Building Complex Molecules That Comprise Living Things Macromolecules Building Complex Molecules That Comprise Living Things

Four types of organic macromolecules are important in living systems. Comparison of Terms Molecule Two or more atoms joined by chemical bonds Macromolecule Large polymer made of repeating monomer units Four types of organic macromolecules are important in living systems.

Macromolecules: Polymers Made of Repeating Monomers Monomer Unit Carbohydrates Sugars Lipids Fatty acids Proteins Amino acids Nucleic Acids Nucleotides

Organic Macromolecules Contain Carbon Question: How many electrons does carbon need to fill its outer energy level? Answer: Four Each carbon atom can make four covalent bonds with other types of atoms or additional carbons.

Carbon atoms can be joined by single, double or triple bonds. double bond Carbon atoms can be joined by single, double or triple bonds.

Synthesis and Breakdown of Macromolecules Dehydration Synthesis Removal of water to add monomer units Hydrolysis Addition of OH and H groups of water to break a bond between monomers

Dehydration Synthesis / Hydrolysis

Carbohydrates: Structure Simple Monosaccharides= one sugar unit Glucose = blood sugar All cells use glucose for energy

Chemical Formula for a Six-Carbon Sugar

Carbohydrates: Structure Simple Disaccharides = two sugar units Oligosaccharides (“oligo-” means few or scant). Several monosaccharides joined together. Sucrose (table sugar) is disaccharide of one glucose and one fructose (Fig 3-1, p39). Often combined with other molecules. Many larger molecules have oligosaccharides attached for various purposes. Sometimes used for cell ID. The cell membrane has many proteins in it, some of which have attached oligosaccharides projecting away from the cell. Sometimes these are used as chemical labels for cell type. CH2OH H HO OH O Glucose CH2OH H HO OH O HOCH2 O HOCH2 H CH2OH HO Fructose + HO H Sucrose & Water

Carbohydrates: Structure Simple Disaccharides = two sugar units Sucrose = glucose + fructose table sugar Lactose = glucose + galactose milk sugar Maltose = glucose + glucose seed sugar

Carbohydrates: Structure Complex Polysaccharides= many sugar units Starch -- storage in plants Glycogen -- storage in animals Cellulose -- plant cell walls, indigestible (fiber)

Carbohydrates: Functions Energy source Structural component Cell-cell communication

Mac ‘n Cheese Nutrition Label Nutrition Facts Serving Size 1 cup (228g) Servings Per Container 2 Start here Amount Per Serving Calories 250 Calories from Fat 110 % Daily Value Total Fat 12g 18% Saturated Fat 3g 15% Limit these nutrients Trans Fat 1.5g Cholesterol 30mg 10% Sodium 470mg 20% Total Carbohydrate 31g 10% Dietary Fiber 0g 0% Sugars 5g Get enough of these nutrients Protein 5g Vitamin A 4% Vitamin C 2% Calcium 20% Iron 4%

Applying Your Knowledge Monosaccharide Polysaccharide Disaccharide Which molecule consists of two sugar units? Which choice best describes glycogen? Which type of molecule provides the basic energy for your cells? Which type of molecule is found in milk?

Lipids: Structure Triglyceride—predominant form in diet One molecule of glycerol Three fatty acids

Lipids: Structure Types of Fatty Acids Saturated – 2H per internal carbon Unsaturated -- <2H per internal carbon one or more double bonds Monounsaturated – one double bond Polyunsaturated – more than one double bond

Triglyceride Formation H C OH O C H Glycerol Remove These Waters C O H This shows how water is removed from three fatty acids and glycerol to make a fat and water. C OH O H C OH O H C OH O H C O H Add 3 Fatty Acids HOH 3 Waters

Physical dispersion of lipids Emulsification Physical dispersion of lipids Mixing with a molecule having a polar and non-polar end Bile from gall bladder emulsifies fats prior to digestion

Lipids: Structure Phospholipid—component of cell membranes Hydrophilic Polar Head Glycerol Fatty Acid Tails Hydrophilic Hydrophobic

Lipids: Structure Steroids Linked carbon rings Natural body components Hormones Cholesterol Complex ring forms Some hormones, especially those produced by the adrenal gland and sex hormones. Cholesterol Natural substance; not necessarily bad for you. Found in membranes in between the fatty acid tails of phospholipids. Athletes beware of androgenics! Dangerous chemicals. Please reconsider your value system if you use these. If you use them, you WILL regret it!

