a. Explain, in terms of their electrons, how an atom of carbon and two atoms of oxygen form a molecule of b. Explain the functions of hydrogen bonds. c. Explain the function of disulfide bonds.

Carbon has 4 valence electrons, and oxygen has 6 valence electrons. To achieve a stable electron configuration, carbon needs to share 4 electrons, while each oxygen atom needs to share 2 electrons. In a molecule of carbon dioxide (CO2), carbon shares two of its electrons with each oxygen atom, forming a double covalent bond with each oxygen atom. This arrangement leads to the formation of a linear molecule with carbon in the center and oxygen atoms on each side, and all the atoms have a stable electron configuration.

Hydrogen bonds are a type of intermolecular force that occurs between a hydrogen atom that is covalently bonded to an electronegative atom (like oxygen or nitrogen) and another electronegative atom. They are weaker than covalent bonds but are still essential for several functions in biological and chemical systems, such as: 1. Stabilizing the structure of proteins: Hydrogen bonds play a crucial role in maintaining the secondary structure of proteins, like the alpha-helix and beta-sheet formations. 2. Stabilizing the structure of nucleic acids: Hydrogen bonds are responsible for holding the two strands of DNA together through base pairing (adenine and thymine, guanine, and cytosine). 3. Water properties: Hydrogen bonding between water molecules leads to its high boiling point, high specific heat capacity, and high heat of vaporization, which are essential for life processes. 4. Solvent properties: Hydrogen bonds are also responsible for water's exceptional ability to dissolve a variety of substances, as water molecules can form hydrogen bonds with solute particles, facilitating their dissolution.

Disulfide bonds are covalent bonds formed between two sulfur atoms, which are each attached to a cysteine amino acid residue in a polypeptide chain. They play an essential role in stabilizing the tertiary and quaternary structure of proteins by connecting different parts of the same polypeptide chain or between separate polypeptide chains in multi-subunit proteins. Disulfide bonds provide strength and rigidity to protein structures and can influence protein folding, stability, and function. In some cases, they can also play a direct role in a protein's catalytic activity, as seen in certain enzymes.