![The original role of proteins was to stabilize RNA, rather than to act as enzymes. (a) The peptidyl transferase center of the Escherichia coli ribosome [96]. The figure shows the RNA that forms the catalytic site, as identified by [97], with the three proteins that form the closest association with it: the large subunit proteins L2 (red), L4 (green) and L15 (magenta). All of these have substantial non-globular parts, which are the parts in contact with the RNA. The catalytic center is in the middle of the RNA helix. (b) The human 17S U2 snRNP involved in the first step of RNA splicing [98], showing the RNA core and the protein most closely associated with it (splicing factor 3b). Again, the part of the protein in contact with the RNA is lacking in regular secondary structure. -- LIFE via PubMed](https://i0.wp.com/astrobiology.com/wp-content/uploads/2025/06/Autocatalytic-Selection-As-A-Driver.png?resize=1200%2C720&ssl=1)
Darwin’s theory of evolution by natural selection was revolutionary because it provided a mechanism by which variation could be selected. This mechanism can only operate on living systems and thus […]
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Posted inAstrochemistry, Astrogeology, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Meteorites & Asteroids, Missions & Hardware, Planetary Protection & Biosafety, Sample Return, Status Report
Asteroid Bennu: Properties Of The Sample Collected By OSIRIS-REx
On September 24, 2023, NASA’s OSIRIS-REx mission dropped a capsule to Earth containing ~120 g of pristine carbonaceous regolith from Bennu. We describe the delivery and initial allocation of this asteroid […]
Posted inAstrochemistry, Astrogeology, Biosignatures & Paleobiology, Comets and Asteroids, Exploration Gear & Tech, Meteorites & Asteroids, Missions & Hardware, Sample Return, Status Report
Asteroid (101955) Bennu In The Laboratory: Properties Of The Sample Collected By OSIRIS-REx
On 24 September 2023, the NASA OSIRIS-REx mission dropped a capsule to Earth containing approximately 120 g of pristine carbonaceous regolith from Bennu.