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Marvelous Macromolecules

Marvelous Macromolecules. Chapter 5. Macromolecules. Large molecules formed by joining smaller organic molecules Four Major Classes Carbohydrates Lipids Proteins Nucleic Acids. Polymers. Many similar or identical building blocks linked by covalent bonds. Monomers.

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Marvelous Macromolecules

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  1. Marvelous Macromolecules Chapter 5

  2. Macromolecules • Large molecules formed by joining smaller organic molecules • Four Major Classes • Carbohydrates • Lipids • Proteins • Nucleic Acids

  3. Polymers • Many similar or identical building blocks linked by covalent bonds

  4. Monomers • Small units that join together to make polymers • Connected by covalent bonds using a condensation (dehydration) reaction • One monomer gives a hydroxyl group, the other gives a hydrogen to form water • Process requires ENERGY and ENZYMES

  5. Let’s Get Together…Yah, Yah, Yah

  6. Breakdown • Polymers are disassembled by hydrolysis • The covalent bond between the monomers is broken splitting the hydrogen atom from the hydroxyl group • Example – digestion breaks down polymers in your food into monomers your body can use

  7. Breakin’ Up is Hard to Do…

  8. Variety • Each cell has thousands of different macromolecules • These vary among cells of the same individual; they vary more among unrelated individuals in the same species; and vary even more in different species • 40 to 50 monomers combine to make the huge variety of polymers

  9. Carbohydrates • Used for fuel (energy) and building material • Includes sugars and their polymers • Monosaccharides – simple sugars • Disaccharides – double sugars (two monosaccharides joined by condensation reaction • Polysaccharides – polymers of monosaccharides (many sugars joined together)

  10. Monosaccharides • Molecular formula is usually a multiple of CH2O • Ex – Glucose C6H12O6

  11. Classification of Monosaccharides • ALWAYS HAVE A CARBONYL GRP. and HYDROXYL GRPS. • Location of carbonyl group • If carbonyl is on end – aldose • If carbonyl is in middle – ketose • Number of carbons in backbone • Six carbons – hexose • Five carbons - pentose • Three carbons - triose

  12. Characteristics of Monosaccharides • Major fuel for cellular work – especially glucose – makes ATP • In aqueous solutions – form rings • Joined by glycosidic linkage through a dehydration reaction

  13. Disaccharides • Two monosaccharides joined together with a glycosidic linkage • Maltose – formed when 2 glucose molecules are joined • Sucrose (table sugar) formed by joining glucose and fructose • Used to transport sugar in plants

  14. Polysaccharides • Polymers of sugar • Can be hundreds to thousands of monosaccharides joined together by glycosidic linkages • Used in energy storage then broken down as needed in the cell • Also used to maintain structure in cells

  15. Examples of Polysaccharides • Starch – storage polysaccharide made entirely of glucose monomers • Plants store starch in plastids • Plants can use glucose stored in starch when they need energy or carbon • When animals eat plants, they use the starch as an energy source • Made of ALPHA glucose rings

  16. Examples of Polysaccharides • Cellulose • Polymer of glucose monomers • Made of BETA glucose rings • Found in Cell Walls of plants (very tough) • Animals can’t digest cellulose (passes through making digestion easier) • Herbivores have special microbes in their stomachs that can digest cellulose (that’s why they can survive on only plants)

  17. Examples of Polysaccharides • Glycogen – polysaccharide of glucose used for sugar storage in ANIMALS • Humans and vertebrates store glycogen in liver and muscles

  18. Examples of Polysaccharides • Chitin • Structural polysaccharide • Used in exoskeletons of arthropods (insects, spiders, crustaceans) • Forms the structural support for cell walls of fungi I crunch when I get stepped on because of Chitin

  19. Lipids  • Hydrophobic molecules • Nonpolar bonds making them have little or no affinity for water • Store large amounts of energy • Not “polymers”, but are large molecules made from smaller ones

  20. Fats • Made of glycerol (3 Carbons with hydroxyl attached) and 3 fatty acids (long carbon skeleton) • Joined by ester linkage in dehydration reaction • Used in energy storage, cushion organs, and for insulation

  21. Saturated Fats • Fatty acids with no carbon-carbon double bonds • Pack tightly together making SOLIDS at room temperature • Most animal fats are saturated • Eating too much can block arteries

  22. Unsaturated Fats • Fatty acid has one or more carbon-carbon double bonds • Kinks from double bonds prevent tight packing • Liquid at room temperature • Plant and fish fats - oils

  23. Phospholipids • Glycerol joins with 2 fatty acids and 1 phosphate group • Phosphate group carries negative charge making heads that are hydrophilic • Fatty acids are nonpolar, making tails that are hydrophobic • Major components of cell membranes – phospholipid bilayer

  24. Steroids • Carbon skeleton with four fused carbon rings • Functional groups attached to rings make different steroids • Cholesterol – used in animal cell membranes • Precursor for all other steroids • Many hormones are steroids

  25. Proteins • Function in • Storage • Transport • Intercellular signals • Movement • Defense • Structural Support • Speeding up reactions (enzymes)

  26. Polypeptide • Polymer of amino acids (monomer) joined by peptide bonds • One or more polypeptides come together to make protein • Each protein has complex 3-D shape Amino Acid Amino Acid Amino Acid

  27. Amino Acids • Made of • Hydrogen • Carboxyl group • Amino group • R-group – varies from one amino acid to the next • 20 amino acid monomers make thousands of proteins • Joined together by dehydration reaction that removes hydroxyl group from one and amino group of another to make a peptide bond

  28. Structure determines function • Polypeptides must be folded into a unique shape before becoming proteins • Order of amino acids determines shape • Shape of protein determines its function • Ex. – antibodies bind to foreign substances based on shape • Folding occurs spontaneously

  29. Levels of Protein Structure • Primary – determined by unique sequence of amino acids • Order of amino acids comes from DNA • Changing primary structure can change the shape of a protein and could cause it to be inactive • Ex – sickle cell caused by one amino acid change

  30. Levels of Protein Structure • Secondary – comes from hydrogen bonds at regular intervals along the polypeptide backbone • Alpha helix – coils • Beta pleated sheets - folds

  31. Levels of Protein Structure • Tertiary – determined by interactions among R-groups on amino acids • Hydrogen bonds • Hydrophobic/hydrophilic interactions • Van der Waals interactions • Ionic bonds (charged R groups) • Disulfide bridges between sulfhydryl groups of cysteine amino acids (stabilize structure)

  32. Levels of Protein Structure • Quaternary – occurs with two or more polypeptide subunits • Collagen – three polypeptides coiled like a rope – good for structure • Hemoglobin – four polypeptide (two different types) – carries oxygen

  33. Changing Protein Structure • Physical and Chemical conditions can change the shape of a protein • pH • Salt concentration • Temperature • Others • Changes can disrupt secondary or tertiary structures • Some proteins can return to original shape, but others are permanently denatured

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