The Tree of Life Gets a Makeover. Genetics and the tree of life. We traditionally think about the tree of life in terms of Kingdoms: plants, animals, fungi, bacteria, etc.
Genetics has really revolutionized the way we think about the tree of life and, because our classifications should reflect ancestry (that is, who is more closely related to whom), it has actually called into question a lot of our traditional classifications. Most biologists split up life into three domains: Archaea, Bacteria, and Eucarya (the last of which includes animals, plants, fungi, etc.). The three domains of life. From Carl Zimmer's blog The Loom. Science writer Carl Zimmer has an interesting post on his blog about how the newest genetic data may even call this classification into question by adding a fourth domain.
There’s a lot of debate about whether eukaryotes actually split off from within the archaea, or just branched off from a common ancestor. New research is looking at tons of genes from these sorts of organisms. References Wu, D., et al. (2011). Like this: The Timescale of Life. History of Life by Jesse Brunner on Prezi. Sedimentary rock, from Isua, Greenland, 3.7 billion years old showing chemical signature of life Graphite particles contain ratios of carbon isotopes that suggest they are derived from living cells.
From Rosing (1999) microscopic fossils in 3.26 billion-year old rocks from South Africa A spiny fossil from the Doushantuo Formation, China. This 590-million-year-old fossil represents either the preserved cell wall of a single-celled eukaryote, the reproductive cyst of a multicellular alga, or the egg case of an early animal. A structurally complex fossil from the Miroyedicha Formation, Siberia. This 850- to 950- million-year-old fossil is clearly eukaryotic Fossil cell from the Roper Group, Australia. This cell is 1.4 to 1.5 billion years old; it probably represents a eukaryote, but it lacks sufficient complexity for a definitive identification. 2-billion-year-old fossils from Michigan that paleontologists believe represent eukaryotic algae. History of Life on Earth by scott ketcham on Prezi. Transcript of History of Life on Earth Double click anywhere & add an idea Formation of Earth 4.5 Billion years ago 3.8 billion years first appearence of oceans on earth 2.2 Billion first photosynthetic cells 2.0 billion first eukaryotic cells 1.2 billion first multi-cellular eukaryotes 520 million first fish 420 million years first land plants 380 million first land animals 300 million first reptiles 200 million dinosaurs ruled the earth 170 million first birds 65 million dinosaurs go extinct mammals dominate 2 million first humans Earth December 7, 1972.
The History of Life on Earth by Robert Patierno on Prezi. The Earth is roughly 4.6 billion years old.
This timeline is scaled to show that life complex life as we know it is a realatively new development. Humans are only a dot on the timeline. Archaean Eon 4.6 billion years ago the earth was formed. This is the start of the Archaean Eon. 3.8 billion years ago we find the earliest rocks 3.5 billion years ago we find the earliet concrete evidence of life, fossiliezed stromatolites. These fossils are layered rocks that form when certain prokaryotes bind thin films of sediment together 2.7 billion years ago an oxygen revolution occured. The Cambrian Period showed the rise of many new animal Phyla. 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. To see anything smaller than 500 nm, you will need an electron microscope. How can an X chromosome be nearly as big as the head of the sperm cell? No, this isn't a mistake. The X chromosome is shown here in a condensed state, as it would appear in a cell that's going through mitosis. A chromosome is made up of genetic material (one long piece of DNA) wrapped around structural support proteins (histones).
Adenine The label on the nucleotide is not quite accurate. Carbon. Evolution – what next? BioNumbers - The Database of Useful Biological Numbers.