THE FUNCTION OF DNA
AND GENETIC
ENGINEERING
By: Liam Grinton
Due: October 30th.
INTRODUCTION:
For this investigation, I had a set of questions that I had created as my goal, or a set of
guidelines. By the end of my investigation and the end of my research I wanted to have these
questions answered to the best of my ability, and understand the topics fully. I had one main,
over- arching question, however beneath those were several, more specific ones to narrow down
my areas of research. Below are the questions that I intended to answer.
What is the function of DNA and genetic engineering? My sub- questions are as follow:
How do cells make copies? What is mutation? What is DNA? What is Genetic engineering?
These questions are relatively broad and unspecific; therefore it will only be productive to study
them within a certain context. The context that I wished to explore is that of their future uses,
and scientific development and study.
DNA is an abbreviation for deoxyribonucleic acid, and is a biochemical term for a linear
polymer found in the nuclei of cells. DNA is formed of nucleotides and is shaped like a double
helix; it is a key component in the transmission and storage of genetic information. Genetic
engineering is the deliberate modification of an organism’s genetic structure.
I have found it helpful, and will therefore explain DNA in comparison to a computer
program, using binary code.
I will break down the topic, into its individual parts in order to study them separately, and
I will write the essay by breaking the results of my work into the appropriate sections.
BODY:
DNA:
DNA is a term used to describe Deoxyribonucleic acid. DNA is a long linear molecule
formed of nucleotides that is found in the nucleus of a cell. DNA has a crucial role in that it is the
molecular structure that houses the hereditary information of the cell and all of the other cells
needed to produce an organism. Most DNA is found in the cell’s
Fig. 1.1
nucleus, however some DNA can be found in the mitochondria of
the cell, where it is called mitochondrial DNA or mtDNA.
Computer programs use what is called binary code. Binary code is
a series of zeroes and ones that are arranged in a specific pattern
to form a legible number “sentence” to transmit or store
information. DNA is similar to binary code in that it stores
information on the basis of four different chemicals called bases.
A DNA strand, illustrating the
four different bases of DNA
Binary code has two bases, zero and one. The chemical bases of DNA are adenine (A), cytosine
(C), thymine (T), and guanine (G) as illustrated in fig. 1.1. The human DNA sequence has about
3billion bases, and 99 percent of those are the same in all people. As illustrated in fig. 1.1, DNA
bases pair up with each other; these paired units are called base pairs. The bases also bond with a
phosphate and a sugar4 molecule to form a nucleotide. The nucleotides arrange in long strands,
in their specific order to form what is referred to as the double helix. An important property of
the DNA molecule is that it can replicate. This is necessary because when cells divide in cell
division, it is crucial that the new cell have an exact copy of the original’s DNA. Each strand in
the double helix acts as a pattern or template for creating a duplicate of the base sequence. [1]
Recombinant DNA:
Recombinant DNA is A DNA sequence produced artificially by joining pieces of DNA
from different organisms. [3]
Chromosomes:
In the nucleus of a cell, the DNA molecule isn’t just floating around randomly, it is
packaged, tightly wrapped, into structures called chromosomes. A
Fig. 1.2
chromosome consists of the DNA molecule coiled many times around a
protein substrate called a histone. The chromosome is not visible- even
under a microscope. Only when the cell is about to divide does it
become tightly packed and visible under a microscope. Each
chromosome has a point called the constriction point, or centromere.
This point divides the chromosome into two arms labeled the “p arm”
and the “q arm” these arms aid in the locating of specific genes. [4]
GENETIC ENGINEERING:
This image shows the composition and
shape of a chromosome.
Genetic engineering is the use of rDNA or recombinant DNA, to introduce desirable
traits into an organism. This is called rDNA technology. Scientists are able to remove segnents
of the DNA molecule from an organism; this segment is then spliced into the DNA molecule of
another organism to influence its traits. A similar process has been used for hundreds of years to
enhance the traits of animals by selective breeding, breeding animals with desirable traits
together repetitively over time; however, rDNA technology is much faster, more targeted at
specific traits, and overall, much more powerful.[5] This technology has many benefits and many
downsides- “with great power comes great responsibility”.
Hybridization:
Hybridization is a field of genetics in which different species or varieties of animals or
plants are crossbred, mixed, or altered to create a hybrid. The hybridization of plants usually
takes place by taking pollen from one plant’s stamen and brushing it onto another plant’s stigma.
Only similar plants can be crossed with a high rate of success in creating an offspring with the
desired traits, although some great gaps have been crossed with success.
