Chapter 5: Macromolecules

Macromolecules A large molecule in a living organism –Proteins, Carbohydrates, Nucleic Acids Polymer- long molecules built by linking repeating building blocks in a chain Monomer- units that serve as building blocks of polymer

Dehydration Synthesis -How cells link together monomers -Monomers have H atoms and hydroxyl groups -Add a monomer to a chain, a water molecule is released

Hydrolysis -Opposite of dehydration synthesis -Bond in a polymer are broken by addition of water

1. Carbohydrates Carbohydrates: include sugars and polymers of sugar Monosaccharides: the simplest carbohydrate, made of a single sugar

Monosaccharides The simplest carbohydrate made of a single sugar Have molecular formulas multiple of CH 2 0 (Most common sugar is glucose C 6 H ) Have a hydroxyl group (OH) and a carbonyl group (C=0) OH group make it an alcohol and the C=0 make it an aldehyde or ketone

Fig. 5-3 Dihydroxyacetone Ribulose Ketoses Aldoses Fructose Glyceraldehyde Ribose Glucose Galactose Hexoses (C 6 H 12 O 6 ) Pentoses (C 5 H 10 O 5 ) Trioses (C 3 H 6 O 3 )

Though often drawn as linear skeletons, in aqueous solutions many sugars form rings Monosaccharides serve as a major fuel for cells (glucose) Most sugars end in -ose Monosaccharides (cont’d)

Disaccharide A double sugar created when dehydration synthesis joins Ex: 2 glucose -> maltose (malt sugar makes beer) Glycosidic linkage: covalent bond between 2 sugars of a disaccharide

(b) Dehydration reaction in the synthesis of sucrose GlucoseFructose Sucrose MaltoseGlucose (a) Dehydration reaction in the synthesis of maltose 1–4 glycosidic linkage 1–2 glycosidic linkage

Many act as storage molecules of sugar, that cells break down for energy Hundreds or thousands of monosaccharides joined together (glycosidic links) Polysaccharide

Polysaccharide- Starch Made of all glucose and found in plants Plants store starch and break into glucose when needed for energy Humans and animals hydrolyze starch when they eat it (found in wheat, corn, rice, potatoes)

Fig. 5-6 (b) Glycogen: an animal polysaccharide Starch Glycogen Amylose Chloroplast (a) Starch: a plant polysaccharide Amylopectin Mitochondria Glycogen granules 0.5 µm 1 µm

Glycogen is hydrolyzed to release glucose when needed Excess sugar in animals is stored as glycogen in liver and muscles Polysaccharide- Glycogen

Glycogen is hydrolyzed to release glucose when needed A component of a plant’s cell wall, gives them structure Polysaccharide- Cellulose A polymer of glucose, but the glycosidic linkages differ. Cellulose molecules connected by hydrogen bonds and form fiber

Fig. 5-9

1-4 linkage of alpha glucose molecules 1-4 linkage of beta glucose molecules

Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods Chitin also provides structural support for the cell walls of many fungi Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig The structure of the chitin monomer. (a) (b) (c) Chitin forms the exoskeleton of arthropods. Chitin is used to make a strong and flexible surgical thread.

What does this say about their solubility? Compounds that consist mainly of C and H atoms linked by nonpolar covalent bonds Lipid Ex: fats, oils, waxes

- a 3 carbon alcohol with hydroxyl group A large lipid made of glycerol and fatty acids Fats Ex: fats, oils, waxes 1 fat molecule = 1 glycerol and 3 fatty acids Function is energy storage (1 g of fat stores more than 2x as much energy as 1 g of starch)

Fig Fatty acid (palmitic acid) Glycerol (a) Dehydration reaction in the synthesis of a fat Ester linkage (b) Fat molecule (triacylglycerol)

No double bond in fatty acid Solids (lard, butter- animal fats) Leads to heart disease, plaque in blood vessels Saturated Fats

the fatty acid contains double bonds, preventing the skeleton from having the max # of hydrogen’s. Molecules can’t pack together tightly and form liquids at room temp (oils and plant fats) Unsaturated Fats

A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds These trans fats may contribute more than saturated fats to cardiovascular disease Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Major component of cell membranes Similar to fat, but contain phosphorus and have a fatty acid (not 3) Phospholipids

1 fatty acid and an alcohol More hydrophobic than fats Natural coating on fruit Insects have to keep from drying out Waxes

lipids whose carbon skeleton is bent to form 4 fused rings all steroids have 3-6 sided rings and 1-5 sided ring Ex: cholesterol found in animal cell membranes and animal cells use it to make other steroids (estrogen and testosterone) Steroids

Fig. 5-15