Stephanie Miller—Sec: 001
Mai Nguyen—Sec: 001
Devon Harvey—Sec: 003
Biology Writing Assignment #3
The central dogma of biology is summarized as DNA – RNA – Proteins. When this was
first discovered, it revolutionized everything we know and understand about biology. In order for
scientists to come to this conclusion, they had to accept that DNA was the genetic material and not
the proteins. When this was established and the central dogma was accepted, many new
experiments were conducted regarding genes and DNA. Some of the many fields scientists focused
on were: where new alleles in society originated from and how those new alleles affect the
phenotypes of mankind.
To understand where new alleles come from, scientists started researching genes within the
DNA of different organisms and found that there were inconsistencies among the species. This led
to the concept of mutations. This is where sequences of DNA nucleotides are deleted, substituted,
and/or inserted. Mutations can occur due to environmental factors or mistakes made to proteins
during DNA replication. There are two types of mutations: point and frameshift.
Point mutations can be further classified into three categories. They are silent, missense,
and nonsense. A silent mutation is when DNA is being transcripted into MRNA, a single
nucleotide is substituted. However, there is no effect because the codon that contains the
nucleotide still yields the same amino acid; the same protein. Missense is known as the substitution
of a nucleotide that eventually codes for a different amino acid. This means that the protein will be
slightly altered, resulting in a reformed function. The final point mutation, nonsense, is similar to
missense in that a nucleotide gets replaced, but the outcome of nonsense is a stop codon. The
other type of mutation, known as frameshift, is the insertion or deletion of nucleotides which
results in a completely new protein.
Stephanie Miller—Sec: 001
Mai Nguyen—Sec: 001
Devon Harvey—Sec: 003
The next step in learning about this new information is how these mutations affect alleles
that will potentially be passed on to offspring and begin a new characteristic among the population.
An allele is an area on a chromosome that codes for a trait. When looking a genotype or
phenotype, you are looking at which alleles are being expressed. Genotype is looking at the
genetics and phenotype is the physical appearance. If the DNA has been mutated then it could
result in a new allele leading to a new genotype and phenotype. This is very important in evolution
because it explains how species look, act, and respond differently in various environments.
These studies prove that DNA is the genetic material. Mutations in the DNA sequences
affect which proteins are made therefore creating different functions in cells. Also, mutations can
cause new alleles to form in chromosomes that can potentially be passed on in further generations.
Using this information, there is potential to force mutations thus causing new functions and alleles
to form. With new alleles come new genotypes and phenotypes that may be able to strengthen the
progression of the human race.