Chapter 3 Biological Molecules
3.1 Synthesis of Molecules
Chemical Reactions Metabolism: all chemical reactions by which cells acquire and use energy Condensation or synthesis: builds a large molecule from smaller subunits; water is released Hydrolysis: uses water to break a molecule into smaller subunits Monomers: subunits of larger molecules Simple sugars, fatty acids, amino acids, and nucleotides Polymers: consist of multiple monomers
3.2 Carbohydrates
Simple Sugars Carbohydrate: organic compound that consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio Monosaccharides: simplest type of carbohydrates: Glucose, fructose, ribose Cells use monosaccharides for cellular fuel Monosaccharides are also used as: Precursors for other molecules Structural materials to build larger molecules
Synthesis between simple sugars Disaccharides: two monosaccharides Lactose: glucose + galactose Sucrose: glucose + fructose Polysaccharides: chains of hundreds or thousands of monosaccharide monomers Cellulose, Starch, Glycogen
3.3 Lipids
Non-polar organic molecules Lipids: fatty, oily, or waxy organic compounds Lipids contain fatty acids: consist of a long hydrocarbon “tail” with a carboxyl group “head” The tail is hydrophobic The head is hydrophilic Fats: lipid that consists of a glycerol molecule with one, two, or three fatty acids Saturated (solid) fats and Unsaturated (oily) fats
Other lipids Phospholipid: main component of cell membranes Contains phosphate group (hydrophilic) and two nonpolar fatty acid tails In a cell membrane, phospholipids are arranged in two layers called a lipid bilayer Steroids: lipids contain a rigid backbone of carbon atoms arranged in four rings Cholesterol, estrogen and testosterone
3.4 Proteins
Amino Acids Twenty kinds of monomers called amino acids An amino acids contain a side chain called an “R group” defines the kind of amino acid The covalent bond that links amino acids is called a peptide bond Proteins are polypeptides or hundreds to thousands of amino acids
Protein Structure determines Function Primary structure: linear series of amino acids Secondary structure: the twists and folds of a polypeptide chain Tertiary structure: regions of protein adjoin to create compact domains Quaternary structure: two or more polypeptide chains joined together
Denaturization Heat, shifts in pH, salts or detergents can denature (unfold) a protein by breaking hydrogen bonds Denaturation causes a protein to lose its function
3.5 Nucleic Acids
Nucleotides Nucleotide: a 5 carbon sugar bonded to a nitrogen- containing base and one, two, or three phosphate groups Example: ATP (adenosine triphosphate); an energy carrier in cells Polynucleotides in which the sugar of one nucleotide is bonded to the phosphate group of the next RNA (ribonucleic acid DNA (deoxyribonucleic acid