This week in biology we started off by taking a quiz on inheritance. This took most of class so we spent the remainder discoing 4.11 and 4.12. That night we watched a 15 minute video on the evolution of stickleback fish and how after generations of living in freshwater, something in their genetics stopped coding for a pelvic spine. From observing these fish scientists learned that our DNA can still possess a gene but choose not to express it through a process called gene regulation. These regulatory switches known as "enhancers" in eukaryotes are specific areas in the DNA where specific activator proteins will bind to turn the gene on or off. What is interesting is the same gene can be expressed in one location on the organism while not expressed in another. While it is the same gene throughout the body, there are multiple switches that can enable or disable it in the selected region.
We studied the first section of the regulation unit this week as well and learned about developmental genetics. The key information here was how every cell in our body can contain the same DNA yet have vastly different functions, Enter the process of differentiation where at the cells early stages it recieves signals from surrounding cells that determine its developmental pathway. We also learned about transposable elements which are non-coding DNA segments that catalyze their own replication and movement throughout the genome. Wednesday the Juniors were out taking the SAT and we spent the next two days working on a specific presentation of a regulation system (circulatory, exretory. nutritional, ect.). This is to famiiorize ourselves with the systems we will study this unit of regulation