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THE STRUCTURE AND FUNCTION OF MACROMOLECULES MACROMOLECULES DEFINED… • Large • Organic (made of carbon compounds) • 4 Classes • Essential for life • Most are polymers (long chains of covalently-bonded building blocks called, “monomers”) • Form by dehydration (removing H2O) • Break apart by hydrolysis (adding H2O) OVERVIEW: 1. Carbohydrates • Roles: fuel, building materials • Sugars 2. Lipids • Roles: energy storage, cell membranes • Fats OVERVIEW: 3. Proteins • Speed up chemical reactions, structural support, storage, transport, cellular communication, movement, defense • Enzymes 4. Nucleic Acids • Store and transmit hereditary information • DNA (deoxyribonucleic acid) CARBOHYDRATES CARBOHYDRATES • Monomers: MONOSACCHARIDES • Multiples of the unit CH2O • Key features: • Carbonyl group (>C=O) • Hydroxyl groups (-OH) • Aldose (aldehyde: =O on end) or Ketose (ketone: =O in middle) • names end in “-ose” • Most form rings in aqueous solutions CARBOHYDRATES • Monosaccharides - Major nutrients for cells and raw material for small organic molecules • Disaccharides – joined by glycosidic linkage (sucrose = glucose + fructose) • Polysaccharides – macromolecules, 100’s to 1,000’s, ex. = starch (energy storage in plants) and glycogen (energy storage in animals), cellulose (plant cell walls), chitin (arthropod exoskeletons) LIPIDS LIPIDS • Do not consist of polymers • Little or no affinity for water • Three kinds • 1. Fats: Energy Storage • Consist of glycerol (alcohol with 3 C’s) and fatty acids (long hydrocarbon chain with a carboxyl group on one end) O=C-OH • Triacylglycerol = 3 FA molecules joined to a glycerol by an ester linkage • Saturated – no double bonds, pack tightly, solid @ room temp., animal fat; Unsaturated = at least 1 double bond, pack less tightly, liquid @ room temp, plant fats LIPIDS • Three kinds (continued) • 2. Phospholipids: Cell Membranes • Only 2 FA’s attached to a glycerol (hydrophilic head & hydrophobic tail) • Bilayers shield hydrophobic regions from water • 3. Steroids • 4 fused rings (with varying functional groups) • Ex. = cholesterol – a component of animal cell membranes, precursor for other steroids (such as hormones) PROTEINS PROTEINS • Many different functions (named earlier) • Enzymes are very important • Catalysts – speed up chemical reactions without being consumed • Structures are diverse • 20 different Amino Acids = building blocks • Each has an amino group (N), a carboxyl group (O & OH), and an “R” group • Can be Nonpolar (hydrophobic), Polar (hydrophilic), or Charged (acidic/basic) • Many amino acids = polypeptide; 1 or more polypeptides folded into a unique shape = protein • Peptide bonds join amino acids together PROTEINS • 4 Levels of Protein structure: • 1. Primary – sequence of amino acids; like order of letters in a word • 2. Secondary – coils/folds in protein structure; alpha helix, beta pleated sheet; results from interactions of the polypeptide backbone (H and O) • 3. Tertiary – overall shape resulting from interactions between R groups (side chains); hydrophobic interactions, disulfide bridges (sulfhydryl groups –SH bond) • 4. Quaternary – 2 or more polypeptide chains aggregated into one functional macromolecule; example: hemoglobin (has 4 subunits) PROTEINS • Changes in Conformation: when shape is changed, ability to function changes; Example: sickle cell disease (abnormal hemoglobin deformed blood cells blood clots) • Denaturation – unraveling of protein due to pH, salt, temperature, etc. • Chaperonins – proteins that assist with folding other proteins NUCLEIC ACIDS NUCLEIC ACIDS • http://thatsafacttv.com/ • Instructions for building proteins is found in genes, which consist of DNA • DNA: deoxyribonucleic acid • Genetic information inherited from parents • Bound in structures called, “chromosomes” • Sugar, phosphate, base “nucleotide” building blocks • Ribose/deoxyribose = sugar • Pyrimidine (5C ring) (C,T) / purine (6C ring) (A,G) = base • Complimentary bases: Cytosine-Guanine; Thymine-Adenine • Found in nucleus of cells • Double helix • Strand direction is 5’ to 3’, antiparallel strands (like a highway) NUCLEIC ACIDS • RNA: ribonucleic acid • mRNA = a copy of the DNA code that interacts with proteinsynthesizing machinery (“ribosomes”) to make a polypeptide • Single stand • Uracil instead of Thymine