Chapter 5. Macromolecules. AP Biology

Transcription

1 Chapter 5. Macromolecules

2 Macromolecules Smaller organic molecules join together to form larger molecules macromolecules 4 major classes of macromolecules: carbohydrates lipids proteins nucleic acids

3 Polymers Long molecules built by linking chain of repeating smaller units polymers monomers = repeated small units covalent bonds

4 How to build a polymer Condensation reaction dehydration synthesis joins monomers by taking H 2 O out 1 monomer provides OH the other monomer provides H together these form H 2 O requires energy & enzymes

5 How to break down a polymer Hydrolysis use H 2 O to break apart monomers reverse of condensation reaction H 2 O is split into H and OH H & OH group attach where the covalent bond used to be ex: digestion is hydrolysis

6 Carbohydrates

7 Carbohydrates Carbohydrates are composed of C, H, O carbo - hydr - ate Function: CH 2 O (CH 2 O) x C 6 H 12 O 6 1. energy 2. energy storage 3. raw materials 3. structural materials Monomer: monosaccharides (sugars) Polymer: polysaccharide

8 Carbohydrates include Sugars Most names for sugars end in -ose Classified by number of carbons 6C = hexose (glucose) 5C = pentose (fructose, ribose) 3C = triose (glyceraldehyde)

9 What functional groups? carbonyl aldehyde ketone hydroxyl

10 Sugar structure 5C & 6C sugars form rings in aqueous solutions in cells! Carbons are numbered

11 Numbered carbons 5' C C 6' O 4' C C 1' C 3' C 2'

12 Simple & complex sugars Monosaccharides (simple) simple 1 monomer sugars glucose Disaccharides (simple) 2 monomers sucrose Polysaccharides (complex) large polymers starch

13 Building sugars Dehydration synthesis monosaccharides disaccharide glucose glucose maltose glycosidic linkage

14 Other examples: Sucrose = glucose + fructose Maltose = glucose + glucose Lactose = glucose + galactose

15 Polysaccharides Polymers of sugars costs little energy to build easily reversible = release energy Function: 1. energy storage starch (plants) glycogen (animals) 2. building materials = structure cellulose (plants) chitin (arthropods & fungi)

16 POLYSACCHARIDES~ many sugars Ex: STARCH polymer of αlpha glucose linked by α 1-4 glycosidic linkages Function: Energy storage in PLANTS Most animals have the enzymes to hydrolyze starch, too

17 POLYSACCHARIDES~ many sugars TWO KINDS OF STARCH: amylose = unbranched starch amylopectin = branched starch

18 POLYSACCHARIDES~ many sugars EX: GLYCOGEN alpha 1-4 glycosidic bonds like starch More branched than amylopectin FUNCTION: Energy storage in ANIMALS Stored in liver and muscle tissue

19 POLYSACCHARIDES~ many sugars Example: CELLULOSE (PLANTS ) FUNCTION: Structural Major component in cell walls Most abundant organic compound on Earth beta (ß) 1-4 glycosidic linkages

20 Enzymes that digest starch by hydrolyzing alpha linkages can t hydrolyze beta linkages in cellulose Cellulose in human food passes through the digestive tract as insoluble fiber Some microbes use enzymes to digest cellulose Many herbivores, from cows to termites, have symbiotic relationships with these microbes

21 POLYSACCHARIDES EX: CHITIN FUNCTION: Structural Structural polysaccharide made from ß glucose with a NITROGEN containing group attached

22 Major component of: Exoskeletons in Arthropods Cell walls in Fungi Dissolvable surgical thread

23 Lipids: Fats & Oils

24 Lipids long term energy storage concentrated energy

25 Lipids Lipids are composed of C, H, O long hydrocarbon chains (H-C) Family groups fats phospholipids steroids Do not form polymers big molecules made of smaller subunits not a continuing chain

26 Fats Structure: glycerol (3C alcohol) + fatty acid fatty acid = long HC tail with carboxyl (COOH) group head enzyme H 2 O dehydration synthesis

27 Building Fats Triacylglycerol (trigyceride) 3 fatty acids linked to glycerol ester linkage = between OH & COOH hydroxyl carboxyl

28 Dehydration synthesis H 2 O dehydration synthesis enzyme H 2 O enzyme H 2 O enzyme H O

29 Fats store energy Long HC chain polar or non-polar? Why do humans like fatty foods? hydrophilic or hydrophobic? Function: energy storage concentrated all H-C! 2x carbohydrates cushion organs insulates body think whale blubber!

30 Saturated fats All C bonded to H No C=C double bonds long, straight chain most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits

31 Unsaturated fats C=C double bonds in the fatty acids plant & fish fats vegetable oils liquid at room temperature the kinks made by double bonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated?

32 Saturated vs. unsaturated saturated unsaturated

33 Phospholipids Structure: glycerol + 2 fatty acids + PO 4 PO 4 = negatively charged It s just like a penguin A head at one end & a tail at the other!

34 Phospholipids Hydrophobic or hydrophilic? fatty acid tails = hydrophobic PO 4 head = hydrophillic split personality attracted to water Come here, No, go away! Come here, No, go away! interaction with H 2 O is complex & very important! repelled by water

35 Phospholipids in water Hydrophilic heads attracted to H 2 O Hydrophobic tails hide from H 2 O can self-assemble into bubbles bubble = micelle can also form a phospholipid bilayer early evolutionary stage of cell? water bilayer water

36 Why is this important? Phospholipids create a barrier in water define outside vs. inside they make cell membranes! Tell them about soap!

37 Steroids Structure: 4 fused C rings +?? different steroids created by attaching different functional groups to rings different structure creates different function examples: cholesterol, sex hormones cholesterol

38 Cholesterol Important cell component animal cell membranes precursor of all other steroids including vertebrate sex hormones high levels in blood may contribute to cardiovascular disease

39 Cholesterol Important component of cell membrane helps keep cell membranes fluid & flexible

40 From Cholesterol Sex Hormones What a big difference a few atoms can make!

41 Let s build some Lipids!

42 Ghosts of Lectures Past (storage)

43 Phospholipids & cells Phospholipids of cell membrane double layer = bilayer hydrophilic heads on outside in contact with aqueous solution outside of cell and inside of cell hydrophobic tails on inside form core forms barrier between cell & external environment Tell them about soap!