Evidence Prompt
Greulich in footnote 26-27 stresses the
importance of individual genes and their environments interacting to create a
complex developmental process. The expression of genes produces an effect by
interacting with other genes and environments. The study of the heights of
Japanese children in America versus Japan suggest that physical growth and
development is based on extra-cellular signals and by environmental influences.
All organisms must regulate which genes are expressed at a given time and
regulation of gene expression is essential for cell specialization in
multicellular organisms, which are made up of different types of cells each
with a distinct role. Use the Campbell book sections 18.2 and 18.3 to explain
how the environment interacts with gene regulation to produce specific effects
such as Japanese-American children growing taller than native Japanese
children, how height was greatest in the Middle Ages because of warmer climate,
and how twins can have differences based on their interaction between genes and
environment. Knowledge of protein and DNA characteristics should also be
referenced to the regulation of genes. Relate to the biology themes of
interdependence in nature, regulation, and relationship between structure and
function.
Kirk Chiu (krkpchiu@gmail.com)
The environment plays a significant role in the regulation of our genes as has been proven through countless experiments and through our study of how genes are switched on and off and at what intensity they are expressed. The test of heights between kids of Japanese descent in both the U.S. and Japan showing how Japanese-Americans are taller is one example of this. David Shenk discusses how these results are attributed to better nutrition given to children in the U.S. compared to those in Japan. This idea is supported by our knowledge on the regulation of genes, as in order to translate and transcribe genes, not only is energy needed, but also the products and messengers that take part in making this process work, many of which are derived from what we consume. For the kids in this study, those who got more nutrition (the kids raised in the U.S.) had the resources necessary to become taller and therefore their genes allowed them to grow, while comparatively when then kids were at a lack of nutrition their height directly suffered. These studies support the idea that humans are all supposed to be fairly tall, but are often suppressed by their environment. The kids that do not receive enough of the vital nutrients, like proteins and carbohydrates, cannot form or obtain enough fatty acids, amino acids, nucleotides, etc. to grow tall as there are just not enough of the macromolecules in their bodies to do so. David Shenk describes this when he says how “Mexicans ought to be tall and slender. Yet they’re so often stunted by poor diet and diseases that we assume they were born to be small” (Shenk 192). It is not a gene that Mexican people have, but a poor diet that leads to shortness. These observations show the interdependence of nature as it is because the environment in which these individuals live in that stunts their growth. The attributes that these individuals will obtain are shaped by how they interact with the world around them and if it is a challenge and an individual can only barely get by surviving than they will not grow tall as they do not have the macromolecules necessary to do so.
ReplyDeleteThe Middle Ages show a similar example of how the environment effects the traits a person exhibits. In the Middle Ages people were taller due to a warmer climate and with it the ability to grow more food. According to Rita Kennedy the heights of people in the Middle Ages was larger because of an “extending the growing period by up to four weeks each year and ensuring improved supplies of food. People also lived what we would consider very stationary lives, so outbreaks of communicable disease did not have the opportunity to spread over large areas” (Kennedy from http://www.livestrong.com/article/542877-the-average-height-of-humans-over-time/). This follows Shenk’s observations that Mexicans are generally shorter due to a poor diet and disease. When people are given the right environment they are able to take full advantage of their genes, just like how Shenk describes our true potential being way beyond what we think. Our potential for height is much greater than we think in many cases, and just as taller people were seen in the Middle Ages; people today are growing taller due to healthy diets and less risk of diseases. As the ability for people to obtain the correct nutrients grow we may even see a more rapid increase in height as time goes on unless the trend of keeping unhealthy diets starts to take effect first. Especially in the U.S. with much more processed food being developed we run into the danger that we will not obtain the nutrients we need while ironically being some of the first to have the ability to.
One way in which these relationships can further be studied is by comparing twins. Since identical twins have the same DNA, if height was completely controlled by genes, they would also have the same height. But we know that twins can do not necessarily need to be the same height and this is because they are exposed to different environments. This is similar to how two twins can have identical DNA but then have differences in their immune system as they have developed different acquired immunities due to different interactions with the environment and exposures to pathogens. Campbell mentions how “The name acquired reflects the fact that this immune response is enhanced by previous exposure to the infecting pathogen” (Campbell 930), explaining that no two peoples acquired immunity will be the same since no two people have been exposed to the exact same set of pathogens. The same goes for the environment in which we live in. No two people will receive the same exact macromolecules and therefore will not develop the same, even if they do happen to have the same DNA. This shows the theme of regulation in that our genes are constantly being regulated due to the changes in our environment that constantly happen around us. Enhancers in our DNA can get covered or histones methylated slightly changing what genes and the speed at which genes are being translated and transcribed at giving us different characteristics when exposed to different environments. David Shenk was right in calling our genes “volume knobs and switches. Think of a giant control board inside every cell of your body” (Shenk 19). There are constantly inputs put into this control board and thereby constant regulation to what genes are expressed and how frequently.
ReplyDelete-Kyle Nelson (kynels21@gmail.com)