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Chapter 3

Chapter 3. The Molecules of Cells. Organic compounds. Always contain carbon Always have covalent bonds (not ionic) Usually associated with large numbers of atoms Commonly associated with living things. carbon. Can covalently bond with as many as 4 other atoms 4 valence electrons

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Chapter 3

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  1. Chapter 3 The Molecules of Cells

  2. Organic compounds • Always contain carbon • Always have covalent bonds (not ionic) • Usually associated with large numbers of atoms • Commonly associated with living things

  3. carbon • Can covalently bond with as many as 4 other atoms • 4 valence electrons • Can form many shapes • 3-Dimensional shape is very important to function

  4. Carbon compounds

  5. Carbon Compounds • Carbohydrates • Lipids • Proteins • Nucleic Acids

  6. Building compounds • Monomer—individual building unit • Carbohydrates—monosaccharides • Lipids—fatty acids • Proteins—amino acids • Nucleic acids—nucleotides • Polymer—many units covalently bonded • Each monomer is like a pearl on a necklace

  7. Building compounds • Functional groups—atoms or clusters of atoms covalently bonded to organic compounds that affect the compound’s structure and function

  8. Reaction categories • Fuctional-group transfer • Changes the chemical reactivity • Electron transfer • Transfers energy • Rearrangement • Changes internal bonds, changing 3D structure • Condensation • Combines two compounds by removing water • Dehydration synthesis • Cleavage • Splits compounds with water • Hydrolysis

  9. condensation • Split OH- from one molecule • Split H+ from another molecule • Bonds form at exposed sites • Water is byproduct • “Dehydration Synthesis”—Remove water (dehydrate) to combine/create (synthesize)

  10. hydrolysis • Reverse of condensation • Split molecules • Add OH- and H+ from water • Literally “water splitting” • Hydro = water • Lysis = break, destroy

  11. carbohydrates • Contain C, H, and O in 1:2:1 ratio • Hydrophilic • Used for energy storage, structure

  12. carbohydrates • Monosaccharides • Single sugar unit • Glucose, fructose, galactose • Hydroxyl group (OH-) • Isomers—same molecular formula (C6H12O6), different structure • Used to assemble larger carbohydrates

  13. carbohydrates • Disaccharide • Short chain of two sugar monomers • Formed by dehydration synthesis • Maltose—Glucose + Glucose • Sucrose—Glucose + Fructose • Lactose—Glucose + Galactose

  14. carbohydrates • Polysaccharide—chain of hundreds or thousands of monomers • Straight or branched • “Complex” carbohydrates • Starch—plant energy storage • Easily converted to glucose • Slightly- or unbranched • Cellulose—plant structural • Cell wall • Insoluble in water, indigestible • Glycogen—animal energy storage • Stored in muscle & liver • Highly branched • Chitin—structural component of insects

  15. lipids • Greasy or oily compounds • Non-polar, hydrophobic • Energy storage, membrane structure, coatings, insulation

  16. Lipids • Fatty acids—long chain of mostly C and H with a carboxyl group (-COOH) at the end • Saturated—single Carbon bonds • “Saturated” with hydrogen (H+ everywhere possible) • Unsaturated—double Carbon bonds • Some carbons don’t have max possible H+

  17. Lipids

  18. Lipids • Fat—one or more fatty acids attached to glycerol • Twice the energy of carbohydrates • Triglycerides—95% of all fats • Glycerol + 3 Fatty Acid side chains • Combined through dehydration synthesis

  19. Lipids • Phospolipid • 2 Fatty Acids + Phosphate Group + Glycerol • Similar to triglyceride but with phosphate group replacing a fatty acid chain • Main structural material of membranes • Hydrophilic “head”, hydrophobic “tail”

  20. lipids • Sterols • 4 carbon rings, no fatty acid tails • Cholesterol, testosterone, estrogen, other hormones • Some regulate vitamin D function • Regulate cell membrane fluidity

  21. lipids • Waxes • Long-chain fatty acids + alcohols or carbon rings • Coatings for plant parts or animal coverings

  22. Proteins • Most diverse of all biological molecules • Enzymes • Cell movement • Cell signaling • Storage & transport • Hormones • Antibodies • Structure

  23. proteins • Amino acid—monomer unit • Three groups covalently bonded to central C • Same backbone, vary only in R group • 20 amino acids necessary for life

  24. proteins • Polypeptides—polymer of proteins • Peptide bond, between C and N • Formed by dehydration synthesis

  25. Proteins • Structure • Primary • Secondary • b Pleated Sheet • Alpha Helix • Tertiary • Quaternary • The shape of the structure determines function • Shape is determined by amino acids & hydrogen bonds • A single amino acid change will affect all the way to the quaternary structure

  26. Proteins • Why is structure important? • Change in shape is VERY important to function • Sickle cell anemia due to a single amino acid difference • Denaturation—unraveling of polypeptide chains • Loose shape, therefore also function

  27. proteins • Lipoproteins • Bonded to fats • Glycoproteins • Bonded to carbohydrates

  28. Nucleic acids • Important to metabolism & heredity • Nucleotide—monomer unit • 5-carbon sugar (ribose or deoxyribose) • Nitrogen base • Adenine, thymine, guanine, cytosine, uracil • Phosphate group

  29. Nucleic acid • DNA—double-stranded helix, carries hereditary information • RNA—single-stranded helix, translates code to build proteins • ATP—single nucleotide, releases energy for cells to work

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