*From a chemical point of view, proteins are by far the most structurally complex and functionally sophisticated molecules known.
Shuguang Zhang from MIT gave us an overall introduction to protein as the folding of the sequence of various amino acids. Especially, using the beautiful metaphor of architecture to describe the pattern in proteins. Thras karydis from DeepCure talked about the modern way to design a protein with computational tools.
And beef is composed of mainly the muscle of the cow. The central unit of muscle is the sarcomere, which mainly composed of myosin(~ 50 kDa) and actin(~41.8 kDa), an average of 45,000 kDa per protein. (26*5/45000)610^23 ~ 1.73 * 10^21 proteins in 500 grams of steak!
The genetic code is the universal language that relates base triplets in DNA to amino acids in proteins. All known organisms use the same triplet-amino acid equivalences, indicating that the divergence of the three branches of life (bacteria, archaea, and eukarya) evolved after the establishment of the code. It is reasonable to think that the current code grew from a simpler one, gradually incorporating new amino acids and assigning new codons to them (1). But this evolutionary track is lost, and we are left to wonder as to why the code includes only 20 amino acids.
The chirality in life is really mysterious. This phenomenon happend in chemicals, protein(often left), DNA and RNA, or even large scale that most human with right-handed. And DNA as double-strand helix also reveal this characteristics.
The origin of life is still a really hard but interesting question to chase after. DNA, RNA, and Amino acid, which one comes first? Maybe a pretty blurry or combination of the interaction between these things. Recommend one book called Protoceolls:Bridging Nonliving and Living Matter, published by MIT Press. It collected a series of articles on how the life begin and the possible evolution between nonliving and living. Amino acids are not only the buidling block of proteins and also maybe chemical messengers between cells. Before the existence of enzymes, scientists believed that amino acids can be produced by chemical synthesis.
Nucleosome act as the packaging unit for the DNA in eukaryotes. The basis of nucleosomes is composed of a consistent size DNA circulated around 8 histone proteins, about 146 base pairs. Digital databases also used certain kinds of methodology to compress and index data, which can reduce the data size and make it easy to read without searching all the data but just from the index.
Structure of the SARS-CoV-2 S protein. a Schematic representation of the SARS-CoV-2 spike. b–c The S protein RBD closed and opened status. d The S protein binds to ACE2 with opened RBD in the S1 subunit. e The six-helix structure formed by HR1 and HR2 of the S2 subunit.
