The Structure and Function of Macromolecules

1. The Structure and Function of Macromolecules

2. I. Polymers • What is a polymer? • Poly = many; mer = part. A polymer is a large molecule consisting of many smaller sub-units bonded together. • What is a monomer? • A monomer is a sub-unit of a polymer.

3. A. Making and Breaking Polymers • How are covalent linkages between monomers formed in the creation of organic polymers? • Condensation or dehydration synthesis reactions. • Monomers are covalently linked to one another through the removal of water.

4. Condensation Synthesis

5. Hydrolysis • What is a hydrolysis reaction? • Polymers are broken down into monomers. • Hydro = water; lysis = loosening/ • Water is added and the lysis of the polymer occurs.

6. Hydrolysis

7. II. Classes of Organic Molecules: • What are the four classes of organic molecules? • Carbohydrates • Lipids • Proteins • Nucleic Acids

8. A. Carbohydrates • Sugars • Carbo = carbon, hydrate = water; carbohydrates have the molecular formula (CH2O)n • Functions: • Store energy in chemical bonds • Glucose is the most common monosaccharide • Glucose is produced by photosynthetic autotrophs

9. 1. Structure of Monosaccharides • An OH group is attached to each carbon except one, which is double bonded to an oxygen (carbonyl).

10. Triose = 3 carbons Pentose = 5 carbons Hexose = 6 carbons • Classified according to the size of their carbon chains, varies from 3 to 7 carbons.

11. In aqueous solutions many monosaccharides form rings:

12. 2. Structure of Disaccharides • Double sugar that consists of 2 monosaccharides, joined by a glycosidic linkage. • What reaction forms the glycosidic linkage? • Condensation synthesis

13. Examples of Disaccharides: Sucrose = glucose + fructose Lactose = glucose + galactose

14. 3. Polysaccharides • Structure: Polymers of a few hundred or a few thousand monosaccharides. • Functions: energy storage molecules or for structural support:

15. Starch is a plant storage from of energy, easily hydrolyzed to glucose units • Cellulose is a fiber-like structureal material - tough and insoluble - used in plant cell walls • Glycogen is a highly branched chain used by animals to store energy in muscles and the liver. • Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls.

16. B. Lipids • Structure: Greasy or oily nonpolar compounds • Functions: • Energy storage • membrane structure • Protecting against desiccation (drying out). • Insulating against cold. • Absorbing shocks. • Regulating cell activities by hormone actions.

17. 1. Structure of Fatty Acids • Long chains of mostly carbon and hydrogen atoms with a -COOH group at one end. • When they are part of lipids, the fatty acids resemble long flexible tails.

18. Saturated and Unsaturated Fats • Unsaturated fats : • liquid at room temp • one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails • most plant fats • Saturated fats: • have only single C-C bonds in fatty acid tails • solid at room temp • most animal fats

20. Saturated fatty acid

21. Saturated fatty acid Unsaturated fatty acid

22. 2. Structure of Triglycerides • Glycerol + 3 fatty acids • 3 ester linkages are formed between a hydroxyl group of the glycerol and a carboxyl group of the fatty acid.

23. 3. Phospholipids • Structure: Glycerol + 2 fatty acids + phosphate group. • Function: Main structural component of membranes, where they arrange in bilayers.

24. Phospholipids in Water

25. 4. Waxes • Function: • Lipids that serve as coatings for plant parts and as animal coverings.

26. 5. Steroids • Structure: Four carbon rings with no fatty acid tails • Functions: • Component of animal cell membranes • Modified to form sex hormones

27. C. Proteins • Structure: • Polypeptide chains • Consist of peptide bonds between 20 possible amino acid monomers • Have a 3 dimensional globular shape

28. 1. Functions of Proteins • Enzymes which accelerate specific chemical reactions up to 10 billion times faster than they would spontaneously occur. • Structural materials, including keratin (the protein found in hair and nails) and collagen (the protein found in connective tissue).

29. Specific binding, such as antibodies that bind specifically to foreign substances to identify them to the body's immune system. • Specific carriers, including membrane transport proteins that move substances across cell membranes, and blood proteins, such as hemoglobin, that carry oxygen, iron, and other substances through the body.

30. Contraction, such as actin and myosin fibers that interact in muscle tissue. • Signaling, including hormones such as insulin that regulate sugar levels in blood.

31. 2. Structure of Amino Acid Monomers • Consist of an asymmetric carbon covalently bonded to: • Hydrogen • Amino group • Carboxyl (acid) group • Variable R group specific to each amino acid

32. Properties of Amino Acids • Grouped by polarity • Variable R groups (side chains) confer different properties to each amino acid: • polar, water soluble. • non-polar, water insoluble • positively charged • negatively charged.

33. 4 levels of protein structure: • primary • secondary • tertiary • quaternary

34. 3. Primary Structure • Unique sequence of amino acids in a protein • Slight change in primary structure can alter function • Determined by genes • Condensation synthesis reactions form the peptide bonds between amino acids

36. 4. Secondary Structure • Repeated folding of protein’s polypeptide backbone • stabilized by H bonds between peptide linkages in the protein’s backbone • 2 types, alpha helix, beta pleated sheets

38. 5. Tertiary Structure • Irregular contortions of a protein due to bonding between R groups • Weak bonds: • H bonding between polar side chains • ionic bonding between charged side chains • hydrophobic and van der Waals interactions • Strong bonds: • disulfide bridges form strong covalent linkages

40. 5. Quaternary Structure • Results from interactions among 2 or more polypeptides

42. Factors That Determine Protein Conformation • Occurs during protein synthesis within cell • Depends on physical conditions of environment • pH, temperature, salinity, etc. • Change in environment may lead to denaturation of protein • Denatured protein is biologically inactive • Can renature if primary structure is not lost

43. D. Nucleic Acids • Two kinds: • DNA: double stranded can self replicate makes up genes which code for proteins is passed from one generation to another • RNA: single stranded functions in actual synthesis of proteins coded for by DNA is made from the DNA template molecule

45. 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

47. 2. Building the Polymer • Phosphate group of one nucleotide forms strong covalent bond with the #3 carbon of the sugar of the other nucleotide.

48. 3. Functions of Nucleotides • Monomers for Nucleic Acids • Transfer chemical energy from one molecule to another (e.g. ATP)

49. DNA: • Double helix • 2 polynucleotide chains wound into the double helix • Base pairing between chains with H bonds • A - T • C - G

50. Summary of the Organic Molecules: