Chemistry: Carbon and Functional Groups

Carbon and Its Bonding

• Carbon can form four covalent bonds, allowing complex molecular structures.
• Primarily bonds with O, N, S, P, and H, creating diverse compounds.
• Hydrocarbons consist solely of carbon and hydrogen, exhibiting nonpolar characteristics.

Functional Groups

• Functional groups attach to hydrocarbon cores, influencing chemical properties and reactions.
• Key functional groups include:
  • Hydroxyl Group (-OH)
  • Carbonyl Group (C=O)
  • Carboxyl Group (-COOH)
  • Amino Group (-NH₂)
  • Ester Group (-COO-)
  • Phosphate Group (-PO₄³⁻)

Isomers

• Isomers are molecules with the same formula but different structures.
• Structural isomers have distinct carbon skeletons.
• Stereoisomers differ in the spatial arrangement of groups attached.
• Enantiomers are chiral molecules that are mirror images of each other, such as D-sugars and L-amino acids.

Macromolecules

• Polymers are large molecules formed from repeating monomers.
• Monomers are the individual subunits, with major classes including carbohydrates, nucleic acids, proteins, and lipids.

Polymer Synthesis and Breakdown

• Dehydration synthesis creates polymers by removing water, joining monomers.
• Hydrolysis breaks down polymers into monomers by adding water.

Carbohydrates

• Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio (CH₂O).
• Serve as energy storage molecules; examples include sugars, starches, and glucose.

Monosaccharides

• Simplest form of carbohydrates, vital for energy.
• Significant monosaccharides include glucose (C6H12O6), fructose (isomer of glucose), and galactose (stereoisomer of glucose).

Disaccharides

• Formed from two monosaccharides via dehydration synthesis.
• Common disaccharides:
  • Sucrose
  • Lactose
  • Maltose

Polysaccharides

• Long chains of monosaccharides linked through dehydration.
• Function in energy storage: starch in plants and glycogen in animals.
• Provide structural support: cellulose in plants and chitin in fungi.

Nucleic Acids

• Nucleic acids are polymers made of nucleotides.
• Nucleotides consist of sugar, phosphate, and a nitrogenous base.
• Types of nitrogenous bases:
  • Purines: Adenine and Guanine
  • Pyrimidines: Thymine, Cytosine, Uracil

DNA Structure

• Encodes genetic information for amino acid sequences.
• Consists of two polynucleotide strands forming a double helix stabilized by hydrogen bonds.
• Base pairing rules: A pairs with T (or U in RNA), C pairs with G.

RNA Structure

• Similar to DNA but contains ribose sugar and uracil instead of thymine.
• Serves to convey genetic information for protein synthesis.

Disaccharides and Energy Molecules

• Adenosine triphosphate (ATP) acts as the energy currency of the cell.
• Nicotinamide adenine dinucleotide (NAD⁺) and flavin adenine dinucleotide (FAD⁺) carry electrons.

Proteins

• Perform diverse functions: catalysis, defense, transport, movement, support, regulation, and storage.
• Polymers made from amino acid monomers, each with central carbon, amino group, carboxyl group, hydrogen, and variable R group.

Peptide Bonds

• Formed through dehydration synthesis between the amino group and carboxyl end of amino acids.

Protein Structure Levels

• Primary structure: sequence of amino acids.
• Secondary structure: interactions in the peptide backbone, forming helices or sheets.
• Tertiary structure: final folded shape stabilized by various interactions.
• Quaternary structure: arrangement of multiple polypeptide chains.

Additional Structural Features

• Motifs: recurring secondary structural elements aiding in function prediction.
• Domains: functional units within proteins, often serving different roles.

Chaperones

• Assist proteins in proper folding; deficiencies can lead to diseases like cystic fibrosis.

Denaturation

• Loss of protein structure and function due to changes in pH, temperature, or ionic concentration.

Lipids

• Comprise a diverse group of molecules, typically insoluble in water, due to high nonpolar C-H bonds.
• Include fats, oils, waxes, and some vitamins.

Fats

• Triglycerides are composed of one glycerol and three fatty acids.
• Fatty acids can be saturated (no double bonds) or unsaturated (one or more double bonds).
• Trans fats are artificially created by hydrogenation.

Phospholipids

• Comprised of glycerol, two fatty acids (nonpolar tails), and a phosphate group (polar head).
• Essential for forming biological membranes.

Micelles and Phospholipid Bilayer

• Micelles: lipid molecules orient with heads towards water and tails away.
• Phospholipid bilayer: forms when two layers align with heads outward and tails inward, creating a barrier.