BioNumbers - The Database of Useful Biological Numbers. Bio-Alive Biology and Life Science Video Share.
Classification. Animal Diversity Web. Tree of Life Web Project. The Tree of Life Web Project (ToL) is a collaborative effort of biologists and nature enthusiasts from around the world. On more than 10,000 World Wide Web pages, the project provides information about biodiversity, the characteristics of different groups of organisms, and their evolutionary history (phylogeny). Each page contains information about a particular group, e.g., salamanders, segmented worms, phlox flowers, tyrannosaurs, euglenids, Heliconius butterflies, club fungi, or the vampire squid.
ToL pages are linked one to another hierarchically, in the form of the evolutionary tree of life. Starting with the root of all Life on Earth and moving out along diverging branches to individual species, the structure of the ToL project thus illustrates the genetic connections between all living things.
Cracking the Code of Life | Watch the Program Here. Cracking the Code of Life PBS Airdate: April 17, 2001 ROBERT KRULWICH: When I look at this—and these are the three billion chemical letters, instructions for a human being—my eyes glaze over. But when scientist Eric Lander looks at this he sees stories. ERIC LANDER (Whitehead Institute/MIT): The genome is a storybook that's been edited for a couple billion years.
ROBERT KRULWICH: This is the story of one of the greatest scientific adventures ever, and at the heart of it is a small, very powerful molecule, DNA. For the past ten years, scientists all over the world have been painstakingly trying to read the tiny instructions buried inside our DNA. J. FRANCIS COLLINS (National Human Genome Research Institute): This is the ultimate imaginable thing that one could do scientifically...is to go and look at our own instruction book and then try to figure out what it's telling us.
ROBERT KRULWICH: And what it's telling us is so surprising and so strange and so unexpected. I'm Robert Krulwich. DR. Cell Size and Scale. Some cells are visible to the unaided eye The smallest objects that the unaided human eye can see are about 0.1 mm long. That means that under the right conditions, you might be able to see an ameoba proteus, a human egg, and a paramecium without using magnification. A magnifying glass can help you to see them more clearly, but they will still look tiny. Smaller cells are easily visible under a light microscope. It's even possible to make out structures within the cell, such as the nucleus, mitochondria and chloroplasts.
Light microscopes use a system of lenses to magnify an image. The power of a light microscope is limited by the wavelength of visible light, which is about 500 nm. To see anything smaller than 500 nm, you will need an electron microscope. Adenine The label on the nucleotide is not quite accurate. How can an X chromosome be nearly as big as the head of the sperm cell? No, this isn't a mistake. Carbon The size of the carbon atom is based on its van der Waals radius.
Human Body Systems | Human Organ Systems. Biology Content References.