What do you think?
Rate this book
The Code of Life
The authors of more than twenty science books for children, the Silversteins here clearly and concisely present a fascinating, but intricate, subject to middle-school-aged youngsters. In this case, they describe how DNA works, how a human cell forms, what happens when "the code" goes wrong, and related topics. This book makes "students aware of an important and exciting field of research and its possible impact on all our lives" — Library Journal .
- GenresScience
96 pages, Paperback
First published January 1, 1976
2 people want to read
About the author
Alvin Silverstein
262 books7 followersAlvin Silverstein grew up in Brooklyn, the youngest son of an immigrant family who emphasized hard work and education. After graduating from Brooklyn College, he went to graduate school at the University of Pennsylvania, where he got a Master's degree in chemistry and met his wife, author Virginia B. Silverstein. He got his Ph.D. at NYU while teaching at the College of Staten Island. He ultimately became a Professor of Biology there and also Director of the Physician Assistant program, while coauthoring books with his wife and, later, two of their children as well.
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
Displaying 1 of 1 review
Read
November 10, 2016Tiny DNA contains the full information to produce a human from the first cell. A DNA is like a code book written in an alphabet of size 4. Each of the letters is actually a chemical molecule, one of the four organic bases: Adenine (A), Guanine (G), Thymine (T), and Cytosine (C). These bases come in pairs: A paired with T and G paired with C. A DNA molecule, though tiny, can have billions such letters. So, the number of possible strings is 4^(1 billion) -- huge enough to cover all the varied life forms.
The body acts through another molecule called protein, which has amino-acids as its building block. There are 20 amino acids, so to implement its code DNA must translate a 4-alphabet code to a 20-alphabet code. Clearly, more than one letter in DNA must be mapped to a single letter in the protein. If we take 2 DNA letters then the number of possibilities is 4*4= 16, so that is not enough to cover all 20 kinds of amino acids. So, 3 DNA letters are needed to represent one protein letter. And that is what nature chose, not more.
DNA itself cannot do this 4-to-20 translation. DNA produces messenger RNA which is a copy of it except T is replaced with U (Uracil). Messenger RNA goes out of the nucleus to a ball like structure called Ribosome, there it waits. There is another RNA called transfer RNA which has one end like 3-DNA letter holder and the other end attached to a particular amino acid. This transfer RNA comes to Ribosome and attaches to the correct place of the messenger RNA, so we have gotten one 4-to-20 translation and the result is one amino acid; another transfer RNA comes, and we get another amino acid, and so on. The Ribosome thus slides along the messenger RNA and falls off when all the amino acids are joined in a chain to produce the right protein. Through painstaking experiments we have created the table which maps which 3-letters of DNA map to which amino acid. There are even 3-letter sequences which act as start and stop signals; using those a single messenger RNA can act as a template for producing more than one proteins.
DNA and this rigmarole are common across all life forms, which might make you think that all of us, the living things, have a common ancestor.
Now, the unit of heredity is not the DNA but a part of it (say a thousand letters) which we call "gene" -- a rather less defined term; like there is a gene for blond hair or a gene for tallness. In humans, we have 23 pairs of chromosomes. Most genes (DNA is contained in chromosome, and a gene is a part of DNA) are paired as well. Half of a pair comes from the father, and another half comes from the mother. One of this (father's or mother's gene) can be dominant so that the other one does not get expressed. For example, the gene for brown hair is dominant over blond hair; so if a baby has brown-blond gene pair, then it will get brown color, the only way it can get blond hair is if both genes are blond.
The body acts through another molecule called protein, which has amino-acids as its building block. There are 20 amino acids, so to implement its code DNA must translate a 4-alphabet code to a 20-alphabet code. Clearly, more than one letter in DNA must be mapped to a single letter in the protein. If we take 2 DNA letters then the number of possibilities is 4*4= 16, so that is not enough to cover all 20 kinds of amino acids. So, 3 DNA letters are needed to represent one protein letter. And that is what nature chose, not more.
DNA itself cannot do this 4-to-20 translation. DNA produces messenger RNA which is a copy of it except T is replaced with U (Uracil). Messenger RNA goes out of the nucleus to a ball like structure called Ribosome, there it waits. There is another RNA called transfer RNA which has one end like 3-DNA letter holder and the other end attached to a particular amino acid. This transfer RNA comes to Ribosome and attaches to the correct place of the messenger RNA, so we have gotten one 4-to-20 translation and the result is one amino acid; another transfer RNA comes, and we get another amino acid, and so on. The Ribosome thus slides along the messenger RNA and falls off when all the amino acids are joined in a chain to produce the right protein. Through painstaking experiments we have created the table which maps which 3-letters of DNA map to which amino acid. There are even 3-letter sequences which act as start and stop signals; using those a single messenger RNA can act as a template for producing more than one proteins.
DNA and this rigmarole are common across all life forms, which might make you think that all of us, the living things, have a common ancestor.
Now, the unit of heredity is not the DNA but a part of it (say a thousand letters) which we call "gene" -- a rather less defined term; like there is a gene for blond hair or a gene for tallness. In humans, we have 23 pairs of chromosomes. Most genes (DNA is contained in chromosome, and a gene is a part of DNA) are paired as well. Half of a pair comes from the father, and another half comes from the mother. One of this (father's or mother's gene) can be dominant so that the other one does not get expressed. For example, the gene for brown hair is dominant over blond hair; so if a baby has brown-blond gene pair, then it will get brown color, the only way it can get blond hair is if both genes are blond.
Displaying 1 of 1 review