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Ch. 5 Structure and Function of Macromolecules

Explore the structure and function of macromolecules in biology, including carbohydrates, lipids, proteins, and nucleic acids. Learn about the formation of polymers and the unique properties of different macromolecules.

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Ch. 5 Structure and Function of Macromolecules

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  1. Ch. 5 Structure and Function of Macromolecules AP Biology

  2. Macromolecules • Most are polymers • Polymer • Large molecule consisting of many identical or similar building blocks linked by bonds • Monomer • Subunits that serve as building blocks for polymers Polyethene is a thermoplastic commodity heavily used in consumer products (over 60 million tons are produced worldwide every year).

  3. A limitless variety of polymers can be built from a small set of monomers • Inherent differences between siblings result from variations in polymers • Construction of macromolecules • 40-50 common monomers and others that occur rarely • Small molecules that are common to all organisms are ordered into unique macromolecules

  4. How Cells Use Organic Compounds • Biological organisms use the same kinds of building blocks. • All macromolecules (large, complex molecules) have specific functions in cells. • Other than water, macromolecules make up the largest percent mass of a cell.

  5. Condensation and Hydrolysis • Condensation reactions • Dehydration reactions • When two molecules become covalently bonded to each other through the loss of a small molecule, usually water • Hydrolysis • Separation of two molecules by the addition of a water molecule

  6. The Molecules of Life • Large polymers form from smaller monomers. • New properties emerge. • Living cells require/synthesize: • Carbohydrates • Lipids • Proteins • Nucleic Acids

  7. Carbohydrates • Used as fuel and building material • Carbs are sugars and their polymers • Main types: • Monosaccharides • Disaccharides • Polysaccharides

  8. Monosaccharides (CH2O) • Generally have molecular formulas in some multiple of CH2O • Glucose (C6H12O6) is most common • In aqueous solution may form rings • Major nutrients for cells

  9. Disaccharides • Two monosaccharides joined by glycosidic linkages • Glycosidic linkage • A covalent bond formed between monosaccharides • Sucrose is most prevalent

  10. Dissacharide Formation

  11. Polysaccharides • 100s to 1000s of monosaccharides long • Starch • Storage poly. of plants • Glycogen • Storage poly. of animals • Cellulose • Structural poly. which is a major component of tough plant cell walls • Chitin • Structural poly. used by arthropods to build exoskeletons

  12. Starch & Cellulose Forms ring in aqueous solution

  13. Lipids • Mostly hydrophobic molecules with diverse functions • Little or no affinity for water • Used for energy storage and structure • Main types: • Fats • Phospholipids • Steroids

  14. Fats • Large molecules, but not polymers • Fatty acid • A long carbon skeleton with carboxyl group head and a hydrocarbon tail 14

  15. Triacylglycerol (Triglyceride) • Three fatty acids linked to one glycerol molecule

  16. Saturated & Unsaturated Fats • Saturated fatty acids • Fatty acid containing no double bonds between the carbon atoms composing the tail • Solids at room temp. • Unsaturated fatty acids • Has one or more double bonded carbons in the tail

  17. Phospholipids • Two fatty acid tails linked to one glycerol molecule • Ambivalent behavior toward water • When in contact with water they form a micelle (cluster)

  18. Steroids • Lipids characterized by a carbon skeleton, consisting of 4 interconnected rings • Cholesterol • Important steroid that is a common component of the membranes of animal cells • Many hormones are steroids produced from cholesterol

  19. Proteins • The molecular tools for most cellular functions • Used for: • Structural support • Storage • Transport of other substances • Signaling from one part of the organism to the other • Movement • Defense against foreign substances • Conformation • Unique 3-D shape of a protein

  20. Protein Polypeptides • Polymers of amino acids connected in a specific sequence • Amino acids • Organic molecules possessing both carboxyl and amino groups • Acidity is determined by side chains 20

  21. Peptide Bonds • Formed when an enzyme joins amino acids by means of condensation • Polypeptide • Chains of amino acids linked by peptide bonds

  22. Protein Conformation • Conformation (shape) determines function and is the result of the linear sequence of amino acids in a polypeptide. • Folding, coiling and the interactions of multiple polypeptide chains create a functional protein • 4 levels of conformation • Primary • Secondary • Tertiary • Quartinary

  23. Primary Structure • Unique, linear sequence of amino acids in a protein • A change in one a.a. can effect every other level of structure • ex. point mutation in hemoglobin

  24. Secondary Structure • Hydrogen bonding occurs between amino and carbonyl groups of amino acids. • Structures Formed: • αHelix: Common in fibrous proteins, creates “elastic” properties. • βSheet: Anti-parallel chains form sheet.

  25. Tertiary Structure • Irregular contortions from bonding between side chains of various amino acids 25

  26. Quartinary Structure • Overall protein structure that results from aggregation of tertiary subunits

  27. Denaturation • Unraveling and loss of native conformation of a protein • Can be due to heat, pH, salts, etc. • Some can renature exactly, others cannot • Ex: cooking an egg

  28. Nucleic Acids • Store and transmit hereditary information • Gene • A unit of inheritance • DNA & RNA • Deoxyribonucleic acid & Ribonucleic acid • DNA is like computer software, proteins are like hardware • Genetic info flows from DNA  RNA  protein

  29. DNA Structure • A polymer with an information-rich sequence of nucleotides • Pyrimidine • 6 membered ring made of carbon and nitrogen atoms • Cytosine and thymine • Purine • 6 membered ring fused to a five membered ring • Adenine and guanine • Phosphodiester • Covelent bonds holding nucleotides together

  30. DNA Structure, cont. • Double helix • Two chains of nucleotides that spiral around an imaginary axis • Hydrogen bonds • Hold two chains of nucleotides together • Adenine pairs with thymine • Cytosine pairs with guanine • Two strands of DNA double helix are complimentary

  31. RNA • Single stranded • Four kinds of nucleotide monomers (A, U, C, G) • Key players in the protein-building processes • mRNA, tRNA, rRNA

  32. DNA & Protein Importance • Inheritance is based on precise replication of DNA • We can use DNA and proteins as “tape measures” of evolution • Linear sequences of nucleotides in DNA molecules are passed from parents to offspring • More distantly related species have chains that are less similar

  33. Review questions • Section 4.1 page 59, number 1 • Read Inquiry 4.2. Think about the what if question. • Section 5.1 page 69, number 1 • Section 5.2 page 74, number 3 • Self quiz page 91 numbers 1-8.

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