Question

Scientists are studying the protein in the Na+ -K+ pump found in nerve and muscle cells from a pig. They are interested in learning how DNA and proteins from two different cells from the same organism compare to one another. Describe the results scientists should see if they test both cells for the presence of the gene that produces this protein in the Na+ -K+ pump. Describe how protein synthesis is required to express the gene that produces this protein in the Na+ -K+ pump.

Answer 1

Muscle and nerve cells both contain the complete genome of the organism contained within their DNA. This means that both cells will contain all the same genes including the gene coding for the protein required in the sodium potassium pump. (Note the difference between cellular types and functions is the EXPRESSION of genes is different; all cells share the same genes but do not necessarily express them).

If both cells require the sodium/potassium pump and associated proteins than it is likely the exact same gene. Proteins are created through expression of genes. First the gene (a discrete section of DNA on a chromosome) is transcribed into an RNA message in the nucleus (RNA is similar to DNA and contains just the gene itself. Think of it as a post it note that has been copied from an encyclopedia of genes. Then the RNA is translated into a protein, which is a long chain of amino acids. The particular order and properties of the constituent amino acids that make up the protein cause it to coil up and form a 3 dimensional structure with properties that govern its particular function in the cell. In this case, the protein plays a key role in the sodium potassium pump. Protein synthesis is a fascinating topic and for more information, study up on the central dogma of genetics.