What does it mean to be a MACROmolecule? You must be a Large molecule You have a complex structure Macromolecule“little” molecule
I. Most macromolecules are polymers, built from monomers What is a polymer? • Poly = many; mer = part. • A long molecule made of monomers bonded together What is a monomer? • A monomer is a sub-unit of a polymer.
Three of the classes of life’s organic molecules are polymers • Carbohydrates, Proteins, Nucleic acids
A. Making and Breaking Polymers How do monomers bind to form polymers? • condensation reactions called dehydration synthesis (removal of water)
How can polymers break down when monomers are needed? Hydrolysis reaction • Hydro = water; lysis = break • Water is added and the lysis of the polymer occurs.
What are Carbohydrates? • Sugars and their polymers • Carbo = carbon, hydrate = water; carbohydrates have the molecular formula (CH2O)n Functions of Carbohydrates in living things: • Major fuel/energy source • Can be used as raw materials for other Macromolecules • Complex sugars = building material in plants What is the Carbohydrate Monomer? • Monosaccharide (“mono” = one; “saccharide” = sugar)
1. Structure of Monosaccharides Contain only C, H, O Hydroxyl group is attached to each carbon One carbon contains a carbonyl group
• Classified according to the size of their carbon chains and location of Carbonyl group
In aqueous solutions many monosaccharides form rings:
2. Structure of Disaccharides Consist of two monosaccharides Are joined by a glycosidic linkage What reaction forms the glycosidic linkage? • Dehydration synthesis
3. Polysaccharides Structure: Polymers of a few hundred or a few thousand monosaccharides. Functions: energy storage molecules or for structural support:
Starch is a plant storage form of energy, easily hydrolyzed to glucose units
Cellulose is a fiber-like structural material made of glucose monomers used in plant cell walls
Why is Cellulose so strong? Glucose monomers are flipped to expose equal Hydroxyl groups on either side of the chain When Cellulose chains are lined up next to each other, they Hydrogen Bond making a strong material that’s difficult to break!
Glycogen is the animal short-term storage form of energy Glucose monomers
Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls.
B. LIPIDS What are Lipids? • Fats, phospholipids, steroids, waxes, pigments • Hydrophobic (“hydro”=water; “phobic” = fearing) • Consist mostly of hydrocarbons • Do NOT consist of polymers
Functions of Lipids in living things: • Energy storage • membrane structure • Protecting against desiccation (drying out). • Insulating against cold. • Absorbing shocks. • Regulating cell activities by hormone actions.
1. Structure of Fats (Triglycerides) Consist of a single glycerol and usually three fatty acids Glycerol – an alcohol with three carbons Fatty Acid - Long Hydrocarbon chains with a Carboxyl group at one end.
Saturated and Unsaturated Fats Unsaturated fats : • one or more double bonds between carbons in the fatty Oleic acid acids allows for “kinks” in the tails • liquid at room temp cis double bond (b) Unsaturated fat and fatty acid causes bending • most plant fats Saturated fats: • No double bonds in fatty acid tails • solid at room temp • most animal fats Stearic acid (a) Saturated fat and fatty acid
C. Proteins What are Proteins? • Chains of amino acid monomers connected by peptide bonds • Have a 3 dimensional globular shape
Examples of Protein Functions Immune System • Binding of antibodies (proteins) to foreign substances Transport • Membrane transport proteins that move substances across cell membranes • Hemoglobin carries oxygen, iron, and other substances through the body. Muscle Contraction • actin and myosin fibers that interact in muscle tissue. Signaling • Hormones such as insulin regulate sugar levels in blood.
