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1:30 animation As a human embryo develops, its cells become progressively restricted in the types of specialized cells that they can produce. Inner cell mass (ICM) cells of the blastocyst can make any type of body cell. Gastrula-stage cells can give rise to the cells of a given germ layer. Later, cells become even more restricted. For example, the pancreatic bud of the endoderm layer can only make the cells of the pancreas.

Amanda Briody describes two BioInteractive resources focused on Gorongosa National Park in Mozambique. She uses the short film "The Guide: A Biologist in Gorongosa" to introduce students to the park and its scientists. The Gorongosa Interactive Timeline allows her to ask data-based questions on the park's history and ecology, and have students make evidence-based claims.

A data collection and analysis lesson that examines selection for coat color in pocket mouse populations on different color substrates over time.

In their study of the medium ground finches, evolutionary biologists Peter and Rosemary Grant were able to track the evolution of beak size twice in an amazingly short period of time due to two major droughts that occurred in the 1970s and 1980s. This activity simulates the food availability during these droughts and demonstrates how rapidly natural selection can act when the environment changes. Students use two different types of tools to represent different beak types to see which is best adapted to collect and "eat" seeds of different sizes. Students collect and analyze data and draw conclusions about traits that offer a selective advantage under different environmental conditions. They have the option of using an Excel spreadsheet to calculate different descriptive statistics and interpret graphs.

Vibrio harveyi is a marine bacteria that emits light only at high population density. The bacterial bioluminescence is controlled by a system called quorum sensing. In this system, signaling molecules are secreted, and when they bind to cell surface receptors, they turn on many genes, including those that produce bioluminescence.

At first glance, the research of Bonnie Bassler and Baldomero "Toto" Olivera might not appear to be medical at all. Dr. Bassler works on marine bacteria that glow in the dark, while Dr. Olivera studies venomous snails that hunt by harpooning fish. Yet their findings show what science has revealed time and again-knowledge that can be used to unlock medical secrets is often hidden in unlikely places. Nature has much to teach us, as long as we know where to look and what to look for. Join us for a four-lecture series as Bonnie and Toto guide us through intriguing slices of the natural world revealing how a deeper understanding of nature and biodiversity informs their research into new medicines.

Components of the immune system called antibodies are found in the liquid portion of blood and help protect the body from harm. Antibodies can also be used outside the body in a laboratory-based assay to help diagnose disease caused by malfunctions of the immune system or by infections.

Transgenic organisms, which contain DNA that is inserted experimentally, are used to study many biological processes. In this lab, you will create a transgenic fly to study circadian rhythms.

The anole lizards of the Caribbean islands represent a group of about 150 closely related species, most of which evolved within the past 50 million years from a single colonizing species. Different processes, including geographic isolation, adaptation to different environments, and reproductive isolation, play a role in anole speciation. 

1 minute animated video

Are we witnessing a sixth mass extinction? What factors threaten ecosystems on land and in the sea? What are researchers doing to try to conserve biodiversity and ecosystems such as tigers in Asia and coral reefs around the world? What tools do we have to avoid a global catastrophe? In six half-hour lectures, three leading scientists describe the state of biodiversity on our planet and how to face the great challenges that lie ahead.

Corn was originally bred from the teosinte plant by native Mexican farmers. The morphologies of modern-day corn and teosinte plants are compared to illustrate how artificial selection can bring about dramatic changes in plants.

18 min video- Ten thousand years ago, corn didn't exist anywhere in the world, and until recently scientists argued vehemently about its origins. Today the crop is consumed voraciously by us, by our livestock, and as a major part of processed foods. So where did it come from? Popped Secret: The Mysterious Origin of Corn tells the story of the genetic changes involved in the transformation of a wild grass called teosinte into corn.  Evidence from genetics supports archeological findings pinpointing corn's origins to a very particular time and place in Mexico

Comparing features of a 4.4-million-year-old fossil skeleton to those of human and chimpanzee skeletons sheds light on our evolutionary history.

Taxonomy groups species by common traits. Modern taxonomy emphasizes evolutionary relatedness. Explore some principles of taxonomy by sorting twenty shells by their morphological characteristics. Whenever a pictorial index of shells appears, you can click on an image of a shell to open it in a separate window. There you can click and drag your mouse over the shell to rotate it for a more detailed examination. Additionally, you can use the small buttons in the lower right corner of the window to rotate the shell.

background for cone snail click and learn

The seashell phylogeny and evolution activity is an interactive online activity that can be done in class or assigned as homework. The Teacher's Guide describes supporting resources that can be used to teach students about seashells and a pre-activity exercise that uses the downloadable picture cards to familiarize students with the concept of sorting organisms.

This interactive explores different anatomical features of the human body and what they reveal about the evolutionary history we share with other organisms, including earlier, long-extinct species.

The virtual lab includes four modules that investigate different concepts in evolutionary biology, including adaptation, convergent evolution, phylogenetic analysis, reproductive isolation, and speciation. Each module involves data collection, calculations, analysis and answering questions. The "Educators" tab includes lists of key concepts and learning objectives and detailed suggestions for incorporating the lab in your instruction.

The Y chromosome is only one-third the size of the X. Although the Y has a partner in X, only the tips of these chromosomes are able to recombine. Thus, most of the Y chromosome is inherited from father to son in a pattern resembling asexual, not sexual, reproduction. No recombination means no reassortment, so deleterious mutations have no opportunity to be independently selected against. The Y chromosome therefore tends to accumulate changes and deletions faster than the X. Degradation doesn't occur in X chromosomes because during female meiosis, the X has the other X as a full partner in recombination.