13 facts about genes | Mental Floss

In 2003, after 13 years of study, international researchers working on the revolutionary human genome project published their results. For the first time, the genetic components of the human being have been mapped, allowing researchers to "begin to understand a person's construction plan," according to the project's website. We now know that humans have between 20,000 and 25,000 genes, but researchers still have a lot to learn about these small segments of DNA. Below we have listed some facts about gene expression, genetic diseases and how genes make us who we are.

1. The word gene was not invented before the 20th century.

Although the "father of genetics" Gregor Mendel conducted his experiments on pea plants in the mid-1800s, it was not until 1909 that Danish botanist Wilhelm Johannsen became the first to describe the individual units of the inheritance of Mendel. He called them the genes-derived from pangenesis, the word used by Charles Darwin for his theory of heredity now refuted (Darwin, among other ideas, suggested that the acquired characteristics could be inherited).

2. At the genetic level, all humans are more than 99% identical.

Humans have much more in common than we might be inclined to believe. In fact, over 99% of our genes are exactly the same from one person to another. In other words, the diversity we observe in the human population, including characteristics such as eye color, size and blood group, is due to genetic differences of less than 1%. More specifically, variations of the same gene, called alleles, are responsible for these differences.

3. Genes can disappear or break as species evolve.

Thanks to a combination of genes, most mammals are able to produce their own vitamin C biologically internally, so to speak. However, during human history, we lost the ability to produce vitamin C when one of these genes stopped working in humans a long time ago. "You can see it in our genome. We're missing half of the gene, "said Mental Floss, Dr. Michael Jensen-Seaman, a genetic researcher and badociate professor of biological sciences at Duquesne University in Pittsburgh. "Generally, when a species loses a gene during its evolution, it's usually because it does not need it – and if you do not use it, you lose it. All our ancestors probably ate so much fruit that it was never necessary to make their own vitamin C. "Jensen-Seaman explained that humans had also lost hundreds of odor receptors (proteins produced by genes that detect specific odors), because we depend mainly on vision. This explains why our sense of smell is worse than many other species.

4. The large eyelashes of Elizabeth Taylor were probably due to a genetic mutation.

A mutation of the FOXC2 gene, aptly named, gave Elizabeth Taylor, the Hollywood icon, two rows of eyelashes. The technical term for this rare disorder is distichiasisand while this may seem like a desirable problem, there can be complications. According to the American Academy of Ophthalmology, this extra set of eyelashes is sometimes "fine and well tolerated", but in other cases it should be removed to prevent eye damage.

5. The genes involved in spermatozoa are among the most advanced genes in the animal kingdom.

In most of the natural world, a clbad of genes called sperm competition genes become better and better at fertilizing eggs. This is true for various species, including some primates and marine invertebrates. Consider primates as chimpanzees, whose females mate with several males in a short time. As a result, males compete at the genetic level – via their sperm – to breed offspring. "We believe that there is a kind of arms race among the genes involved in sperm production or in any aspect of male reproduction," says Jensen-Seaman. Essentially, the proteins in these genes change to help men rise to the challenge.

6. A "zombie gene" in elephants could help protect them from cancer.

In a 2018 study published in Cell reports, researchers at the University of Chicago have discovered that a copy of a cancer suppressor gene that was previously "dead" (or non-functional) in elephants had been reignited at some point. They do not know why or how it happened, but this revived "zombie gene" could explain why elephants have such a low cancer rate: only 5% die, compared to 11-25% of humans. Some have suggested that a drug could theoretically be created to mimic the function of this gene in order to treat cancer in humans.

7. Octopuses can edit their own genes.

Cephalopods, such as squid, cuttlefish and octopus, are incredibly clever and clever creatures, so much so that they can rewrite the genetic information contained in their neurons. Instead of a gene coding for a protein, which is normally the case, a process called recoding allows an octopus gene to produce several proteins. Scientists have discovered that this process is helping some Antarctic species "keep nerves afloat in icy waters" The Washington Post Notes.

