Unit #2: Biochemistry STRUCTURE & FUNCTION OF FOUR MACROMOLECULES What are the four main biomolecules? How is each biomolecule structured? What are their roles in life? Where do we find them in our body? 1. Carbohydrates ² Functions: Main source of energy Structural support in plants and some animals ² Composed of: C, H, and O atoms usually in a 1:2:1 ratio ² Simple sugars = monosaccharides glucose, fructose, galactose ² Double sugars = disaccharides sucrose, lactose, maltose ² Complex sugars = polysaccharides starch, glycogen, cellulose
Shape Matters! Glucose Fructose Galactose Ø Determine the chemical formula for each of the above monosaccharides: All have the same chemical formula: C 6 H 12 O 6 Ø All of these simple sugars have the same number and type of atoms, yet the arrangement of atoms in each molecule is different, which produces a different overall shape. Ø The different shape gives each of these sugars a different taste! 2. Lipids ² Large & Varied Group! ² Fats, Oils, & Waxes ² Do not dissolve in water! ² Composed of: mostly C and H atoms ² Does not have a repeating monomer, but all lipids have at least one fatty acid chain. ² Functions: Insulation Energy storage Waterproofing Structure Hormones
What is different between a saturated fat and an unsaturated fat? Fatty acids that contain one or more double bonds between two carbon atoms are said to be UNSATURATED. Saturated fats are linear in shape. They easily stack upon one another to clog up blood vessels. Naturally occurring unsaturated fats are bent in shape. Monounsaturated = 1 double bond Polyunsaturated = 2 or more double bonds Fatty acids with only single covalent bonds between carbon atoms are said to be SATURATED. What is a trans fat? Most trans fats are created inducstrially through partial hydrogenation of plant oils. Trans fats occur when H atoms are on opposite sides of the double bond, thus creating symmetry. As a result the fatty acid is linear, so it behaves like a saturated fat in your body. Have a higher melting point, which is good for baking and gives them a longer shelf-life. Cis fats occur when H atoms are on the same side of the double bond, thus creating asymmetry. As a result, the fatty acid is bent in shape.
Where do you find fats in your diet? Triglyceride Body fat functions to: ü Cushion organs ü Insulation ü Long-term energy storage Composed of: ü Glycerol + 3 fatty acids
Phospholipid Phospholipids are the building blocks of a cellular membrane. Phospholipids have a: ü Polar head that is hydrophilic ( water-loving ). ü Nonpolar tails that are hydrophobic ( water-fearing ). Steroids Carbon skeleton has: ü Four interconnected rings ü Different functional groups attached Group of lipids derived from cholesterol Includes a variety of hormones: ü sex hormones ü glucocorticoids, which regulate glucose metabolism ü mineralocorticoids, which regulate water and electrolyte levels in blood
3. Proteins ² Composed of: C, H, O, and N (S in a few) ² Functions: Structure Storage Transport Defense Signaling A protein s structure is created on various levels: Primary structure Amino Acids Secondary structure β-pleated sheets α-helix Tertiary structure Quaternary structure
Primary Structure: Sequence of Amino Acids Amino group Carboxyl group Side chain The 20 Different Amino Acids
Amino acids are held together by covalent peptide bonds. 4. Nucleic Acids ² Functions: Store and transmit genetic material ² Composed of: C, H, O, N, and P atoms ² Only two types of polymers: DNA deoxyribonucleic acid RNA ribonucleic acid ² Monomer: nucleotide ² Nucleotides are made of three things: nitrogenous base 5-carbon sugar phosphate group
What is different about the sugars in a nucleotide found in RNA versus in DNA? A nucleotide found in RNA has the sugar ribose. A nucleotide found in DNA has the sugar deoxyribose. Deoxyribose has one less oxygen atom than ribose. DNA vs. RNA What is different between these two molecules besides their sugars? RNA has uracil (U) instead of thymine (T). RNA is a single helix instead of a double helix.