Original Passage:
Derived partially from the Greek prefix epi-, which means "on" or "in addition," the epigenome is to the cell what an organism's sensory organs are to the individual. Like an octopus's tentacles that, among other functions, gather information from the environment so that the brain can tell the neurons, "Move your eighth arm here, " the epigenome gathers information from the cell's environment and tells the genes, "turn on" or "turn off." In science lingo, it governs "gene expression." Based on emerging evidence, the epigenome appears to play a vital role in most, if not all, cellular activity, from metabolism to fertilization.
Source: Pray, L. A. (2005). Soiled Genes: Can toxic exposures be inherited? Orion Magazine. Retrieved December 15, 2005, from http://www.oriononline.org/pages/om/05-6om/Pray.html.
The original passage contains three relevant pieces of information that need restating in order to create an accurate paraphrase. The highlights in paragraph A below identify these pieces of information.
(A) Derived partially from "the Greek prefix epi-, which means "on" or in addition," the epigenome is to the cell what an organism's sensory organs are the individual. Like an octopus's tentacles that, among other functions, gather information from the environment so that the brain can tell the neurons, "Move your eighth arm here, " the epigenome gathers information from the cell's environment and tells the genes, "turn on" or "turn off." In science lingo, it governs "gene expression." Based on emerging evidence, the epigenome appears to play a vital role in most, if not all, cellular activity, from metabolism to fertilization.
Paragraph B below restates the highlighted information and cites the source. Notice that it is roughly the same length as the original. This is as it should be; a summary would need to be shorter. Consider Paragraph B a first draft. It's still a little wordy.
(B) Pray (2005) compares the epigenomes of a cell to the sensory organs of an individual. She likens them to octopus tentacles gathering information from the environment so that the brain has something to work with when deciding what instructions to send the neurons governing specific tasks, like moving an arm for instance. The epigenomes turn genes governing cellular activity on or off. The latest research suggests that epigenomes (the Greek prefix epi-, meaning "on"), are an integral and decisive part of practically every cellular activity, from metabolism to fertilization, known to science.
Paragraph C is a final revision based on the draft above. Notice how the sentence structure and word choices have evolved and yet the essential meaning of the paragraph has not changed.
(C) Reporting on recent research, Pray (2005) observes that epigenomes (the prefix epi-, meaning "on" in Greek) are much like the tentacles of an octopus. Attached to individual cells, the epigenomes collect and provide external data to specific genes as do the tentacles to the brain of an octopus. As the octopus's brain transmits a signal via a neuron back to one of its tentacles telling it to move, the latest scientific evidence indicates that epigenomes are the transmitters responsible for conveying the information that flips the on/off switch on the genes governing practically every kind of cellular-activity, from metabolism to fertilization, known to science.