What is the difference between interspecific and intraspecific competition?

Interspecific competition = different organisms compete for a resource in the same ecosystem

intraspecific competition = same organisms compete for a resource in the same ecosystem

Proteins are large biological molecules consisting of one or more chains of amino acids.  Proteins differ from one another primarily in their sequence of amino acids, which is decided by the nucleotide sequence of their make-up, and which usually results in folding of the protein into a three-dimensional structure that determines its job. 
    Nucleic acids are linear polymers (chains) of nucleotides. Each nucleotide consists of three things: a purine , nitrogenous base a pentose sugar, and a phosphate group.  
    
 Basically Proteins are chains of amino acids, nucleic acids are chains of nucleosides (base+sugar+phosphate), and the sequence of nucleic acid results in the specific sequence of amino acids in the protein, finnally determining its shape and function.