Steroids Cholesterol Estradiol Testosterone

Lipids: Functions Concentrated energy source Structural components of cell membranes Phospholipids Cholesterol Communication Steroid Hormones Protection from water Waxes Cholesterol Phospholipids

Mac ‘n Cheese Nutrition Label Nutrition Facts Serving Size 1 cup (228g) Servings Per Container 2 Start here Amount Per Serving Calories 250 Calories from Fat 110 % Daily Value Total Fat 12g 18% Saturated Fat 3g 15% Limit these nutrients Trans Fat 1.5g Cholesterol 30mg 10% Sodium 470mg 20% Total Carbohydrate 31g 10% Dietary Fiber 0g 0% Sugars 5g Get enough of these nutrients Protein 5g Vitamin A 4% Vitamin C 2% Calcium 20% Iron 4%

Applying Your Knowledge Polyunsaturated fatty acid Cholesterol Monounsaturated fatty acid Saturated fatty acid Which molecule is made of a series of carbon rings? Which molecule has more than one double bond? Which molecule has 2H for each internal carbon? Which molecule has one double bond?

The “R” Group Differs for Each Amino Acid Proteins: Structure Primary structure = chain of amino acids Amino acids have common features Carboxylic Acid Group Amino Group     See p 34 R Central Carbon The “R” Group Differs for Each Amino Acid

Proteins: Structure Forming the Protein Chain Phenylalanine Leucine Here we position two amino acids close together so that the amine group of one is close to the carboxyl group of the other. Note that a -H is hanging out from one, and a -OH from the other. These will be broken off (by an enzyme) to form water. The remaining bonds of the two amino acids will be connected to form a dipeptide (two amino acids joined by a peptide linkage). Dehydration Synthesis between COOH & NH2

Proteins: Structure Forming the Protein Chain The Peptide Bond Water Phenylalanine-Leucine Dipeptide

Four Levels of Protein Structure Primary (Sequence) Tertiary (Folding by R-group interactions) Depending on the sequence of amino acids, the polypeptide chain can either form a spiral like the tube on the left, or a pleated sheet like on the right. Some proteins have a spiral section followed by a sheet section, etc. Fig 2.26, p35. Quaternary (Two or more chains associating) Secondary (Coiling by Hydrogen Bonding)

Four Levels of Protein Structure Primary Structure = sequence of amino acids in chain

Four Levels of Protein Structure Secondary Structure Folded structure due to hydrogen bonds between the amino and acid groups of amino acids N C N C H O H or O O H O H C N C N

Found in most proteins Found in silk

Four Levels of Protein Structure Tertiary Structure: Three dimensional folded structure due to attractions and repulsions between R groups Can involve covalent bonding hydrogen bonding ionic interactions hydrophilic and hydrophobic interactions

Hair Curling Straight Hair Naturally Curly Hair | S | S | | S | S |

Four Levels of Protein Structure Quaternary Structure: Association of two or more protein chains eg. Hemoglobin is composed of 4 protein chains 2 are called alpha hemoglobin 2 are called beta hemoglobin

Denaturation of Proteins Disruption of secondary, tertiary or quaternary protein structure Caused by heat or changes in pH Irreversible, causes loss of protein function protein unfolds

Proteins: Functions Structural Component of Cells Control of Metabolic Reactions: enzymes Maintain homeostasis Transport substances in blood Antibodies protect against invaders Growth and Repair Support and Motion Communication Protein Hormones Cell Receptors Energy source Protein Protein

Applying Your Knowledge Primary Secondary Tertiary Quaternary Which structure results from hydrogen bonding? Which structure involves an association of two or more protein chains? Which structure describes the linear sequence of amino acids? Which structure depends upon interactions between the R groups of the amino acids?