Created by Ryan Scott Patton.
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- I've heard phenyl-alanine is found in chocolate. Does this mean that people with phenylketonuria could never eat chocolate?(7 votes)
- There are two factors here: 1) can you get phenylalanine free chocolate and 2) can people with PKU ever eat phenylalanines?
1). Chocolate contains phenylalanine from two main sources: in the cocoa itself, and from the milk (protein component). I am sure someone has attempted to make chocolate with the phenylalanine removed for sufferers of PKU.
2) People with PKU need to avoid phenylalanine during development, so it does not affect the growth of their brain etc. Some adults revert to diets with phenylalanine in them once they leave teenage years. However, many of these PKU sufferers find that if they eat phenylalanine as adults, it affects concentration, memory etc (and often attempt to return to a phenylalanine free diet). I think whether PKU sufferers eat phenylalanine or not is more of a choice, once they are adults. (Pregnant women are the exception, as high phenylalanine levels in the mother lead to microcephaly, growth retardation etc). So, adults with PKU can choose to eat chocolate, if sticking to a phenylalanine diet isn't important to them, without immediate serious consequences.
Hope this helps :)(17 votes)
- How is "gene environment interaction" like epigenetics, or different from epigenetics?
- Gene environment interaction is different from epigenetics, because gene environment interaction deals with two different genotypes responding to environmental variation in different ways, while epigenetics is the study of changes in organisms caused by modification of gene expression. I hope this helps!
Misty (MM)(0 votes)
- Is there another video similar to this that explain genes and the environment in a simpler manner compared to the complex explanation made in this video? A video suited to students in year 9/10 plz!(5 votes)
- The three videos before this one talk all about genes and in a similar way. This video was more of an over view of them, or at least I thought so(0 votes)
- Do you believe you are who you are because of your upbringing or is it in your nature?(2 votes)
- I would like to make sure I understand the biological pathway that leads to PKU correctly. PAH gene (healthy)--> PAH enzyme--> converts phenylalanine to tyrosine---> continues metabolic pathway. PAH gene (mutated)--> PAH enzyme (missing a phenylalanine on its structure)--> cannot covert phenylalanine to tyrosine---> buildup of phenylalanine in the body--> hinders brain development. However, the environmental influence is because of the awareness of the severity and prevalence of the disease, int he US screenings for PKU have been implemented---> low phenylalanine diet---> healthy babies. However in a different environment without the resources or the knowledge to offer screening more babies would have adverse affects because of their PKU?(2 votes)
- How gene-environment interactions are critical for the expression of physical and psychological characteristics?(1 vote)
So the past videos of this series have been a pretty continuous discussion about our genes, so our genes and our environment related to our behavior. And to say that the genes and the environment are both important is really true. But really more specifically, they interact. And so I've alluded to this previously with the tea in the hot water example. But I'm going to get really specific with the language here because not only do our genes and our environment both effect our behavior, their effect is really dependent on each other. OK. So say you have two babies in a nursery of a hospital. One, we'll say, is genetically predisposed to be much more attractive than the other one. So we have this attractive baby and we have this really hideous baby. And as a result, the beautiful baby over here, it receives more affection and more attention. And it grows up to be generally more sociable and well adjusted. But suppose even further that at birth, both of these babies share a combination of genes that predisposes depression. As we've learned, the environment activates those genes. So in this case, maybe the genes are activated by environmental stressors. So both babies have these genes. But throughout life, this cute and ultra-lovable baby is surrounded by this great and supportive network and it has reduced stress. So its genes aren't stimulated to create the combination of neurotransmitters and other proteins that are involved in depression. But over here, this ugly baby is cranking out these proteins like crazy. And maybe that's because this baby is getting made fun of all the time or maybe it's because it has less friends. So I guess the cute baby's genes are somewhat responsible for setting up the environment. But really also the environment is responsible, at least to some degree, in keeping those depression genes at bay. Similarly, the less fortunate baby over here, his genes play a role in his tough life. And that tough life is activating the genes that are associated with creating the neurotransmitters of depression. So this is kind of a crude example of gene and environment interacting with each other. But a more specific example is the genetic condition PKU or phenylketonuria-- so PKU. And phenylketonuria is a genetic condition in humans that's caused by mutations to a gene that code for a liver enzyme. And that liver enzyme is phenylalanine hydroxylase-- so PAH. But because the enzyme is missing the amino acid phenylalanine, it doesn't get converted into the amino acid tyrosine during one of the metabolic pathways in our body. And so this causes a build-up of phenylalanine in the body, which can cause problems for brain development and even other problems. So PKU, it affects one in about 15,000 babies in the US. But most of these babies grow up without any major problems. And it turns out that during infant screening, these babies are identified and are placed on a special phenylalanine-free diet. So because they're not taking in all of this phenylalanine, it's resulting in a less problematic build up of the phenylalanine in the body. So it's really an interaction again between our genes and our environment that initiates the body's responses and behavior. So we see that the environment is dependent on genetic predisposition. But gene expression is also dependent on the environment. And this is the phenomenon that we're referring to as gene/environment interaction. So this idea is going to shift our vocabulary away from phrases like nature versus nurture. It's going to bring us to a more correct phraseology, nature through nurture.