Fossil Friday: Oldest fossils on earth!

Modern day stromatolites in Sharks Bay, Australia Welcome back to Fossil Friday.  Today I’m linking to a 2013 article in LiveScience, that reports on 3.5 billion year old fossil bacteria.  These Australian fossils are among the oldest fossils yet discovered.  In life, they seem to have existed in shallow waters and may have been a variety of photosynthetic bacteria.  Not only did life arise very early in the history of our planet, but oxygen producing organisms appear to have gotten their start very early, as well.  The bacteria are visible as fossils because they form structures called stromatolites.  There are still bacterial stromatolites alive today in Australia.  They were probably common in the early oceans, but rare now due to predators that would easily gobble them up! Oldest Fossils on Earth

Atomic Tuesday: The Leptons

The Lepton Family by Rich Feldenberg The leptons are a family of elementary particles that have characteristic properties.  They have a value of quantum angular momentum, known as spin that is always a 1/2 integer value.  They also have an electric charge (minus for normal matter leptons and positive for anti-matter leptons).  Leptons are not effected by the strong nuclear force so are not bound to atomic nuclei in the way Up and Down quarks can be.  The most familiar of the leptons is the electron.  The electron is common and is bound to atoms through its electromagnetic attraction to the positive charge in the nucleus.  There are two heavier versions of leptons called the muon and the tau.  The muon and tau are considered electron-like neutrinos, since they are identical to electrons in every way except for their mass. In contrast to the electron-like leptons, there are neutral-leptons called neutrinos.  They come in different varieties and there is one variety associated with

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Mutation Monday (Your Mutation Station): Thymine dimers

by Rich Feldenberg Welcome back to your mutation station.  Today we’ll look at a harmful effect on your DNA due to ultraviolet light, which leads to dimerization of the nucleotide bases thymine (T).  If there are two T bases next to each other in the DNA strand and they absorb UV light they can undergo a photochemical reaction that causes them to link-up.   The double bonds in the base break and then form single bonds to their neighbor. This blocks normal base pairing on to the other DNA strand of the double helix, and results in a mutation.  Fortunately there are cellular repair mechanisms that can find and fix these errors, but some errors escape detection and cause major harm.  Some melanomas are thought to be due to thyimine dimers caused by the effect of UV sunlight. Thymine dimers are actually a more specific form of what is called pyrimidine dimers.  The bases thymine and cytosine (T and C)

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