BioQuakes

AP Biology class blog for discussing current research in Biology

Author: evalution

Leading Science with Light

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On March 8, 2021

In Student Post

Emmett Chappelle

Emmett Chappelle: The father of Bioluminescence

Emmett Chappelle was a African American Scientist and one who contributed greatly to Medicine, Philanthropy, and Astrochemistry. Chapelle was born on October 24, 1925 in Phoenix, Arizona where he grew up to attend Phoenix College. During his time at Phoenix college, he received an Associate’s Degree in electrical engineering and then a Bachelor’s of Science in biology at the University of California. Following, Emmett Chappelle taught biochemistry at Meharry Medical College. He received many offers for his graduate studies which he completed for his Master’s Degree at the University of Washington. Continuing his studies, Chappelle earned a Ph.D at Stanford University for 4 years before leaving for a research position at the Research Institute for Advanced Studies in Maryland. After years of hard work, he moved on to work at NASA before moving on to work at the Goddard Space Flight.

While at NASA, where Chappelle worked as a Exobiologist and Astrochemist, he made several discoveries. Perhaps the most important aspect of his work in the field of biology was his exploration of how light is given off by different organisms. Chappelle learned that certain chemicals give off light when mixed with living cells as long as adenosine triphosphate is present, and use this finding to detect bacteria in various samples, including bodily fluids, water, and other foods. Chappelle used this knowledge to develop a means to determine the health of plants. By measuring the amount of fluorescents emitted by plants in a forest, he was able to determine the amount of photosynthesis occurring within that forest. Chappelle’s study of the enzymes luciferin and luciferase, used by fireflies, to make their cells glow paved the path for many current scientists who still use these chemicals as florescent tags to see cancer cells.

firefly 8823 | common eastern (USA) firefly - photinus pyral… | Flickr

The glow created by Luciferin and Luciferase

Chappelle was inducted into the National Inventors Hall of Fame for his discoveries related to bioluminescence and the important roles they have played in many fields of science. Aside from his recognition for his scientific discoveries that earned him 14 US patents, Chappelle was also respected for his service in the United States Army and for the time he spent mentoring minority high school and college students. Although he passed away in October of 2019, Chappelle will long be remembered for his many contributions to science.

 

 

 

 

At the Coronavirus Drive-Thru: Which Test Would You Order?

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On January 18, 2021

In Student Post

As the world faces the Coronavirus pandemic testing has become a hot issue that people are facing in their daily lives.  But the question remains, which test is best?  It is likely that we will never know the answer to that question, but an understanding of the options available can certainly help the general public to make an informed decision before selecting a method of testing.  According to the article from the Financial Times, titled “What coronavirus test does the world need to track the pandemic?” there are two main types of tests for the virus officially named Sars-CoV-2: Antigen tests and Antibody tests. Antigen tests are used to detect whether or not an individual is infected with the coronavirus that causes Covid-19 while antibody tests are used to determine if an individual has been infected in the past.

Antigen tests come in two varieties, a rapid version that delivers results in minutes and another using Polymerase Chain Reaction (PCR) to multiply the genetic material found in a virus containing sample from an infected individual which takes longer.  Both the rapid and the PCR tests can be performed on a sample collected using a nasopharyngeal swab but can also be done using a throat swab or saliva sample.

Antigen Testing via Nasopharyngeal Swab

The virus can be detected as early a the first day of symptoms but is most accurate in the first week.  This is measured by the cycle threshold where the lower values indicate positive results.  No tests are always accurate but the rapid tests have been found to have more false positive and negative results than the PCR tests.  In a study performed by Vermont’s Department of Health only four individuals of 65 who had tested positive with the rapid test, also tested positive with the PCR test.  Because of this many states require both tests to confirm a positive diagnosis.  Unfortunately, the PCR tests have also shown high incidences of false negatives.  Regardless of which test is used, the accuracy still seems to be connected to the manufacturer of the test itself. Since the PCR test is thought to be the most accurate because it detects the presence of the genetic material of the virus, it is less likely to provide a false positive.  As result, these are best used to identify infection as opposed to letting an individual know that they are not infected.

Antibody tests require a blood sample in order to detect the presence of antibodies against Sars-CoV-2 because once an individual is infected with the virus their immune response creates IgM antibodies that are present close to the time of infection and IgG antibodies that are produced longer after infection.  These antibodies are proteins produced by the white blood cells that help to fight the virus, so if they are present in an antibody test, is clear that the individual has already been infected.  When an individual is infected with a virus, lymphocytes called B cells are triggered by the presence of the antigen of that virus, and bind to the antigen using an antigen receptor.  This then causes the production of cells that produce proteins called antibodies which have the same shape and structure as the antigen receptors of the B cells making them helpful in directly defending against antigens present in body fluids. Antibody tests provide a quick result and are preferred because they help people to determine if a person can return safely to society with less risk of infection.

As the pandemic became a global issue many tests began to be developed but the antigen tests were more commonly performed in the public while the antibody tests were reserved for private companies due to the need for more materials like swabs and reagents to perform the tests.  Both tests are being created all over the world but some countries are producing more than others and the US was slow to get started but has increased production more recently. Because the tests must be of good quality, and the staff that are using them must be trained well, it is hard to produce them fast enough.

 

Genes: They are influential in more ways than one

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On October 29, 2020

In Student Post

The article entitled, “Your Friends May Be In Your Genes,” discusses the study Virginia Commonwealth University researchers led on the influence of genes on the choices that we make when developing social connections.  Researchers claim that as people mature, their genes become progressively more critical in how they choose their friend groups. The discoveries in the study reflect which people are most susceptible for substance use or externalizing behaviors in their lifetime, based on the company they keep.

Comprised of individuals who were part of the Virginia Twin Registry, the study looked into the role of genetic factors in decision making amongst men during their adolescence, using roughly 1,800 male twin pairs ranging from teenage years to early adulthood, and involved interviews used to help explain how social groups can influence deviant behaviors.  Specifically, the study showed that genes can impact how individuals select their peer groups, and that those groups affects one’s tendency to engage in antisocial behaviors. Because peers have a significant effect on promoting and/or discouraging deviant behaviors and also oftentimes provide substances for abuse, an individual’s social environment can play a critical role in his/her life choices.

As mentioned in the article, “Why Twin Studies,” Twin studies have long been used as a means to identify different illnesses and disorders because they allow researchers to determine the the various influences on certain traits.  If a trait is similar between individuals who have the same genes, like identical twins, but not so in fraternal twins, a case can be made for a genetic link.  If a trait is similar between fraternal twins, but not so in identical twins, then a case can be made for environmental impact.

In the article, “Its Nature and Nurture: How Our Genes and Our Friends Shape the Way We Live Our Lives,” further support is given to the link between genes, environment, and risky behaviors when it points out that more educated Americans are less likely to smoke.  Since educated people tend to surround themselves with like minded people who find smoking unacceptable, those who are socially connected in this way are not usually smokers.  This suggests that people who have genes linked to educational success are less likely to have genes linked to smoking and vice versa.

Genes are segments of DNA that contain the instructions for the production of proteins.  Cells contain organelles, called ribosomes that are responsible for producing proteins that control physical traits.  Genes provide the information for which amino acids need to be joined to build each protein.

Personally, I think genes are interesting not only because they control the traits that we posses, but also because they can be linked to who we chose to surround ourselves with. It is our social choices that can then determine behaviors we participate in.

 

 

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