The cellular life cycle, also called the cell cycle, includes many processes necessary for successful self-replication. Beyond carrying out the tasks of routine metabolism, the cell must duplicate its components - most importantly, its genome - so that it can physically split into two complete daughter cells. The cell must also pass through a series of checkpoints that ensure conditions are favorable for division.
Cancer cells are hungry. To feed their rapid growth and division, their metabolism changes. Moreover, they use sugar (glucose) in a different way to normal cells. This animation, created by Nature Reviews Drug Discovery, explores the key aspects of the altered metabolism in cancer cells and explains how these can be exploited for the development of new anticancer strategies.
Aneuploidy-the incorrect number of chromosomes in a cell-is extremely common in early embryos and is the primary reason for pregnancy loss. A report published today (April 9) in Science reveals that one cause of this aneuploidy-aberrant cell divisions in the embryo-is linked to a genetic mutation carried by the mother. Astonishingly, this mutation turns out to be very common and appears to have been under positive selection during human evolution.
This case study synthesizes students' knowledge of the central dogma and cell structure by examining a rare health disorder in order to understand protein targeting and its medical consequences. Students first identify the molecular alteration in affected members of a family with renal Fanconi syndrome as reported in the New England Journal of Medicine (2014). Students then use an online bioinformatics tool to analyze the wildtype and mutant proteins and examine their subcellular localization. Finally, students use this information to explain the symptoms of affected family members. The case is delivered with a PowerPoint presentation that includes a selection of brainstorming prompts and "clicker questions." Students complete a worksheet (included in the teaching notes) before class, making the activity suitable for a flipped classroom. A second worksheet (also included in the teaching notes) is completed during class. The case is written for an introductory biology course for majors, but could also be used as a unit capstone in a non-majors human biology course; the case is also scalable to upper division courses in physiology that specifically explore kidney function.
"This modular case study tells the story of Dan and Annie, a married couple of Acadian ancestry who have a genetic form of deafblindness called Usher syndrome. They live in Southwest Louisiana, home of the largest population of DeafBlind citizens in the United States. Acadian Usher syndrome is caused by an allele of the USH1C gene that came to Louisiana with the first Acadian settlers from Canada who founded today's Cajun population. This allele's single nucleotide substitution creates an erroneous splice site that produces a defective cytoskeletal protein (harmonin) of the cochlear and vestibular hair cells and retinal photoreceptors. This splice site is the target of a promising gene therapy. The case study applies and connects Mendelian inheritance, chromosomes, cell division, vision and hearing, DNA sequences, gene expression, gene therapy and population genetics to a specific gene and its movement through generations of Dan and Annie's families. After the introduction, each of the remaining sections can be used independently either for in-class team activities or out-of-class extensions or assignments over an entire year of introductory undergraduate biology.
"
This case study challenges students to differentiate between anecdotal evidence and science-based evidence related to human health. The case uses a "flipped" approach in which students watch two preparatory videos prior to attending class. The first video defines anecdotal evidence while the second characterizes the different categories of scientific studies that generate evidence that is not anecdotal. Students watch the videos, analyze scenarios for anecdotal evidence, and think about what types of evidence they use to make health-related decisions. When students meet in class, they work in groups to compare and contrast these different categories of scientific studies and classify actual research studies aided by a dichotomous key for distinguishing between different types of studies related to human health. Primarily designed for students in introductory general biology courses, the activity could also be useful for lower division nutrition, physiology, or non-major biology courses or any course where students need to differentiate between science and pseudoscience.
This case study focuses on the intersection of defining a scientific species and defining a legal species. The compelling story of Lolita, an orca whale in captivity, is used to highlight the legal significance of species declaration. Students will work through scientific species definitions and data on Orca whales before deciding if Orca whales should be considered as one or several species. After an introduction to Lolita and a mock town hall meeting, students are thrown into the real life situation of contemplating the fate of an Orca in captivity that suddenly has protected legal status. This case was developed for use in a first-year biology course focusing on ecology, genetics, and evolution. It also could be used in upper or lower division courses on ecology, evolution, or conservation.
While the "vaccine controversy" has made headlines since the late 1990s, the emergence and popularity of social media has created a public opinion space bursting with pseudoscience, debatable claims and anecdotes regarding the value and importance of childhood vaccines. Because college students get a good deal of news and information from these resources, it is imperative that they distinguish science from pseudoscience and do not perpetuate rumor and falsehoods. In this case study, written for lower division non-science majors, students will view videos on the scientific method and a mock talk show, analyze data, and scrutinize social media posts. One of the takeaway points is that if a post/blog/interview identifies a victim, villain, and hero then the student should suspect a story grounded in belief involving pseudoscience. Following completion of the case, students will hopefully come to conclusions about vaccines based more in the realm of science rather than pseudoscience and continue to apply the scientific method when evaluating social media posts on other scientific topics.
This two-minute video provides brief background on the use of zebrafish as a model in studying animal development, before showing a time-lapse sequence of a fertilized zebrafish egg developing into a larva. The video includes some annotations that help orient the viewer during the time-lapse sequence. Teachers might want to mute the narration beginning at 0:42 min to avoid giving students too much information.
This phenomenon could stimulate the following driving questions:
How does the zebrafish develop from one cell to the many cells that make up the larva?
How do the zebrafish cells divide?
How are the developing zebrafish cells similar and different from each other?
If all cells in the zebrafish develop from the same original cell, then how do some cells develop differently than others?
How are cell division and growth related?
Squirrels are frequent and beloved residents of college campuses throughout the United States, but oftentimes less welcomed by campus maintenance officials who report squirrels nesting in buildings, interfering with airflow from heating and cooling units, and destroying gutters. In this laboratory case, students act as members of a fictitious "squirrel task force" appointed by their campus administrators to provide recommendations for how to manage their school's squirrel population. Students work in groups to assess the habitat suitability of their campus for squirrels by identifying and measuring trees that provide seasonal food for squirrels, and by identifying desirable hunting perches for common squirrel predators. Students conduct squirrel surveys in designated campus zones to calculate the number of squirrels per acre on their campus and compare it with mean squirrel densities reported in forested areas and at a rival institution. Students then compile and synthesize class data to provide management recommendations for university maintenance officials for either increasing or decreasing campus squirrel populations. Originally developed for an undergraduate wildlife biology course, the case could also be used in a lower-division biology or environmental studies course.
In this case study, students follow "Mr. Okoro" as he makes the long journey with his sick daughter "Ada" to seek medical attention at the nearest clinic in Enugu, Nigeria. It is the rainy season, and "Dr. Fabian" from the Division of Parasitic Diseases and Malaria has been called in to investigate a suspected outbreak of malaria. Students learn about the circumstances in Ada's background that may have led to her illness, and then adopt the perspective of Dr. Fabian as she investigates the outbreak. They consider the epidemiological triangle, the different stages of the Plasmodium parasite lifecycle and how it leads to malaria, and evaluate the broader societal factors and future implications of malaria in Sub-Saharan Africa. The case was designed for upper-level global health, public health, and human biology courses, but could also be adapted for general biology, health studies, infectious disease, and epidemiology courses.
Sulston worked alone, in silence, hunched over a microscope for eight hours a day. By studying and drawing worms of various ages, he figured out the ancestor and descendants of each of their cells. It was a monumental piece of science. Sulston mapped the complete history of an individual, the comprehensive family tree of a single body. "We had the entire story of the worm's cells from fertilized egg to adult," he later said, upon accepting the Nobel Prize for his work.