My lecture notes

• What is the central element in biomolecules?

  Carbon
• How many covalent bonds can carbon form with other atoms?

  Four
• What are the two main types of compounds formed by carbon atoms in biomolecules?

  Aliphatic and cyclic compounds
• What type of compound is cholesterol?

  Cyclic
• What are functional groups in biomolecules?

  Groups of atoms that give specific properties
• Name a functional group that adds acidity to a molecule.

  Carboxyl (-COOH)
• Which functional group can carry a negative charge after losing a proton?

  Phosphate, sulfate, carboxylate
• What charge do basic groups carry when they gain a proton?

  Positive
• What functional group is found in alcohols?

  Hydroxyl (-OH)
• What type of charge does an acidic group carry after losing a proton?

  Negative (anion)
• Which functional group is characterized by nitrogen and has basic properties?

  Amino (-NH2)
• Name a functional group found in aromatic compounds.

  Phenyl
• What property does the amino group impart to biomolecules?

  Basicity
• Where are small organic molecules found in cells?

  In the cytosol (aqueous phase)
• How many different types of small organic molecules are in a typical cell?

  100-200
• What property makes small organic molecules soluble in water?

  They are polar or charged
• What are macromolecules?

  Large polymers made of repeating monomer units
• What role do macromolecules play in cells?

  They are major components of cells
• How many units can macromolecules contain?

  From tens to millions
• Name the monomers that make up proteins.

  Amino acids
• What monomers make up polysaccharides?

  Simple sugars (monosaccharides)
• What are the monomeric units of nucleic acids?

  Nucleotides
• What role do noncovalent interactions play in biological systems?

  Essential for molecular interactions
• Name a molecular interaction facilitated by noncovalent interactions.

  Enzyme-substrate binding
• What type of noncovalent interaction occurs between polar, ionized groups?

  Hydrogen bonds and electrostatic interactions
• What interaction occurs between nonpolar groups in aqueous systems?

  Hydrophobic interactions
• What types of bonds can form hydrogen bonds?

  O−H and N−H bonds
• What charge does hydrogen have in a hydrogen bond?

  Partial positive charge
• What type of atom does hydrogen interact with in a hydrogen bond?

  Electronegative atom (O or N)
• How are the atoms arranged in a hydrogen bond?

  Collinearly among donor, hydrogen, and acceptor
• Can polar molecules form hydrogen bonds with water?

  Yes, they are hydrophilic
• Why can’t nonpolar molecules form hydrogen bonds with water?

  They lack polar bonds and are hydrophobic
• What term describes molecules that do not dissolve in water?

  Hydrophobic
• What type of molecule contains both polar and nonpolar groups?

  Amphipathic
• What are electrostatic interactions?

  Interactions between charged groups with net electric charges
• What is the term for attraction between opposite charges in electrostatic interactions?

  Salt bridges
• What happens between like charges in electrostatic interactions?

  Repulsion
• What type of molecules form hydrophobic interactions?

  Nonpolar (hydrophobic) residues
• Why do nonpolar residues associate with each other in water?


  To minimize contact with water
• What is the effect of hydrophobic interactions on the nonpolar-water contact area?

  It reduces the exposed hydrophobic area