3.4: Very Basic Features of Life

There are two basic features of all Earth life (and we do not actually know any other Life):

1. Semi-permeable membranes:

   Most of living cells surrounded by oily cover which consists of two layers made of lipids and embedded there proteins. These membranes allow some molecules (e.g., gases or lipids) to go through, but most molecules only enter “with permission”, under the tight control of membrane proteins.

2. DNA \(\rightarrow\) RNA \(\rightarrow\) proteins:

   That sequence is called transcription (first arrow) and translation (second arrow). DNA stores information in form of nucleotide sequence, then fragments of DNA are copying into RNA (transcription). RNA, in turn, controls protein synthesis (translation). This is sometimes called the “central dogma of molecular biology”.

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