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 2. Lipids Roles: fuel, building materials Sugars Roles: energy storage, cell membranes Fats

Overview: 3. Proteins 4. Nucleic Acids Speed up chemical reactions, structural support, storage, transport, cellular communication, movement, defense Enzymes 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 protein- synthesizing machinery (“ribosomes”) to make a polypeptide Single stand Uracil instead of Thymine