Enzymes are proteins or RNA that catalyze (i.e. accelerate) chemical reactions. Enzymes are biochemical catalysts. In these reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts these into different set of molecule(s), the product(s). Almost all processes in the cell need enzymes in order to occur at significant rates. Since enzymes are extremely selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines the biochemistry and signal transduction that occur in a cell.

Overview of C4 carbon fixation, one of three biochemical mechanisms, along with C3 and CAM photosynthesis, functioning in land plants to "fix" carbon dioxide (binding the gaseous molecules to dissolved compounds inside the plant) for sugar production through photosynthesis.

Rosalind Elsie Franklin (25 July 1920 – 16 April 1958) was an English physical chemist and crystallographer who made important contributions to the understanding of the fine structures of DNA, viruses, coal and graphite. Franklin is best known for her contribution to the discovery of the structure of DNA in 1953. In the years following, she led pioneering work on the tobacco mosaic and polio viruses. She died in 1958 of ovarian cancer.

• ...that a Ribozyme is an RNA molecule that can catalyze a chemical reaction just like enzymes and may pre-date them?


• ...that several groups have managed to add non-natural bases to DNA, while others have added non-natural amino acids into the genetic code?


• ...that Deinococcus radiodurans is one of the most radioresistant organisms known, while some fungi survive by harnessing the energy from radiation?


• ...that the cytoskeleton of a cell acts like a tensegrity model [1], such that a cell can resist shear, compression and tension?


• ...that eggs laid by the Ostrich can weigh 1.3 kg and the contained yolk is the largest single cell of any organism?


• ...that Red blood cells have an average life span of 120 days?


• ...that Red blood cells do not contain the genetic material needed to synthesize new proteins or undergo cell division?


• ...that Robert Hooke coined the biological term cell -- so called because his observations of plant cells reminded him of monks' cells which were called "cellula"?

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