Amino Acids Monomers of polypeptides • Molecules with carboxyl and amino groups • Differ in their properties due to differing side chains, called R groups
20 different aminoacids existThe sequence ofamino acids and theinteractions of thedifferent amino acidsdetermine a proteinsshape
Peptide bonds connect amino acids to form polypeptide chains One or more polypeptide chains make up a protein
Proteins are very complex! Their specific structure determines their function.HEMOGLOBIN: Transport of ACTIN: Filament involved ingases and iron in blood muscle contraction
Four Levels of Protein Structure Primary structure HN + 3 Gly ProThr Gly Glu Thr Gly Amino acid Amino end Cys LysSeu subunits • Is the unique sequence of LeuPro Met Val Lys Val amino acids in a Leu Asp AlaVal Arg Gly Ser Pro Ala polypeptide Glu Lle Asp Thr Lys Ser Lys Trp Tyr Leu Ala Gly lle Ser ProPheHis Glu His Ala Glu Val Ala Thr PheVal Asn lle Thr Asp Tyr Ala Arg Ser Arg Ala GlyPro Leu Leu Ser Pro SerTyr Tyr Thr Ser Thr Ala Val o Val ThrAsnProLys Glu c o– Figure 5.20 Carboxyl end
Secondary structure • Is the folding or coiling of the polypeptide into a repeating configuration resulting from hydrogen bonding of amino with carboxyl groups • Includes the α helix and the β pleated sheet β pleated sheet O H O H O O H H H H H H RAmino acid C C N R C C N R C C N C C N N N C N subunits C N R CC R C C R C R C C H O H O H O H O H H H R R R R O O C O C O C C H H H H C N C N H C N C N H C N C N H C N C N H H H H C H O C H O C H O C H O C R R R R R C H C H N H O C N H O C N O C H O C N H α helix C H C R H R H C R H C R N H O C N H O C O C N H O C N C C H R R H HFigure 5.20
Tertiary structure • Is the overall three-dimensional shape of a polypeptide • Results from interactions between amino acids and R groups Hydrophobic interactions and CH CH van der Waals CH22 H3C CH3 interactions O Hydrogen H H3C CH3 Polypeptide bond O CH backbone HO C CH2 CH2 S S CH2 Disulfide bridge O CH2 NH3+ -O C CH2 Ionic bond
Quaternary structure • Is the overall protein structure that results from the aggregation of two or more polypeptide subunits
Chaperonins • Are protein molecules that assist in the proper folding of other proteins Correctly folded Polypeptide protein CapHollowcylinder Chaperonin Steps of Chaperonin 2 The cap attaches, causing the The cap comes 3 (fully assembled) Action: cylinder to change shape in off, and the properly 1 An unfolded poly- such a way that it creates a folded protein is peptide enters the hydrophilic environment for the released. Figure 5.23 cylinder from one end. folding of the polypeptide.
Sickle Cell Disease: A simple change in Primary Structure
Enzymes Are a type of protein that acts as a catalyst, speeding up chemical reactions up to 10 billion times faster than they would spontaneously occur.
Environmental Factors That Determine Protein Conformation Change in environment may lead to denaturation of protein (pH, temperature, salinity, etc.) Denatured protein is biologically inactive Can renature if primary structure is not lost
D. Nucleic Acids : The stuff of Genes Nucleic acids store and transmit hereditary information Genes • Are the units of inheritance • Program the amino acid sequence of polypeptides • Are made of nucleic acids
Two Kinds of Nucleic Acids DNA (Deoxyribonucleic acid) • double stranded • can self replicate • makes up genes which code for proteins is passed from one generation to another RNA (Ribonucleic acid) • single stranded • functions in actual synthesis of proteins coded for by DNA • is made from the DNA template molecule
1. Nucleotide Monomer Structure Both DNA and RNA are composed of nucleotide monomers. Nucleotide = 5 carbon sugar, phosphate, and nitrogenous base Deoxyribose in DNA Ribose in RNA
2. Building the Polymer Phosphate group of one nucleotide forms strong covalent bond with the #3 carbon of the sugar of the other nucleotide.
DNA:• Double helix• 2 polynucleotide chains woundinto the double helix• Base pairing between chainswith H bonds•A-T•C-G