You discover a strain of E. coli that is unable to grow using lactose as its carbon source. When you sequence its genome, you discover a 30 nucleotide deletion in the lac operon promoter. All other regulatory elements and genes are present and display the wild-type sequence. You want to introduce a plasmid that will restore normal lac operon function, i. e such that lactose induces expression of all 3 lactose metabolism enzymes. In addition to a promoter, what is the minimum set of genetic elements you would have to include on this plasmid to accomplish your goal?

Bisphenol a (often called bpa) is a chemical found in products that people use every day, from water bottles to food containers to children's toys. unfortunately, bpa leaches out of its many products and makes its way into our bodies. what are the health effects of bpa exposure? ongoing research is finding that elevated exposure to bpa can affect a wide variety of developmental and physiological processes, but one of the first studies of bpa's health effects came about because of a simple mistake in the lab. at a laboratory at case western reserve university in 1998, geneticist patricia hunt was making a routine check of her female lab mice. as she extracted and examined developing eggs from the ovaries, she began to wonder what had gone wrong. she noticed that many of the eggs showed problems with their chromosomes, and some had irregular amounts of genetic material, which can lead to miscarriages and birth defects in mammals. she learned that a lab assistant had mistakenly washed the plastic mouse cages and water bottles with a harsh soap, releasing bpa from the plastic. knowing that bpa is an endocrine disruptor, a chemical that can enter organisms and mimic hormones, hunt set out to discover whether it had adversely affected her mice.