Final answer:
The claim that all functional DNA sequences in a cell code for protein products is false. Not all DNA sequences are genes that code for proteins; some have regulatory roles or code for ribosomal and transfer RNAs. Only a subset of genes are expressed in any one cell, depending on the cell's function and environment.
Step-by-step explanation:
The assertion that all functional DNA sequences inside a cell code for protein products is false. The genome of a cell contains both coding and non-coding regions. Functional DNA sequences that do code for proteins are known as genes, and these are the blueprints for protein synthesis. However, there are also DNA sequences that do not code for proteins but have other essential roles, such as regulatory functions, encoding tRNAs and rRNAs, and maintaining chromosomal structures and telomeres.
It is important to note that cells do not always produce proteins from every gene they possess. Gene expression can be selective and context-dependent. Moreover, not every cell in a multicellular organism expresses all available genes; they only express the genes required for their specific functions.
The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to protein. This dogma helps understand how gene expression underlies the phenotype of a cell, which can change in response to environmental conditions. Thus, while genes encode the information to make proteins, only a subset of these genes is expressed in any given cell at a certain time.