ReCharde Johnson
Professor
Grymes
NCLC
120
Learning Log 3:
Immortal Genes
Synopsis
In the
third chapter of the novel The Making of the Fittest by Sean Carroll we
are introduced to immortal genes, which are powerful genealogical records that
reflect the degree of relatedness among kingdoms and help us retrieve and
reconstruct events in the history of life that are not visible in the fossil
record. Through studying these immortal genes, scientist Tom Brock was able to
find a new division of life, which is now referred to as the Archea. Scrutiny
of Archean genes has revealed critical clues about the making of our own
eukaryotic ancestors nearly 2 billion years ago. Many pieces of human DNA codes
are preserved in the DNA of these primitive organisms. These shared texts forms
the remaining traces of an early event that gave rise to the first eukaryote,
and is crucial evidence that an archean was one of our original genetic
parents.
In order to
decipher the natural history that resides in the DNA record, we have to have a
firm grasp of the language of DNA, and of how DNA information is decoded in
making the working parts of living organisms. Proteins are the molecules that
do all the work in every organism, from carrying oxygen, to building tissue, to
copying DNA for the next generation. DNA is made of two strands of four
distinct bases, represented by single letters A, C, G, and T. The strands of
DNA are held together by strong chemical bonds between pairs of bases that lie
on opposite sides, A pairs with C and G pairs with T. Amino acids are building
blocks of proteins, each amino acid is encoded as a combination of three bases
or a triplet in the DNA molecule. When assembled into chains of about 400, the
chemical properties of amino acids determine the unique activity of each
protein. Genes are the length of DNA that codes for an individual protein. In
human, and many other complex species, genes occupy only a small fraction of
the entire DNA, and are separated by long intervals of noncoding DNA. A lot of
this noncoding DNA is referred to as “junk”.
The
functions of immortal genes are central to fundamental, universal processes in
the cell, such as the decoding of DNA and RNA and the making of proteins. All
forms of life have depended upon these genes since the origin of complex
DNA-encoded life early in Earth’s history. These genes have survived through an
immense arc of time, and life will continue to depend upon this core set of
genes as it evolves in the future. Immortal genes have survived not because
they avoid mutation—they are as vulnerable to mutation as all other genes. The
genes are immortal in the sense that the gene as a unit endures; however, not
more detail inspection of their DNA sequences and of the sequences of the
proteins they encode, and it is a key demonstration of on aspect of the process
of natural selection.
In the DNA
record, there is more information than just the history of a particular
gene—there is information about the species that carries it, and about all of
the preceding species that also carried it, right back through eons of life’s
history. Due to the power of natural selection to preserve information that
would otherwise be erased in time, genomes contain a record of the history of
life. The new wealth of data from genomes offers unique insights into the deep
past that could not be deciphered from any other source.
Take Away Idea
From
chapter three the most important fact is that our DNA is made up of just four
bases, represented by letters A, C, G, and T. This was interesting because our
DNA hold the key to deciphering between all the different types of people on
the planet and when you break it down where all made up of the same four bases.
This fact also interest me because throughout history there have been many
conflicts in human history because of race but we all come from the same
chemical building blocks.
Most Challenging concept
The most challenging concept of the chapter is the thought
that we have almost identical protein sequence as tomato’s and yeast, but we
are completely different organisms. It’s hard to picture having some of the
same genetic make-up a tomato or yeast because humans are more complex organism
than they are. After reading this portion of the chapter, the question that
still sticks with me is, does having the same protein sequence as another
organism mean that you have the same genetic make up.
A Seminar Question
If we have
the same immortal genes as the archean division of life, what made us develop
into humans and the Archea stay the way they were?
Competency
In this
chapter of the novel, the aesthetic awareness competency was clearly portrayed.
First, the historical context of this novel comes into play when the author
discusses the relationship between eukaryotic ancestors from 2 billion years
ago and the members of the archean division. Next, the competency is displayed
through the author discussing the pink filaments that were around the
Also, the
critical thinking competency is demonstrated throughout the chapter. First, the
competency is shown in the beginning of the chapter, when the scientist noticed
pink filaments around a geyser and began experimenting to see if life could
exist in temperatures above 200 degrees F. Also the competency is displayed
when the author discuses how all three of the “superkindoms” were related.
Lastly, the competency is shown, when the author solves the problem of where
eukaryotes come from, which is a fusion between archea and bacteria.
Connection
Once I read this chapter the, the relationship between me
and my parents came to mind. Just like the eukaryotes came about from the
fusion of bacteria and archea, I came about from the fusion of my mother and
father. Also, the same way eukaryotes have different traits from the other two divisions;
I get my traits from my parents. Lastly, same way eukaryotes broke away from
the two other divisions and didn’t just stay single cell organisms; I’ll grow
up into someone different from my parents.
Vocabulary
Archea—third domain, or division of life
Eons--The longest division of geologic time, containing two
or more eras.
Leucine—a white, crystalline, water-soluble amino acid
obtained by the decomposition of proteins and made synthetically: essential in
the nutrition of humans and animals.
Key Concepts
1.
Eukaryotes came about
from fusion between archea and bacteria divisions.
2.
Immortal genes are
evidence of two key elements of the evelotionary process, the power of natural
selection to preserve the DNA record and the descent of life from common
ancestors.
3.
DNA is made of two
strands of four distinct bases, these building blocks are represented by the
single letters A, C, G, and T. The strands of DNA are held together by strong
chemical bonds between pairs of bases that lie on opposite strands—A always
pairs with T, C always pairs with G.