4 ms·

Well OK it spirals around, but isn't RNA/DNA really just linear? To access, you need an enzyme to walk it forwards or backwards and there are no other options t

by delibes 10y ago

Well OK it spirals around, but isn't RNA/DNA really just linear? To access, you need an enzyme to walk it forwards or backwards and there are no other options that I know of. (I'm not a biologist)

mcarlise 10y ago
> but isn't RNA/DNA really just linear No, it's not. RNA/DNA contains 4D of information. You need hundreds of proteins (also to be clear not enzymes - all enzymes are proteins, not all proteins are enzymes). Additionally (along with proteins), you need to unpack the chromatin structures - which requires huge cellular state transitions (hence the 4th dimension). So what bases are available to be replicated (read?) is dependent on the chromatin structure and their current state (euchromatin/heterochromatin), then depending on local molecular concentrations, replication is dependented on what proteins are locally available (due to the nucleosome structure). This is the very essence to why a large number of traits and diseases do not follow mendelian inheritance.
- dekhn 10y ago
  More likely, complex traits are influenced by gene regulation, which is affected by chromatin structure, but chromatin is just one form of regulation. Complex traits are more likely just due to many interaction elements (promoters, enhancers affecting multiple genes in a nonlinear way) and the complex feedback mechanisms and redundancy mechanisms. Chromatin state is completely abolished and recovered (in a non-deterministic way) in egg and sperm, which places some limits on which it can influence inheritence.
saiya-jin 10y ago
yeah it's 1-dimensional and processing I know about is sequential, twist is there just to make it more flexible inside the cell similar to old telephone cord (something about putting 3-meter line into few tens of micrometer sized cell)
dekhn 10y ago
My point is that while DNA is linear, using 3D structure makes packing density far higher.

by delibes 10y ago

Well OK it spirals around, but isn't RNA/DNA really just linear? To access, you need an enzyme to walk it forwards or backwards and there are no other options that I know of. (I'm not a biologist)

mcarlise 10y ago

> but isn't RNA/DNA really just linear No, it's not. RNA/DNA contains 4D of information. You need hundreds of proteins (also to be clear not enzymes - all enzymes are proteins, not all proteins are enzymes). Additionally (along with proteins), you need to unpack the chromatin structures - which requires huge cellular state transitions (hence the 4th dimension). So what bases are available to be replicated (read?) is dependent on the chromatin structure and their current state (euchromatin/heterochromatin), then depending on local molecular concentrations, replication is dependented on what proteins are locally available (due to the nucleosome structure). This is the very essence to why a large number of traits and diseases do not follow mendelian inheritance.

dekhn 10y ago
More likely, complex traits are influenced by gene regulation, which is affected by chromatin structure, but chromatin is just one form of regulation. Complex traits are more likely just due to many interaction elements (promoters, enhancers affecting multiple genes in a nonlinear way) and the complex feedback mechanisms and redundancy mechanisms. Chromatin state is completely abolished and recovered (in a non-deterministic way) in egg and sperm, which places some limits on which it can influence inheritence.

saiya-jin 10y ago

yeah it's 1-dimensional and processing I know about is sequential, twist is there just to make it more flexible inside the cell similar to old telephone cord (something about putting 3-meter line into few tens of micrometer sized cell)

dekhn 10y ago

My point is that while DNA is linear, using 3D structure makes packing density far higher.