Macromolecules Chapter 3

Macromolecules are polymers, built from monomers A polymer is a long molecule consisting of many similar building blocks These small building-block molecules are called monomers Three of the four classes of life’s organic molecules are polymers: Carbohydrates Proteins Nucleic acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Synthesis and Breakdown of Polymers A condensation reaction or more specifically a dehydration reaction occurs when two monomers bond together through the loss of a water molecule Enzymes are macromolecules that speed up the dehydration process Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Dehydration removes a water molecule, forming a new bond H2O Fig. 5-2a HO 1 2 3 H HO H Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond H2O Figure 5.2 The synthesis and breakdown of polymers HO 1 2 3 4 H Longer polymer (a) Dehydration reaction in the synthesis of a polymer

HO 1 2 3 4 H H2O HO 1 2 3 H HO H (b) Hydrolysis adds a water Fig. 5-2b HO 1 2 3 4 H Hydrolysis adds a water molecule, breaking a bond H2O Figure 5.2 The synthesis and breakdown of polymers HO 1 2 3 H HO H (b) Hydrolysis of a polymer

Carbohydrates OH H HO CH2OH O Energy Molecules

Carbohydrates are composed of C, H, O (CH2O)x C6H12O6 Function: energy u energy storage raw materials u structural materials Monomer: sugars ex: sugars, starches, cellulose (CH2O)x C6H12O6 carb = carbon hydr = hydrogen ate = oxygen compound sugar

Sugars 6 5 3 Most names for sugars end in -ose Classified by number of carbons 6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde) Glyceraldehyde H OH O C OH H HO CH2OH O Glucose H OH HO O Ribose CH2OH 6 5 3

energy stored in C-C bonds Numbered carbons C 6' C O 5' C C 4' 1' energy stored in C-C bonds C C 3' 2'

Simple & complex sugars Monosaccharides simple 1 monomer sugars glucose Disaccharides 2 monomers sucrose Polysaccharides large polymers starch OH H HO CH2OH O Glucose

Polysaccharides Polymers of sugars Function: costs little energy to build easily reversible = release energy Function: energy storage starch (plants) glycogen (animals) in liver & muscles structure cellulose (plants) chitin (arthropods & fungi) Polysaccharides are polymers of hundreds to thousands of monosaccharides

Long term energy storage… Lipids Long term energy storage…

Lipids Lipids are composed of C, H, O “Family groups” long hydrocarbon chains (H-C) “Family groups” fats phospholipids steroids Do not form polymers big molecules made of smaller subunits not a continuing chain Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties

Fats store energy Long HC chain Function: polar or non-polar? hydrophilic or hydrophobic? Function: energy storage concentrated all H-C! 2x carbohydrates cushion organs insulates body What happens when you add oil to water Why is there a lot of energy stored in fats? • big molecule • lots of bonds of stored energy So why are we attracted to eating fat? Think about our ancestors on the Serengeti Plain & during the Ice Age. Was eating fat an advantage?

Phospholipids Hydrophobic or hydrophilic? fatty acid tails = PO4 head = split “personality” hydrophobic hydrophillic “attracted to water” “repelled by water”

Steroids Structure: 4 fused C rings + ?? different steroids created by attaching different functional groups to rings different structure creates different function examples: cholesterol, sex hormones cholesterol

Multipurpose molecules Proteins Multipurpose molecules clockwise: Rubisco — most important protein on the planet? Hemoglobin — a red blooded protein :-) Collagen — strings you together Growth Hormones — working hard in you right now! 2008-2009

Proteins Most structurally & functionally diverse group Function: involved in almost everything enzymes (pepsin, DNA polymerase) structure (keratin, collagen) carriers & transport (hemoglobin, aquaporin) cell communication signals (insulin & other hormones) receptors defense (antibodies) movement (actin & myosin) storage (bean seed proteins) Storage: beans (seed proteins) Movement: muscle fibers Cell surface proteins: labels that ID cell as self vs. foreign Antibodies: recognize the labels ENZYMES!!!!

Proteins Structure monomer = amino acids polymer = polypeptide H2O Structure monomer = amino acids 20 different amino acids polymer = polypeptide protein can be one or more polypeptide chains folded & bonded together large & complex molecules complex 3-D shape Rubisco = 16 polypeptide chains Hemoglobin = 4 polypeptide chains (2 alpha, 2 beta) hemoglobin Rubisco growth hormones

Amino acids H O | H || —C— C—OH —N— R Structure central carbon amino group carboxyl group (acid) R group (side chain) variable group different for each amino acid confers unique chemical properties to each amino acid like 20 different letters of an alphabet can make many words (proteins) —N— H R

dehydration synthesis Building proteins Peptide bonds covalent bond between NH2 (amine) of one amino acid & COOH (carboxyl) of another C–N bond H2O dehydration synthesis free COOH group on one end is ready to form another peptide bond so they “grow” in one direction from N-terminal to C-terminal peptide bond