HOW CELLS MAKE COPIES:
All cells must create a copy of their DNA before cell division. This is crucial because all
of the hereditary information that allows the cell to survive and
Fig. 1.3
reproduce must be transferred to the new cell. Because all organisms
have from thousands, to several billion bases in their DNA molecule,
this is a rather daunting task. Cells use enzymes to reproduce their
DNA molecule, a relatively simple means to complete such a complex
task. Some enzymes unwind the double helix, others separate the two
A cell in the process of cell
division
strands, and others construct other strands that are complementary to the original ones. After the
DNA is replicated, another set of enzymes checks the work of the others, removing and fixing
mistakes. The resulting two exact copies of the DNA/ chromosome are finished. One of the
copies can then be partitioned to the “sister cell” during cell division. [8]
MITOSIS/ MEIOSIS:
Mitosis is the process in which the equal partitioning of the newly replicated
chromosomes into identical groups takes place. Before this process can occur, the chromosomes
need to become aligned so that the process can happen in an orderly fashion. This alignment of
the chromosomes and the partitioning into groups is a process that can be seen in almost all
eukaryotic cells. [9] Meiosis is different; during the division process, there are two divisions, so in
the end the product is four cells as opposed to two cells with mitosis. After the division process
has ended in meiosis, each of the product cells has only half the number of chromosomes that the
original cell had. These end cells that only have half the number of chromosomes, are called
haploid cells, or gamete cells. The purpose of these cells will eventually be to find other haploid
cells to combine with to form a new organism. [10]
MUTATION:
A mutation is a change in the DNA sequence of a gene. Mutations in the sequence of the
DNA molecule can alter amino acid sequences and the proteins encoded by that gene. This can
happen because, like words in a sentence, the DNA sequence of each individual gene decides an
amino acid sequence of the protein it is responsible for encoding. The DNA sequence is
interpreted into codons, groups of three nucleotide bases each. The DNA sequence of a gene can
be thought of as a sentence made entirely of three letter words like the one below: each three
letter word is a codon that specifies an amino acid in a protein.
Thebaddogwasbadanddidnotgettheoldmanhishat.
If you were to split the sentence up into its individual codons it would read:
The bad dog was bad and did not get the old man his hat.
Each letter represents a nucleotide base, and each letter a codon, if you were to change the
“reading frame” the sentence would read differently:
T heb add ogw asb ada ndd idn otg ett heo ldm anh ish at.
Only one of the possible reading frames makes a legible, sensible, sentence; in the same way,
you can mutate the reading frame of a gene, and create a sentence that does not read what it
should. Occasionally a mutation will come along that does not only read nonsense but reads
something legible but different than originally intended, this is also genetic mutation. [11]
CANCER:
Cancer is a disease that is classified by out- of – control cell growth. In a normal human
body cells are formed, grow, divide, and die on a repetitive and controlled time schedule. Old
cells die and are replaced by new ones. When a cell’s DNA tells it to die, it is called apoptosis.
There are over 100 types of cancer, all classified by the original cells affected. Cancer harms the
body when out- of- control cells whose genetic information had been damaged or mutated, grow
out of control and no longer die due to apoptosis. The only exception to this is leukemia where
cancer changes normal blood function because of abnormal cell division of the cells in the blood
stream. Tumors are dangerous because they can interfere with the function of the body’s organ
systems, circulatory systems, and nervous systems. Tumors can also excrete hormones that alter
bodily function. Benign tumors are those that show little growth and stay in one spot.
More dangerous tumors, called malignant tumors, form when two things occur.
Cancerous cells are able to move through the body and destroy healthy cells in a process called
innovation. They then form new tumors in other places, this is called metastasis. When a tumor
is able to divide and grow, creating new blood vessels to feed itself, this is called angiogenesis.
[12]
CONCLUSION:
My goal was to answer my initial questions about the function of DNA and genetic
Engineering, and my sub questions concerning mutation, DNA, Genetic Engineering, and how
cells make copies, and display the information in a legible and comprehensible manner.
DNA stands for Deoxyribonucleic acid and is a long linear polymer consisting of
nucleotide bases that stores and transfers genetic information. Genetic Engineering is a process,
using rDNA technology to take desirable traits, in the form of genetic information and splice it
into another organism to carry on those traits. Cells make copies of themselves to reproduce,
they must copy their genetic information and transfer a copy to the new cell before cell division
may commence. There are two main types of cellular reproduction, mitosis, and meiosis.
Mutation is when the genetic information of a cell becomes altered or damaged, this may create
an abnormal cell, group of cells, or organism.
The future uses of DNA and genetic engineering are numerous; there could be many
benefits and many hazards. Genetic engineering and the knowledge and study of DNA could
make organisms more useful or resilient to their environment; crops grow with less water, and be
more resistant to pests. We always must be mindful that every alteration that we make may have
consequences and be dangerous; it will be all too easy to upset nature’s balance. If we are not
cautious we will have the benefits along with the hazards and disadvantages, if we are cautious,
we can reap the benefits without the consequences. Either way, science has the capability of
making great changes to the way we live on this earth.
WORKS CITED
1. ^ http://ghr.nlm.nih.gov/handbook/basics?show=all#dna
2. ^ [fig. 1.1] U.S. national Library of Medicine
3. ^www.accessexcellence.org/RC/AB/WYW/wkbooks/SFTS/glossary.php\
4. ^ http://ghr.nlm.nih.gov/handbook/basics/chromosome
5 ^
http://www.fda.gov/AnimalVeterinary/DevelopmentApprovalProcess/GeneticEngineering/G
eneticallyEngineeredAnimals/ucm113597.htm
6 ^ [fig.1.2] U.S. Library of Medicine
7 ^ [fig.1.3]
http://protist.i.hosei.ac.jp/PDB/images/Sarcodina/Heliozoa/Actinosphaerium/cell_division_1.
jpg
8 ^ http://www.sci.uidaho.edu/bionet/biol115/t6_cell_growth/lesson2.htm
9 ^ http://www.life.umd.edu/cbmg/faculty/wolniak/wolniakmitosis.html
10 ^ ^ http://www.biology4kids.com/files/cell2_meiosis.html
11 ^ http://learn.genetics.utah.edu/archive/mutations/index.html
12 ^ http://www.medicalnewstoday.com/info/cancer-oncology/