in disease resistance, tissue growth, etc. Minerals - inorganic compounds involved in building of bones and cartilage and an essential component of enzymes and hormones, and vitamins

Water- Essential but not a nutrient Absorbs/releases energy (moderate temp) Medium in which reactions take place Excellent solvent 60% of cells’ mass Cushions body organs Lubricates Cleaning(tears/saliva)