Unit 1: Cellular Energetics

1. Unit 1: Cellular Energetics • Part I – Macromolecules • Part II – Enzymes • Part III – Cellular Respiration • Part IV – DNA Replication • Part V – Protein Synthesis

2. Part I – Macromolecules

3. The questions: • What are monomers? What are polymers? • How are polymers synthesized (built) and hydrolyzed (broken down)?

4. Dehydration Synthesis (condensation) • Reaction that joins molecules together by removing water • Polymerization = the synthesis of a polymer • Polymers are built from monomers via dehydration synthesis

5. Hydrolysis • Breaks polymers into their constituent monomers (“building blocks”) by lysing (breaking) bonds through the addition of water.

6. 1. Carbohydrates (polysaccharides) • Contain CHO • General molecular formula = CH2O • Aldoses and Ketoses vary in location of carbonyl group -C=O • Aldoses have carbonyl on ends (glucose) • Ketoses have carbonyl within molecule (fructose)

7. Monomer = monosaccharide

8. Disaccharides (double sugars) • 2 monosaccharides joined by a glycosidic linkage • Covalent bond formed between two monosaccharides by dehydration synthesis

9. Examples of disaccharides • Maltose = glucose + glucose • Sucrose = glucose + fructose • Lactose = glucose + galactose

10. Polysaccharides (many sugars) • Long polymers of many monosaccharides • Architecture & function determined by position of glycosidic linkages • Alpha linkages are breakable by Eukaryotes • Starch, glycogen • Beta linkages are NOT • Cellulose, chitin

12. Types of Polysaccharides • A. Structural polysaccharides: • Beta glycosidic linkages • Cellulose - plant cell walls, structural molecule • Chitin - exoskeleton in insects, arachnids, crustaceans

13. B. Food storage molecules • Alpha glycosidic linkages • Starch- food storage molecules in plants • Glycogen- food storage molecules in animals

14. 2. Lipids • Group shares one common trait – no affinity for water • Do NOT consist of monomers → polymers • Highly varied group • Biologically important: • Fats • Phospholipids • Steriods

15. A. Fats • Made of glycerol and 3 fatty acids • Saturated fatty acids (animal fats) are carbon chains with single bonds only • Ex: Butter, lard; solids at room temp. • Unsaturated fatty acids (plant fats) have at least one double bond (kinks in chain) • Monounsaturated = only one double bond • Polyunsaturated = many double bonds • Ex: Vegetable oils; liquid at room temp

16. “Hydrogenated” fatty acids • Hydrogen is artificially added to replace double bonds with single bonds. • Liquids are solidified • Ex: peanut butter, margarine

18. B. Phospholipids • 2 fatty acids (tails) attached to phosphate group “head” • When placed in water they self assemble into a micelle

20. C. Steroids • Lipids characterized by carbon skeletons consisting of four fused rings • Ex. Cholesterol • Common component of animal cell membranes (this is why animal meat is higher in cholesterol) • Precursor from which other steroids, including sex hormones, are synthesized

22. 3. Proteins • Most diverse of all macromolecules • Humans have over twenty thousand proteins in their bodies, each performing a specific function

23. General Categories of Proteins • 1) Structural: Spider silk • 2) Storage : Egg white • 3) Transport: Hemoglobin • 4) Hormonal: Insulin • 5) Receptor: Transport protein • 6) Contractile: Actin & myosin • 7) Defensive: Antibodies • 8) Enzymatic: Digestive enzymes

24. Monomers = Amino Acids • 20 total amino acids • 8 “essential” AA’s; must be derived from food • 12 can be synthesized by body • THREE TYPES • Non-polar (8) • Polar (7) • Electrically charged (acidic, basic) (5)

25. General structure of amino acid • All amino acids have a carboxyl group (-COOH) on one end and an amino group (NH3) on the other • R group determines their interactions with one another to form secondary, tertiary, and quaternary structure

27. Polymers = polypeptides • Formed by dehydration synthesis • Peptide bonds: bonds between adjacent amino acids

28. Protein shape determines function • Primary structure: sequence of amino acids

29. Secondary Structure: coiling or folding of polypeptide chain in repeated patterns • Ex: Alpha helices • Ex: Beta pleated sheets

30. Tertiary structure: irregular contortions from interactions between side chains (R-groups) with one another • H-bonds • Disulfide bridges • Hydrophobic interactions

31. Quaternary structure: 2 or more polypeptide chains aggregated into 1 functional molecule

33. 4. Nucleic Acids • Nucleic acids are the building blocks of both DNA and RNA • DNA directs its own replication, transmits genetic information to future offspring, and controls RNA synthesis • RNA controls protein synthesis

34. Nucleotides

35. Monomer = Nucleotides • Nucleotide - building block of nucleic acids • Composed of three subunits: • 1) Pentose sugar (ribose or deoxyribose) • 2) Phosphate groups comprise the “sugar-phosphate” backbone • 3) Nitrogenous bases = variable portions of the molecule

36. DNA vs. RNA

37. Polymer = polynucleotide • Adjacent nucleotides are joined by covalent bonds called phosphodiester linkages between the -OH on one nucleotide and the phosphate on the next nucleotide

39. Complementary Base Pairing • Always a Pyrimidine with a Purine • Purines are Adenine & Guanine • Pyrimidines areCytosine, Thymine (DNA only), and Uracil (RNA only)

41. Complementary Base Pairing

42. Why Do Bases Bond This Way? • Hydrogen bonds: • A and T form two hydrogen bonds • G and C form three hydrogen bonds • Therefore, there is no way to bond inappropriately

43. Base Pairing T A

44. Base Pairing C G

45. Macro Structure of DNA • Double Helix- “Twisted Ladder” of A-T and G-C base pairing • DNA contains genes(thousands) that code for proteins • In association with proteins (histones) DNA makes chromosomes (46 in humans) • Stored in nuclei of Eukaryotic cells