Building proteins Polypeptide chains have direction N-terminus = NH2 end C-terminus = COOH end repeated sequence (N-C-C) is the polypeptide backbone can only grow in one direction

Primary (1°) structure Order of amino acids in chain amino acid sequence determined by gene (DNA) slight change in amino acid sequence can affect protein’s structure & its function even just one amino acid change can make all the difference! Sickle cell anemia: 1 DNA letter changes 1 amino acid = serious disease Hemoglobin mutation: bends red blood cells out of shape & they clog your veins. lysozyme: enzyme in tears & mucus that kills bacteria

Secondary (2°) structure “Local folding” folding along short sections of polypeptide interactions between adjacent amino acids H bonds weak bonds between R groups forms sections of 3-D structure -helix -pleated sheet It’s a helix or B sheet within a single region. Can have both in one protein but a specific region is one or another

Tertiary (3°) structure “Whole molecule folding” interactions between distant amino acids hydrophobic interactions cytoplasm is water-based nonpolar amino acids cluster away from water H bonds & ionic bonds disulfide bridges covalent bonds between sulfurs in sulfhydryls (S–H) anchors 3-D shape How the whole thing holds together

Quaternary (4°) structure More than one polypeptide chain bonded together only then does polypeptide become functional protein hydrophobic interactions Structure equals function wonderfully illustrated by proteins Collagen is just like rope -- enables your skin to be strong and flexible. hemoglobin collagen = skin & tendons

Protein denaturation Unfolding a protein conditions that disrupt H bonds, ionic bonds, disulfide bridges temperature pH salinity alter 2° & 3° structure alter 3-D shape destroys functionality some proteins can return to their functional shape after denaturation, many cannot

Nucleic Acids Information storage 2006-2007

Nucleic Acids Examples: Structure: RNA (ribonucleic acid) single helix DNA (deoxyribonucleic acid) double helix Structure: monomers = nucleotides DNA RNA

Nucleotides 3 parts nitrogen base (C-N ring) pentose sugar (5C) ribose in RNA deoxyribose in DNA phosphate (PO4) group DNA & RNA are negatively charged: Don’t cross membranes. Contain DNA within nucleus Need help transporting mRNA across nuclear envelope. Also use this property in gel electrophoresis.

Types of nucleotides 2 types of nucleotides different nitrogen bases purines double ring N base adenine (A) guanine (G) pyrimidines single ring N base cytosine (C) thymine (T) uracil (U)

5. 1) Which term includes all others in the list 5.1) Which term includes all others in the list? A) monosaccharide B) polysaccharide C) carbohydrate D) disaccharide

5. 1) Which term includes all others in the list 5.1) Which term includes all others in the list? A) monosaccharide B) polysaccharide C) carbohydrate D) disaccharide

5. 2) Which of the following is not a protein 5.2) Which of the following is not a protein? A) cholesterol B) an enzyme C) insulin D) hemoglobin

5. 2) Which of the following is not a protein 5.2) Which of the following is not a protein? A) cholesterol B) an enzyme C) insulin D) hemoglobin

5.3) Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes? A) The purines would be separated from the deoxyribose sugars. B) All bases would be separated from the deoxyribose sugars. C) The phosphodiester bonds between deoxyribose sugars would be broken. D) The two strands of the double helix would separate. E) The pyrimidines would be separated from the deoxyribose sugars.

5.3) Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes? A) The purines would be separated from the deoxyribose sugars. B) All bases would be separated from the deoxyribose sugars. C) The phosphodiester bonds between deoxyribose sugars would be broken. D) The two strands of the double helix would separate. E) The pyrimidines would be separated from the deoxyribose sugars.

5.4) Which of the following statements concerning unsaturated fats is true? A) They contain more hydrogen than saturated fats having the same number of carbon atoms. B) They are more common in animals than in plants. C) They have fewer fatty acid molecules per fat molecule. D) They have double bonds in the carbon chains of their fatty acids. E) They generally solidify at room temperature.

5.4) Which of the following statements concerning unsaturated fats is true? A) They contain more hydrogen than saturated fats having the same number of carbon atoms. B) They are more common in animals than in plants. C) They have fewer fatty acid molecules per fat molecule. D) They have double bonds in the carbon chains of their fatty acids. E) They generally solidify at room temperature.

5.5) The structural level of a protein least affected by a disruption in hydrogen bonding is the A) tertiary level. B) primary level. C) secondary level. D) quaternary level.

5.5) The structural level of a protein least affected by a disruption in hydrogen bonding is the A) tertiary level. B) primary level. C) secondary level. D) quaternary level.

Practice FRQ – Macromolecules

Practice FRQ – Macromolecules (10 points)