Mark argues that proteins within the body have two functions structure and transport sarah disagrees which significant function of proteins did mark omit from his list

Proteins are large complex compounds made up of one or more polypeptide chains.  

They play many major roles in living organisms:

Structural role: They are called building block of the body. They provide strength and structure to the cell. For example, keratin protein is found in nails, hair, and skin, collagen can be found in connective tissue et cetera.

Transport: They help in transport of material across the cell membrane. They form carriers and channels across the lipid bilayer which assist the transport of materials across it.

Immunological role: Antibodies or immunoglobulins are primarily protein in nature which helps our body to fight against a pathogen.

Biochemical reactions: In living organisms, biochemical reactions are majorly aided by enzymes which are mainly protein in nature (except ribozyme).

Chemical messenger: Proteins also occur as chemical messengers in the form of hormones such as insulin et cetera.

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.