Ch. 5 Structure and Function of Macromolecules

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

28. 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

29. 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

30. 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

31. 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

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

33. 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

34. 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.