8. The principle of the 1986 film Fly is not completely absurd.

After a failed experiment in FlyJeff Goldblum turns into a creature resembling a fly. Surprisingly, this premise could, um, fly – at least at some genetic level. Although different researchers have come up with different estimates, humans share about 52% of the same genes with fruit flies, and scientists estimate that this number is about the same for houseflies.

Could Jeff Goldblum theoretically turn into a human-fly hybrid if his genes were mingled with those of the insect in a futuristic teleportation device? Not exactly, but there are scientific parallels. "Thanks to genetic engineering, we can select genes and insert them into the genome of other organisms," says Erica Zahnle, DNA researcher, Chicago Tribune. "We do it all the time, right now there is a tomato hybrid that contains a fish gene."

9. Our genes could prevent us from living more than 125 years.

Despite advances in medicine, there may be a biological limit to how long humans can stay. Several studies suggest that we have already reached a peak, with a maximum for human life between 115 and 125 years old. According to this theory, cells can only replicate very often and often damage with age. Even if we are able to modify our genes by gene therapy, we probably will not be able to change them fast enough to make a difference, "said Judith Campisi of the Buck Institute for Research on Aging. L & # 39; Atlantic.

"For such reasons, it is pointless to claim that most humans will live in the near future of 200 to 500 years, thanks to medical or scientific progress, or that in 15 years we will add more than a year every year. the remaining life expectancy, "write the authors of a study of 2017 Frontiers in physiology, citing previous studies from 2003 and 2010, respectively. "Arousing false hopes without considering that human beings are already extremely" optimized "for their life seems inappropriate."

10. The idea that a single gene determines whether you have ear lobes attached or not is a myth.

Forget what you may have learned about ear lobes and genetics in college. While your genes probably play a role in determining the presence of attached ear lobes (a supposedly dominant trait) or unattached ear lobes, the idea that this trait is controlled by a single gene is simply wrong. In addition to this, the ear lobes do not even fall into two distinct categories. There is also a third, which John H. McDonald, badociate professor at the University of Delaware, calls intermediate ear lobes. "It does not seem to me that there are two categories, there is a continuous variation in the height of the point of attachment," McDonald writes on his website. A better example of trait controlled by a single gene is the blood group. Whether you have a blood group A, B or O is determined by three variations – or alleles – of a gene, according to Jensen-Seaman.

11. No, there is no "wanderlust gene" or "gene of music".

From time to time, new studies will appear suggesting a genetic source for various personality traits, preferences or talents. In 2015, there was talk of a "travel spirit gene" that inspires some people to travel, and several other reports suggest that musical aptitude is also inherited. However, like many things in science, the reality is not so simple. "Part of the problem is that when we are in school, we learn examples of traits controlled by a single gene, like Mendel's peas, and we start thinking that all variations are determined by one single gene ", Jensen-Seaman. said. "But apart from a variety of rare genetic diseases, most things interesting in medicine, in human behavior or in human variation, are what we call complex traits." These complex traits usually involve hundreds, even thousands, of genes, as well as the environmental factors to which you are exposed throughout your life.

12. DNA test kits can not tell you how smart you are.

Like your talents and personality, intelligence is also a complex trait that is difficult to measure because it is influenced by many different genes. A study conducted in 2017 identified 52 genes badociated with higher or lower intelligence, but the predictive power of these genes – or their ability to say how smart you are – is less than 5%. Another 2018 study identified 538 genes badociated with intelligence, which have a predictive power of 7%. In simple terms, no DNA test kit can accurately predict whether you are a genius or a dunce, even if the company claims it. And while scientists are improving this area of ​​study, DNA testing can not take into account environmental factors that also affect intelligence.

13. Your genetic background determines whether you think your pee smells like funky after eating asparagus.

Do you retreat from the smell of your urine after eating asparagus? If so, you are among the nearly 40% of people able to detect the smell of asparagus metabolized in the pee, according to a study published around 7,000 people of Euro-American descent. The bmjChristmas number 2016. (The bmj has an annual tradition of publishing strange and playful studies around this time of year, and the study of asparagus pee is no exception. The multiple olfactory receptor genes – and the 871 sequence variations on these genes – are involved in determining your talent for detecting asparagus asperges.