The Structure and Function of Macromolecules
Macromolecules - larger molecules made from smaller ones. 4 major classes of macromolecules: carbohydrates, lipids, proteins, and nucleic acids. 3 of these are polymers because they are made from individual building blocks called monomers.
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Monomers - joined together through condensation or dehydration reaction (form macromolecules) Requires energy; uses covalent bonds (links together monomers) Water produced.
Water produced as by-product
Hydrolysis breaks polymers into monomers. Water added to polymer; breaks bonds, creates monomers (i.e. digestive process in animals)
Carbohydrates 1Carbohydrates - sugars (monomers) and polymers. AMonosaccharides - simple sugars. BDisaccharides - double sugars (monosaccharides linked together) CPolysaccharides - polymers of monosaccharides. Sugars named with –ose.
Monosaccharides needed for cellular work. Help to synthesize other macromolecules.
Maltose - 2 glucose molecules. Sucrose - 1 glucose, 1 fructose.
Polysaccharides - energy storage. Starch - energy storage polysaccharide for plants. Cellulose – polysaccharide; plant cell walls. Animals store energy as glycogen.
Chitin - polysaccharide - makes up exoskeleton of arthropods (like crustaceans and our sowbugs!).
Chitin is used in surgery
Lipids - no polymers (exception) Lipids nonpolar (no affinity for water) Fat made from glycerol and fatty acids.
Saturated fatty acid - No carbon-carbon double bonds in carbohydrate chain. (hydrogen at every possible position) Form bad fats - solid at room temperature (butter, lard)
No double-double bonds
unsaturated fatty acid - 1+ carbon-carbon double bonds. Formed by removal of hydrogen atoms from carbon skeleton. Form good fats - liquid at room temperature (oils)
Purpose of fat - energy storage. Gram of fat stores 2X as much energy as gram of polysaccharide. Fat also cushions vital organs. Layer of fat can also function as insulation.
http://www. healthline http://www.healthline.com/blogs/diet_nutrition/uploaded_images/fat-cat-712938.jpg
MOST IMPORTANT LIPID IN BIOLOGY = Phospholipid Phospholipids have 2 fatty acids attached to glycerol. Fatty acid tails are hydrophobic, phosphate group and attachments form hydrophilic head.
When phospholipids added to water, self-assemble with hydrophobic tails pointing toward center, hydrophilic heads on outside. Phospholipids in cell form bilayer; major component of cell membrane.
Hydrophilic Hydrophobic
Other Lipids Steroids - lipids with carbon skeleton consisting of 4 fused carbon rings. Cholesterol - component in animal cell membranes and hormones.
Cholesterol
Proteins - support, storage, transport, defenses, and enzymes. Made in ribosomes in cell. Proteins - amino acids linked together to form polymer. 20 different amino acids that can be linked together to form thousands of different proteins.
http://images. foodnetwork http://images.foodnetwork.com/webfood/images/gethealthy/nutritionalallstars/LeanProteins_header.jpg
Amino acids link - polypeptides - combine to form proteins. Amino acids made of hydrogen atom, carboxyl group, amino group, variable R group (or side chain). R group makes amino acids different from one another.
Shape of protein determines function. Shapes - 3 dimensional - determined by sequence of amino acids.
Primary structure of protein - linear sequence of amino acids determined by genetics.
Secondary structure - two shapes are usually formed: alpha coils or beta sheets.
Tertiary structure determined by interactions among R groups.
Quarternary structure - joining of 2+ polypeptide subunits. Collagen and hemoglobin examples.
Protein’s shape can change due to environment. pH, temperature, or salinity (salt concentrations) change - protein can denature (starts to fall apart) Some proteins can return to functional shape after denaturation, others cannot.
Nucleic acids Amino acid sequence of polypeptide programmed by a gene. 2 types of nucleic acids: ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).
http://www. uic. edu/classes/bios/bios100/lecturesf04am/nucleotides http://www.uic.edu/classes/bios/bios100/lecturesf04am/nucleotides.jpg
DNA gives information so RNA can create proteins. Flow of genetic information - DNA -> RNA -> protein. Protein synthesis occurs in ribosomes.
Monomers of nucleic acids - nucleotides. Nucleotides made up of 3 parts: nitrogen base, five-carbon sugar, and phosphate group. Nitrogen bases, rings of carbon and nitrogen, come in 2 types: purines and pyrimidines.
Pyrimidines - cytosine (C), thymine (T), and uracil (U in RNA only). Purines - adenine (A) and guanine (G). Pyrimidines - single six-membered ring; purines - five-membered ring.
http://library.med.utah.edu/NetBiochem/pupyr/pupy3.gif
In RNA - sugar is ribose; DNA - sugar is deoxyribose. Difference between sugars is lack of oxygen atom in deoxyribose.
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RNA single-stranded - linear shape. DNA forms double helix. Sugar and phosphate forms backbone of double helix while nitrogen bases form connection between backbones.
Adenine (A) always pairs with thymine (T) guanine (G) with cytosine (C). Due to six and five membered rings – shapes are compatible. Two strands are complementary.
http://www.emunix.emich.edu/~rwinning/genetics/pics/dna2.gif
DNA used to show evolutionary similarities between species. Two species that appear to be closely-related based on fossil and molecular evidence also more similar in DNA and protein sequences than more distantly related species.