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By Thomas Yuang Li, IV Form
The Evolution of Lactose Tolerance
Some people are lactose tolerant because they are lactase persistent (LP). Lactase is an enzyme responsible for the hydrolysis reaction or breakdown of lactose, the sugar in milk, and it helps human digest milk. LP is the continued activity of lactase in human adulthood. LP occurs because of the inheritance of genetic mutations that result in LP. It became prevalent in some societies due to evolution through natural selection. As of 2018, around 65% of the world population experienced lactose intolerance (NIH). The distribution gradient is uneven, for about 90% of the population in East Asia are lactose intolerant while about only 10% of the population in North Western Europe are lactose intolerant.
Lactose is a disaccharide that contains a galactose and a glucose unit. Lactose makes up 6-8% of milk. Humans can only digest lactose with the help of lactase, making lactase critical in the digestion of milk. Lactase is produced by small intestine cells. It accelerates the hydrolysis reaction or breakdown of lactose. Through hydrolysis, lactose is broken down into glucose and galactose, which are monosaccharides, or simple sugar molecules, that can be absorbed into the human bloodstream. Lactase catalyzes this hydrolysis reaction by lowering the activation energy, the minimum energy required to initiate a chemical reaction. Without sufficient lactase, humans cannot fully digest lactose. As shown in Figure 1, the undigested lactose then passes on to the large intestine, where it interacts with bacteria and ferments. The fermentation causes symptoms of lactose intolerance, which range from bloating to diarrhea.(more…)
By Jiwon Choi, VI Form
Editor’s Note: This STEM Fellowship project by Jiwon won the Worcester Regional Science and Engineering Fair (1st out of 130+ students). She placed third out of all 200+ projects at the Massachusetts Science and Engineering Fair allowing her to compete at 2019 ISEF in Phoenix.
Three-dimensional (3D) bioprinting is one of the most promising methods of tissue engineering as it provides unprecedented versatility and precision in delivering cells and biomaterials to desirable places. However, limitations still exist in the availability of bioinks with natural bio-macromolecular components. In this research, chicken albumin is evaluated as a potential bioink for direct extrusion bioprinting of hollow constructs through alginate-templated crosslinking. Channel diameter, wall thickness, and bioink feed rates are calculated to assess the printing performance of the alginate-based bioink. It is shown that an albumin-based bioink with as low as 1.33% of total alginate concentration can be employed to successfully print microfibrous hollow constructs with a uniform diameter.
By Clara Hua, IV Form
Annotated Diagram: Human Immunodeficiency Virus
Editor’s Note: The “Biology 30” class zoomed in to examine the cellular (and sub-cellular) impacts and zoomed out to consider some of the economic, geo-political, environmental and cultural factors that have an influence on the spread of this disease. An Annotated Diagram is a formal sketchnote that aims to demonstrate understanding of the information by presenting how the information (the full story of HIV/AIDS) was processed.
By Matt Walsh, VI Form, Laura Sabino, V Form, and Maddie Wass, V Form
Mitotic Cell Division Artifact of Learning
Editor’s Note: See the image below of the whiteboard artifact images for the description of the assignment in Advanced Biology.
By Samantha Wang, IV Form
International Brain Bee Neuroscience Competition
What is Brain Bee?
Brain Bee is a neuroscience competition for teenagers from around the world. The initiative of this competition, according to its founder Dr. Norbert Myslinski, is to find better solutions for brain disorders. Every year, Brain Bee is first held at the state level. Winners of each state then compete in the country’s Regional Brain Bee, and one representative from each Regional Brain Bee will be sent to the International Brain Bee World Championship. This competition assigns a variety of tasks to its participants. The first part of the Brain Bee is to answer multiple-choice questions, which have around thirty questions about either the brain’s structure and function or pathology and treatment of brain disorders. Participants are then given brain models, where they are asked to distinguish parts of a brain and state the functions they perform. The last part involves the most interesting task I have ever experienced in any competition: four “patients” with different brain disorders, with acting from the volunteers of the organization, tell the specific life experience with their diseases. The participants are asked to diagnose their neurological or psychiatric conditions. (more…)