BioQuakes

AP Biology class blog for discussing current research in Biology

Author: cytoplasam

Testing For The Virus That Changed Our Lives

SARS-CoV-2, the virus that causes the COVID-19 disease, has changed our daily lives completely. Doctors and researchers have been working endlessly to figure out how to put a stop to its spread and get us back to our normal ways of life. Getting tested for COVID-19 is an extremely helpful way to further our knowledge of the virus and prevent it from spreading.

In order to prevent the spread of the virus, we must be able to track it. Researchers have found a way to test for COVID-19 through diagnostic tests. The tests are performed by healthcare personnels at clinics or doctors’ offices, with specific kits. The head is tilted back at a 70 degree angle and a swab is inserted inside the nostril, sometimes both, to collect the cells from the back of the nose. The swab is inserted to absorb the cells and then put into a sterile tube to be sent to a laboratory. There, a PCR test is performed and the cells are examined.

You might ask, “how does the test work?” In simple terms, the virus’ RNA is made up of thousands of nucleotides. Researchers have developed a PCR test, in which it looks for the virus’ DNA, within a person’s cells. Since the virus does not have DNA but rather has RNA, a RT-PCR test is needed to test for the disease. The RT-PCR test consists of various “reverse transcription polymerase chain reactions” where the RNA of the virus is transcribed into “complimentary DNA” that is used in the PCR test. The nucleic acids of a person’s cells are taken from the swab they were tested with, and replicated millions of times to be examined. The DNA is processed by a PCR instrument to see if the genes of the virus is within the human cell. 

SARS-CoV-2 has a surface made up of spike proteins. The spike proteins attach to a receptor on the surface of a human cell and fuses through the membrane. This is how it passes through its first line of defenses and enters respiratory epithelial cells lined on the respiratory tract, making it a respiratory virus. Once the virus is inside of the cell, it releases its RNA and is encoded, thus replicating itself. From there, the dendritic cells work to get a defense reaction from the immune system. 

When the pandemic had recently started, there were very limited tests available. The CDC, Center for Disease Control and Prevention, urged that only people with symptoms or people who have had high exposure to a person who tested positive be tested. Symptoms include a dry cough, fever, and shortness of breath. It was later found that people were testing positive for COVID-19 who had no symptoms, or had high exposure to it. This pushed researchers to develop more tests due to the fact that the virus was spread easier than they initially thought. Now there have been millions of tests shipped out, and more people are able to get tested. This is prevents the virus from spreading through people who do not know they have it. It also allows researchers to get a more accurate number of positive cases. The development of test kits and PCR testing has been extremely successful, even though there have been some inaccurate results. 

When do you think we will be able to return to our normal lives?

The Evolution Of The Largest Animal On Earth

How did Blue Whales get to be as big as they are today? The answer lies in the understanding of evolution and adaptation.

In the past, Baleen whales had a diet fully consisting of plankton that rose to the ocean’s surface. About 5 million years ago, Rorqual whales started to adapt more to their environments, and were able to find that “lunge feeding” was the most efficient way to obtain their food and grow. This new finding lead their diet to change from plankton to krill and small fish. Lunge feeding and upwelling exposed them to a larger availably of food, which ultimalelty caused whales to evolve and have bigger mouths. Through wind motions, upwelling was able to occur, and rich nutrients were brought up from the depths of the ocean, which stimulated “growth and reproduction.” With their bigger mouths, came their bigger bodies, but of course it is not that simple. The evolution of whales can not be fully explained without evolutionary ecology. As whales continue to grow and evolve, their DNA gradually begins to change to continue to allow the whale to survive. The DNA begins to give it different instructions based on their new adaptations.

To get a deeper look into DNA, we can look at nucleic acids. Nucleic acids are the building blocks of DNA molecules. Phosphodiester bonds connect the phosphate and sugar groups of nucleotides, monomers of nucleic acids, to make up the double helices of DNA. A whale’s DNA is quickly evolving and forces the DNA to adjust and change the functions in the whale by changing the order of the bases, adenine, guanine, cytosine, and thymine, that it is made up of.

Whales had to adapt and conquer. The ocean is filled with competition and every animal has to do what they need to survive. Specialization comes into play when there are many animals going for the same foods. Specializing on one specific prey gives the predator an advantage against other predators. Blue Whales specialized in krill, but as whales soon came to find out, krill is not an easy prey to catch. A krill’s ideal environment is a polar ocean with upwelling zones, so in order for whales to catch their food, they must be able to be mobile and quick. Their bodies have adapted to being able to move very fluidly through the ocean and catch their prey with speed and an “element of surprise.”

With environmental problems quickly rising, whales are going to face challenges. Climate change is heating up the oceans and causing a decrease in krill and plankton. Whales’ specialization is going to play a crucial role in not letting them die out. Since they have focused their evolution on eating krill, they will have to adapt to the decrease in availability.

 

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