Ch4-5

• Living organisms are made mostly of carbon-based chemicals, which enter the biosphere through plants and photosynthetic organisms
• Carbon is unparalleled in its ability to form large, complex, and varied molecules, allowing for the diversity of organisms on Earth
• Proteins, DNA, carbohydrates, and other molecules in living matter are composed of carbon atoms bonded to each other and to atoms of other elements
• Organic chemistry is the study of carbon compounds
• Compounds containing carbon are considered organic, while those lacking carbon are considered inorganic
• Stanley Miller's experiment demonstrated that complex organic molecules could arise spontaneously under early Earth conditions, supporting the idea of abiotic synthesis of organic compounds
• Carbon atoms can form diverse molecules by bonding to four other atoms
• Valence electrons determine the kinds and numbers of bonds an atom will form with other atoms
• Carbon has four valence electrons and tends to form four bonds to satisfy the octet rule
• Nitrogen tends to form three bonds, oxygen tends to form two bonds, and hydrogen tends to form one bond to satisfy their respective octet rules
• Molecules are often represented in two-dimensional structural formulas, but their actual shape in three dimensions is crucial to their function
• Carbon chains can form the skeletons of most organic molecules, varying in length, straightness, branching, and presence of double or triple bonds
• Hydrocarbons, consisting of only carbon and hydrogen atoms, are major components of petroleum and are found in molecules like fats
• Isomers are compounds with the same number of atoms of the same elements but different structures and functions
• Structural isomers differ in the covalent arrangement of their atoms, while CIS-trans isomers differ in spatial arrangement due to double bonds
• Enantiomers are mirror images of each other and differ in shape due to the presence of an asymmetric carbon, important in the pharmaceutical industry for drug effectiveness
• Organic chemistry:

  • Is the study of carbon compounds
  • Carbon compounds can have similar molecular formulas but different structures and formations
  • Isomers are molecules with the same molecular formula but different 3D spatial arrangements
• Stereoisomerism:

  • Molecules can have the same molecular formula and sequence of bonded atoms but differ in their 3D orientation of atoms in space
  • Structural isomers have different connectivity
  • Stereoisomers have the same connectivity but differ in 3D orientation
• Functional groups:

  • Hydrocarbons are the underlying framework for more complex organic molecules
  • Chemical groups attached to carbon skeletons are called functional groups
  • Functional groups determine the properties and chemistry of molecules
  • Examples of functional groups: hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl
• Practice problems:

  • Organic chemistry is the study of carbon compounds
  • Sulfhydryl group is not present in the molecule
  • Amino group is most likely responsible for an organic molecule behaving as a base
  • Hydrocarbon with a double bond in its carbon skeleton is C
  • Sugar molecules are structural isomers as they have the same molecular formula but different connectivity
• Macromolecules are polymers built from monomers
• Monomers are small molecules that can be joined together to form more complex molecules called polymers
• Monomers are connected by a dehydration process, where two molecules are covalently bonded to each other with the loss of a water molecule
• Polymers can be disassembled to monomers by hydrolysis, which is the addition of water to break the bond between monomers
• Monosaccharides are the basic building blocks of carbohydrates
• Disaccharides consist of two monosaccharides joined by a covalent bond
• Polysaccharides are composed of many sugar building blocks and serve as storage material or building material for structures
• Carbohydrates serve as fuel and building material
• Carbohydrates include sugars and polymers of sugars
• Monosaccharides have molecular formulas that are some multiple of the unit CH2O
• Glucose, a common monosaccharide, has the molecular formula C6H12O6
• Monosaccharides can be classified as aldose or ketose sugars based on the location of the carbonyl group
• Disaccharides are formed by a glycosidic linkage, a covalent bond between two monosaccharides formed by a dehydration reaction
• Polysaccharides are macromolecules with hundreds to thousands of monosaccharides joined by glycosidic linkages
• Lipids are a diverse group of hydrophobic molecules that do not mix well with water
• Lipids include waxes, fats, phospholipids, and steroids
• Fats are large molecules made from glycerol and fatty acids through dehydration reactions
• Fats consist of a glycerol molecule and three fatty acids linked by ester linkages
• Fatty acids can be saturated (no double bonds) or unsaturated (one or more double bonds)
• Phospholipids have a glycerol molecule, two fatty acids, and a phosphate group