The Structure and Function of Macromolecules: Carbohydrates Chapter 5 p Polymer Principles Macromolecule: a giant molecule formed by joining smaller molecules Polymer: a type of macromolecule consisting of repeating building blocks, joined by covalent bonds i.e.: proteins, carbs, nucleic acids Monomer: a building block of a polymer MMonomers are linked using a dehydration reaction H 2 O lost Uses energy; requires enzymes PPolymers are broken down by hydrolysis H 2 O gained i.e. digestion: food must be broken down to enter cells; enzymes help Monomers can create can immense variety of polymers Each cell has 1,000s different macromolecules Constructed from only monomers (like alphabet) Ordering is the key to variety Carbohydrates Fuel and Burning Material Carbs include both sugars and their polymers Classified by: Location of carbonyl (aldose or ketose) Length of C skeleton Spatial arrangement Simple Sugars fuel & C source AAll have molecular formula in some multiple of CH 2 O (carbohydrate) MMost are arranged in rings PProvide energy for cells i.e.: cell respiration SServe as raw material for other organic molecules i.e.: amino acids & fatty acids Disaccharides 22 monosaccharides joined by glycosidic linkage (a dehydration rxn) EExamples: Maltose: 2 glucose; malt sugar Sucrose: 1 glucose/1 fructose; table sugar Lactose: 1 glucose/1 galactose; found in milk Polysaccharides storage & structure 1100s 1,000s monosaccharides joined by glycosidic linkage SStructure and function determined by monomers involved & position of linkages Storage Polysaccharides Starch: storage in plants, composed of only glucose Releases sugar for energy through hydrolysis Glycogen: storage in humans, also only glucose but branched Stored in liver & muscles Releases glucose when needed through hydrolysis Structural Polysaccharides CCellulose: provides tough, structural support for plant cell walls Composed of glucose, but w/ different ring shapes Hydroxyl group of 1 cellulose forms H- bond w/ another to form microfibrils in plant cell walls The Structure and Function of Macromolecules: Lipids Chapter 5 p Lipids Diverse Hydrophobic Molecules NOT polymers very diverse All are hydrophobic; mostly hydrocarbons 3 main families: Fats Phospholipids Steroids Fats store large amounts of energy CComposed of: 1 Glycerol: alcohol w/ 3 carbons 3 Fatty Acids: long C skeleton w/carboxyl on end (acid) & hydrocarbon chain Triacylglycerol = 3 fatty acid tail attached to a glycerol head Fatty Acids: May be all 3 same or different Vary in length & in # & location of double bonds Saturated: no double bonds room temp; animal fat Unsaturated: 1+ double bonds room temp; plant & fish fat FFat Storage Major function of fats is energy storage IIn plants: seeds (if not starch) IIn animals: adipose cells Shrink & swell with fat (energy) movement Phospholipids SSimilar to fats but with only 2 fatty acid chains & 1 phosphate group (-) Tail: hydrophobic Head: hydrophilic When placed in H 2 O, will rearrange to protect hydrophobic tails Steroids CComposed of C skeleton w/ 4 rings and different functional groups CCholesterol: Component of animal cell membranes Precursor to other steroids The Structure and Function of Macromolecules: Proteins Chapter 5 p Proteins: Many structures, many functions PProteins make up > 50% dry weight cells HHumans have 10,000s proteins all w/different structures and functions PPolypeptide: polymer constructed from 20 monomers called amino acids Protein: 1+ polypeptide coiled into specific shape Polypeptide: Polymer of amino acids AAmino Acid: is composed of 1) Amino 2) Carboxyl 3) Asymmetric C 4) Side chain DDiffers in each a.a.; determines a.a. properties: A) non-polar, hydrophobic B) polar, hydrophilic C) acidic (-), hydrophilic D) basic (+), hydrophilic Peptide Bonds TThe carboxyl group of 1 a.a. joins covalently to amino group of adjacent a.a. Dehydration rxn resulting in peptide bond Repeated many times to form polypeptide Each polypeptide has unique sequence of amino acids Protein Function depends on Conformation Protein = 1+ polypeptides coiled into unique shape Function of protein depends on its ability to bind to another molecule 4 Levels of Protein Structure AAs polypeptide forms, usually fold spontaneously to functional shape Folding actually occurs as a sequence of bonds form PPrimary Structure Unique sequence of a.a., determined by genetic info. Even slight change may affect ability to function ii.e. sickle cell anemia caused by 1 a.a. substitution SSecondary Structure Segments of polypep. chain repeatedly fold to contribute to overall structure Due to H-bonds at regular intervals along C backbone ii.e.: helix = coiled pleated sheet = helps strength of fibrous proteins TTertiary Structure Irregular contortions from interaction btwn side chains of a.a Caused by: HHydrophobic interactions (non- polar sides fold in) DDisulfide bridges (form btwn 2 cysteine a.a.) QQuarternary Structure Involve 2+ proteins folded together ii.e.: Collagen 3 helical polypeptides braided; gives strength to tendons, bones, etc. Protein Structures Denaturation UUnder hostile conditions proteins may become unfolded & thus inactive CCaused by changes in: pH, salt conc., temp., solvent IIf denaturing agent removed, protein will regain shape The Structure and Function of Macromolecules: Nucleic Acids Chapter 5 p Nucleic Acids: Informational Polymers TThe amino acid sequence (primary struc.) of proteins is determined by genes GGenes are composed of DNA, a polymer of nucleic acids Nucleic Acids Store & transmit hereditary info 2 types: DNA: deoxyribonucleic acid Provides directions for own replication Directs RNA synthesis RNA: ribonucleic acid Controls protein synthesis DDNA: The genetic material inherited from parents Codes for the info that controls all cell activities (hardware) Proteins are required to carry out activities (software) RRNA: Each DNA gene codes for an mRNA molecule mRNA takes info to ribosomes, which decode it to make amino acids, then proteins A Nucleic Acid is a polymer of nucleotides Nucleotide is composed of: 1) Nitrogenous Base (organic) A) Pyrimidines: 6 C ring w/N Cytosine, Thymine (DNA only), Uracil (RNA only) B) Purines: 6 C ring w/ 5 C ring Adenine, Guanine 2) Pentose (5 C sugar) A) DNA: deoxyribose B) RNA: ribose 3) Phosphate Group (functional group) Nucleotide Structure Polynucleotide AA nucleic acid polymer Nucleotides joined by covalent bonds called phosphodiester linkages Creates backbone of sugar-phosphate & appendages of N bases Order of N bases determines amino acid sequence, and thus protein Inheritance is based on DNA replication DNA molecule = 2 polynucleotide chains intertwined in double helix Backbone outside N bases pair up chain-to-chain on inside Purine Prymidine Very specific Strands are complementary