According to Michael Meaney of McGill University, "Everything we have learned about molecular biology has show that gene activity is regulated by the intracellular environment" (195). Both the outer environment and the DNA sequence affect gene expression indirectly, but some of the factors that determine more directly what genes will be expressed are "hormones released by endocrine organs, cytokines from the immune system, neurotransmitters form neurons, nutrients derived from food" (195). For each of these four factors, choose a specific example of a biological pathway. Explain what environmental influences would initiate or affect the example, how each example moves through the body to reach target cells, and how the example affects the intracellular environment to change gene expression.
Adele Padgett adele.padgett@gmail.com
One example of a hormone released by an endocrine organ would be epinephrine.
ReplyDeleteThe epinephrine is released from the adrenal glands during a stressful situation. This could be when a person is panicked because he or she is being chased by a bear. The epinephrine is signaled by a process called signal transduction (Campbell 979). The epinephrine released by the adrenal glands and travels via the blood stream to interact with the cells necessary. Then a cascade of molecules interact with each other to produce the signal for the leg muscles to work hard to run from the bear (http://www.wiley.com/college/boyer/0470003790/animations/signal_transduction/signal_transduction.htm). This cascade of events begins with the epinephrine using the trans-membrane protein, G protein-coupled receptor, to signal the inside of the cell to turn the GDP on to become GTP. This GTP then binds to the adenylyl cyclase to turn t on to send the message to the cAMP, which then activates the protein kinase A, and finally activates the enzyme that will break down glycogen (Campbell 979). This would finally be able to change the gene expression so that there is more glucose is provided in the bloodstream to power one’s legs to run away from the bear. This could be one of the environmental stress triggers that help to develop athletic skill. This hormone is only produced when the body is under extreme stress because the demanding environment. When the environment demands this type of reaction of the body, it may force a person to develop the skills necessary for success (Shenk 44).
Cytokines in the immune system are proteins that “help recruit and activate lymphocytes” to help fight off the pathogens that are infecting the system (Campbell 936). An environment influence that would demand this type of response could be as simple as an injury. When an knew is scraped while tripping over a tree root, it will start to swell, turn pink, and become very warm. This is because of the inflammatory response that is occurring. The inflammatory response begins with the mast cells releasing histamine to trigger nearby capillaries to widen creating the redness and the warmness of the injury (http://cellular-immunity.blogspot.com/2007/12/inflammatory-response.html). The histamines then also attract phagocytic cells that will then signal cytokines, which are already at the target cells because they traveled with the phagocytic cells via the blood stream, to activate and attract lymphocytes to kill off the pathogens at the injury site (Campbell 935). This fighting off of the pathogens with the signal from the cytokines would heal the wound and eventually close it up. The cytokines would be able to change the gene expression of the phagocytic cells by lock and key fit. This would turn the cells on to do their job and fight pathogens.
The neurotransmitters in the brain are the small packs of chemicals in the brain that help to carry information between different neurons. When the environment forces a human to learn, they are used to carry information via synapses to other neurons making connections throughout the brain and storing memories (http://its.sdsu.edu/multimedia/mathison/neurotransmitter/index.htm). The neurotransmitters are able to move via electrical shock. They are shot through synapses to arrive at different neurons during the process of thinking. Dentrites at the other end of the accepting neuron then catch the neurotransmitters by lock and key fit. The lock and key fit would also only admit certain neurotransmitters. The neurons, brain cells, would be the target cells in this case. If a person is in a stressful situation and all the oxygenated blood is fueling the muscles rather than any other organs, the neurons may be temporarily slowed and gene expression will change because their wouldn’t be enough fuel to keep the neurotransmitters from flying from neuron to neuron.
ReplyDeleteWhen one gets hungry during class, one may pull out a carb-filled snack such as Goldfish. After the Goldfish enters the mouth and goes through the stomach it enters the small intestine. In the small intestine there are many villi that consume the nutrients into the bloodstream that then travels to the liver to be filtered. Then, the nutrients in the bloodstream travel to targeted muscle tissue to help provide nutrients to function and grow (Campbell). The nutrients on the outside of the cell may affect the inside of the cell to trigger different hormones. For example, if there is too much glucose circulating the body and the cells, then the cells will trigger insulin to increase the taking up of glucose and store it. If there is too litter, then glucagen will be triggered to have the cells release the stored glucose into the bloodstream. Through the nutrients, they are able to signal internal responses from the cell that would change gene expression, in this case in the liver, to stimulate the secretion of the hormones to adjust the inter environment of the organism.
These four things would be able to relate to Shenk’s theory that people can get smarter when the environment demands it (44). The word smarter can be replaced by increased talent or achieve success. When the environment demands these chain of reactions to occur due to the strenuous mental drive to work hard at something, it will definitely make one be intelligent, successful, athletic, etc. Thus by the change in internal environment of the cell triggered by environment stimuli can alter gene expression under tough mental conditions to help one achieve their goals.