Tuesday, March 12, 2013

CH5: The Power and The archives 1/2

Digital Information

A bit is a storage unit in a typical digital information system. Its value could be ‘0’ or ‘1’. A storage unit in genetic information system is a nucleotide, and its value ranges from ‘A’, ‘T’, ‘G’, to ‘C’. So each unit of storage can store four possible values. 

 Genetic Information

Polymerization is an act of joining polymers to create a very very long chain. When nucleotides are polymerized, the result is called ‘polynucleotides’. Living cells have two kind of polynucleotides: DNA and RNA. So DNA and RNA, or more broadly polynucleotides, are data structure capable of containing genetic information.
Our DNA and RNA are capable of storing staggering amount of information. But our body uses only 1% of DNA and RNA. To dates, nobody knows what the other 99% of DNA and RNA is for.


In a computer, ROM (Read Only Memory) is a type of memory that you can write to it once. Afterward, it can only be red. RAM (Random Access Memory), on the other hand, allows you to read and write to it as much as you want.

     In a biological cell, DNA is ROM. It is a program of how our body looks and operates. Like a computer program, it is written once when a cell is created. Afterwards, it will never change except for rare cases. If you are born with blue eyes, your eyes will be blue for the rest of your life. But it is red and copied to new cells when the cell multiplies.

Addresses and Contents

Every data structure is attributed by addresses and contents. You need to know ‘what’ (i.e., the content) you are storing. And, you need to know ‘where’ (i.e., the address) you store the content. This concept applies to both computer memory and our DNA. Every human has the same addressing space (i.e., the container), but we store different content in a particular location. That’s why we differ from each other. With generalization, we can say that every organism in the same species has the same addressing but each organism in the same species differs in what stored in each location.
Read/Write and Read-only Genetic Memory
In general, our DNA remains static. It changes mostly because of random error in copying (i.e., mutation). But, in a long term, the content stored in DNA can change to assists the chance of survival. Once in a blue moon, our addressing system changes too. An example is when we evolve from Chimpanzees which have 48 chromosomes. So at some point in time, we must have adopted a new addressing system with 46 chromosomes and have become humans as we know it today.

DNA and Its Ability to Preserve Information

DNA's performance as an archival medium is spectacular. It can be copied for 20 billion times down the generations without error.  To dates, even very advanced  information systems do not possess this high copying precision.
“A conservative estimate is that, in the absence of natural selection, DNA replicates so accurately that it takes five million replication generations to miscopy 1 per cent of the characters.”

The Aids of Natural Selection

DNA does not just preserve the information by not making any error in copying. It does so with the aids of natural selection. Sometimes error in copying can occur. We call this ‘mutation’. But if such mutation does not improve the rate of survival, the resulting genes will not be vertically transmitted into archival DNA.   From this argument, it is reasonable to assume that, at the beginning, we don’t have an eye. But better eyesight  helps us a little more in surviving. We gradually develop our eyes. Our eyesight become sharper though generation.  Up to some point, we can see sharper images and differentiate a tiger from a cat.
Despite the use of eyes as an example, the above fact is true for every organ such as ears, wings, venom glands. All organs evolve slowly. For example, 1% of hearing is better than no hearing at all, and 2% of hearing is better than 1% of hearing. The chance of survival increases continuously as each organ improves, no matter how small the change is. 
Book or Audiobooks?

Personally, I prefer audiobooks. It's fun, and I can listen when I'm doing something else. It also makes other activities (e.g., jogging) a lot more fun. For more detail about audiobooks, please read [this post].

There is one more reason that may encourage you to go for the audiobook version. You can get it now for FREE. Audible offers you a free trial for 14 days. Even if you get the book and cancel the subscription right away (so that you don't have to pay), you can keep the book. And, don't worry if you lost the audiobook file. Just log into audible.com. You can keep downloading the over and over again.
About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make  notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for.

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

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