Posts by Alex
Okay, so this title clearly requires a bit of context but don’t worry it all comes together in the end. Let’s start by talking about GMOs. Yikes. But what exactly is a GMO? Dubbed as “Frankenfood” it undoubtedly has a negative reputation among most today. But what is it that incites so much fear in us about the idea of “genetic modification”?
Let’s face it: Colorado tomatoes are nothing to ride home about. That’s probably because they’re from Florida, or California and have been picked while they’re still green so they don’t over ripen on the truck ride to Colorado Springs. But being picked so early has its downfalls; theses premature tomatoes have failed to receive nutrients and proteins that make them flavorful.
At one point, scientists had proposed a clever way to resolve this problem. Let’s examine some background information first. DNA is transcribed into mRNA, which is translated into proteins, which perform a myriad of functions in cells. A long time ago it was discovered that plants had a pretty nifty defense mechanism against viruses: they are able to recognize double stranded RNA viruses and target them for destruction. Back to our tomato situation: fruit ripens due to a gene coding for the expression of ethylene. When you put a pre-ripe fruit next to a banana to ripen, it’s because the ethylene secreted by the banana will stimulate ripening. Scientists figured that if they could somehow slow down the expression of the ethylene gene in a tomato, it would slow ripening. This would allow tomatoes to be picked when they were riper and not over ripen before reaching the store. After the tomato transcribes the ethylene DNA into mRNA scientists engineered the tomato to make another mRNA from the same gene that would bind to the first mRNA. What do we get? Double stranded RNA, which will be seen as a virus and degraded. Bottom line? Less mRNA means less ethylene protein translated: slower ripening.
This idea seems pretty clever, plausible, and benign. Yet it was not taken quite as well. Double stranded RNA? They’ve put a virus in a tomato. HIV is an RNA virus right? Does this tomato have HIV?
Now I’m not saying all GMOs are completely harmless but I think it’s important to understand what something actual is before forming a definitive opinion. I guess my point is that GMOs and non-GMOs aren’t necessarily antitheses…maybe more like tom-A-to tom-AH-to.
While it seems logical to think that gene expression is a fixed, unchanging thing, like the Rosetta Stone of human biology this isn’t necessarily the case. Genes are often viewed as sequences written into our DNA that remain unaltered through our lives, yet today we spent the majority of class time disproving this idea.
As it turns out gene expression can be influenced by many factors, one of the main being one’s environment. Different stimulus in our surroundings can have a great impact on our genes such as causing one section of the genome with specific genes to be replicated multiple times, a phenomenon known as gene amplification. Think of it as a supply and demand type situation. Genes code for proteins, which perform specialized functions; as the need for a protein goes up, our bodies respond by supplying more copies of the corresponding gene. For example, when small mammals are exposed to heavy metal (not just the headbanging kind) there is a significant increase in replication of a gene coding for a particular protein that will remove metal from the bloodstream. Conversely, sometimes it may be desirable to prevent gene amplification. Take chemotherapy as an example. Chemotherapy is generally given in large doses. This helps to prevent cancer cells from undergoing gene amplification and subsequently being able to protect themselves from treatments aimed to destroy them.
So at this point in class we’ve firmly established that gene expression is malleable. But how does this idea apply to things that are more relevant to the general population (i.e. something other than disease treatment or metal exposure)? Well there’s another mechanism in the cell that can result in the generation of genetic material, a process called gene duplication. When there are multiple copies of the same gene this means that one copy could theoretically develop a mutation and the cell would still have one functional copy. As it turns out this is one way in which new genes come onto the playing field. It’s kind of like if you have your best player bat cleanup so top of the line you have more room to experiment.
Needless to say, by now I’ve become more than convinced of the incredibly adaptable nature of gene expression. Maybe if the human genome is anything like the Rosetta Stone it at least has some extra carving space and an eraser.
Imagine a stack of textbooks, packed like sardines with words, and standing four stories high. Now think about being given the task to find not one page, not one paragraph, but one word. Seems like an impossible task. To some extent, this is comparable to the task scientists were charged with in the late 1980s while attempting to pinpoint the location of a mutant gene responsible for causing cystic fibrosis. When I initially heard this daunting analogy I could scarcely imagine any way in which one could accomplish this job. And yet in three hours, minus time for water and snacks, our professor was able to give us a pretty good idea.
Our DNA is made up of different bases abbreviated with letters, which are wound around proteins that make up structures called chromosomes. And incredibly, some three billion letters are all able to fit into 23 pairs of chromosomes, which reside happily in the cell of each nucleus in each cell. I find sometimes in class as we work through problems, attack complex scenarios, and delve deep into peculiar topics it’s easy to get caught up in minute details that demand your attention and forget the sheer vastness and breadth of genetics. But when I take a step back it’s pretty astonishing to me, even as a science major, that genetics can weave its way into nearly any subject imaginable. And I guess that’s obvious, I mean biology is the study of life after all, but its scope and relevance is pretty impressive.
It’s T-minus 5 minutes to the start of class and I’m anxiously filtering through yesterday’s information trying to make room for today’s. Class typically begins at 9:00 am and lasts until lunchtime. Rather than watching slides on a PowerPoint or reading from a textbook our professor engages us in often seemingly different topics which somehow always manage to come down to one thing: the gene, a pair of genes, or some combination of genes. From hypercholesterolemia to baldness to chocolate and yellow labs I usually manage to leave class with more questions that I came in with. But one week in and I’m trying to accept that maybe that’s the whole idea of genetics: to realize how much there is and how much is still widely unknown.