My Final Human Biology Paper
Whenever
something happens to my family and I characteristically-wise, we always make
references to “it’s because you’ve inherited my genes.” I’ve inherited some certain genes from my Dad
and others from my Mom, and I’ve always wondered how I was able to acquire
these traits. Taking a psychology class
some time ago only made me wanted to explore the subject even more. My goal for this paper is to try to
understand how the DNA inside our bodies work, how they relate to our genes,
and most importantly, how it relates to biology.
First off, what is DNA? DNA stands for deoxyribonucleic acid and is a
double-helix structure within our bodies, and it holds all our genetic
information. It transmits that genetic
information to make other cells and even new organisms. The structure is made out of nucleotides, and
each of these nucleotides is made up of four types of nitrogen bases, which are
adenine, thymine, guanine, and cytosine.
Depending on the order of these nitrogen bases, we can tell that each
nucleotide holds a certain genetic code that we can inherit in our bodies. The nucleotides are attached to each other
throughout the entire helix, meaning each strand contains a gene we inherit.
Now just how long is the DNA? Well, they are so long that they can’t fit in
any of the cells unless they are packaged right. In order to make them fit, DNA is coiled
tightly so that they form structures called chromosomes. Each chromosome contains a single DNA
molecule, and are found inside the cell’s nucleus. Human beings have 23 pairs of chromosomes in
every cell.
It’s unclear to us on just how long
DNA has been around. In the 4 billion
years of life on Earth, it’s a possibility that DNA allowed all living things
to function, grow, and reproduce just like today. However, it had been proposed that the
earliest forms of life had used RNA as their genetic material. RNA stands for ribonucleic acid, and they are
expressed as coding, decoding, regulation, and expression of the genes. The difference between DNA and RNA is that
the DNA is like a blueprint of guidelines that an organism must have to exist
and function, while the RNA carries out those guidelines.
Going back to the history of RNA, it
is possible that the RNA acted as the central part of early cell metabolism as
it can both transmit genetic information and carry out catalysis as part of
ribozymes. These may have influenced the
evolution of the current genetic code based on the four nucleotide bases. However, it’s not clear that there is
evidence of ancient genetic systems, as recovery of DNA from most fossils is
impossible because DNA survives in the environment for less than one million
years, and slowly degrades into short fragments in solution.
There is also the solution that our
building blocks of DNA, that is, the nitrogen bases, were actually formed in
outer space. DNA and RNA organic
compounds of life, like uracil, cytosine, and thymine, have also been formed in
the laboratory under conditions similar to those found in outer space, using
chemicals found in meteorites. These are
only theories though, as there is no clear evidence of how DNA actually
started.
When it comes to us personally
though, we receive our DNA from our parents, grandparents, great-grandparents,
and so forth. DNA is actually passed
down from the parent to the child using half their chromosomes. If nothing happened to the chromosomes
between generations, then there would be around a 1 in 8 chance that you would
get no DNA from your great, great, great grandparent. Chromosomes can get mixed and match before
they are passed on.
One of each pair of our chromosomes
comes from our parents, which is why we are 50% related to our mothers, and 50%
related to our fathers. If that’s the
case, then the chromosomes our parents got from their parents are also passed
on to us, making our inheritance to our grandparents about 25% each. This is the beauty of recombination, which is
the rearrangement of genetic material, that is, crossing over in chromosomes
from different organisms. Suffice to say,
all living organisms do this.
Now what kind of traits and
inheritance do we actually get from these chromosomes into our DNA? Going back to how I started, I would get sick
easily whenever my family drives through the mountains. This happens to my mother, as well as her
dad. This is an example of gene
heritage, because I inherited this particular trait from my mother. But DNA is much more than that. They could express certain body traits that
we have, such as eye color, body shapes, and even our behaviors. There are some researchers that actually
believe that genes influence stuff like alcoholism, homosexuality, and a
predisposition of anxiety.
Now, is whatever we have and do in
life all inherited from our ancestors?
Actually, no. There is another
process in DNA called mutation. Mutation
is a change in DNA, or the hereditary material of life. Whatever genes we inherited from our parents,
could be changed through mutation. You
could say that your DNA retrieves a huge influence from the world through
activities and substances, and that could undergo this mutation, and change the
way you live.
Mutation is a very important aspect
in evolution, because they are the raw material of genetic variation. Simply put, without mutation, evolution could
not occur, and we would not be depicted as unique from one person to the
other. There are other types of
mutation, such as insertion, which extra base pairs of nitrogen are inserted
into a new place in the DNA. Another
includes deletion, in which a section of DNA gets lost, or deleted. And the most complicated change in DNA is
frameshift.
Since DNA is divided into codons
three bases long, insertions and deletions can alter a gene so that its message
is no longer correctly parsed. This is
frameshift. A good example of this would
be comparing it to this sentence: “The fat cat sat.” Each word represents a codon. Thanks to mutation, if we delete the first
letter and parse the sentence in the same way, it wouldn’t make sense at
all. Now it just reads: “Hef atc ats
at.” Mutation makes that much of a
difference.
Overall, DNA has had a massive
influence in biology and our daily lives.
When it comes to studying different organisms, DNA is the sole center
reason of how they act and what they look like.
DNA also helps control our proteins, in fact, without proteins, the DNA
cannot function properly. These
interactions with proteins can be non-specific, or rather, the protein can bind
specifically to a single DNA sequence. Enzymes
can also bind to DNA and of these, the polymerases that copy the DNA base
sequence in transcription and DNA replication are very important to DNA
functionality.
These are my studies on the
structure, origins, and the works of the DNA.
Without DNA, we will not be able to be unique from one another. We do not know where it originates from, but
we do know that we inherit our genes from our parents and ancestors. This ultimately defines us on who we are.
References
1. Understanding DNA: The molecule and How It Works Third Edition
3. http://www.nature.com/scitable/topicpage/chromosomes-14121320
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