Learning DNA in biology class is usually exciting but most students still find it difficult to understand. So in today’s Biology lesson, we will be looking at easy steps to proper understanding of the term DNA. As you learn, put down your questions, they will be attended to.
DNA (deoxyribonucleic acid) is a chemical substance present in the nucleus of every cell. It is passed from parents to offspring and is being regarded as a code of life. Since DNA is present in the nucleus and acidic in nature, it is also referred to as nucleic acid.
Structure of DNA
If you look closely at structure of DNA, you will observe that it is made up of two chains of small chemical units which are called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The nucleotides are twisted into each other to form a double-helix, something like a spiral staircase. The chemical structure of these bases are bond in certain pattern as adenine always joins thymine, and guanine always joins cytosine. In other words, the nitrogenous base (pyrimidine) of the opposite chain like rungs (steps) of a ladder. This is similar to the way the order of letters in the alphabet can be used to form a word, the order of nitrogen bases in a DNA sequence forms genes, which in the language of the cell, tells cells how to make proteins. Another type of nucleic acid, ribonucleic acid, or RNA, translates genetic information from DNA into proteins.
According to the U.S. National Library of Medicine (NLM), The order of these bases is what determines DNA’s instructions, or genetic code. Human DNA has around 3 billion bases, and more than 99 percent of those bases are the same in all people.
The structure of DNA
DNA molecules are long — so long, in fact, that they can’t fit into cells without the right packaging. To fit inside cells, DNA is coiled tightly to form structures we call chromosomes. Each chromosome contains a single DNA molecule. Humans have 23 pairs of chromosomes, which are found inside the cell’s nucleus.
DNA is as old as mankind but how it was discovered is something I myself could not figure out until I followed up a research where it was stated that DNA was first observed by a German biochemist named Frederich Miescher in 1869. But for many years, researchers did not realize the importance of this molecule. It was not until 1953 that James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin figured out the structure of DNA — a double helix — which they realized could carry biological information.
Watson, Crick and Wilkins were awarded the Nobel Prize in Medicine in 1962 “for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material.” Franklin was not included in the award, although her work was integral to the research. [Related: Unraveling the Human Genome: 6 Molecular Milestones]
DNA sequencing is technology that allows researchers to determine the order of bases in a DNA sequence. The technology can be used to determine the order of bases in genes, chromosomes, or an entire genome. In 2000, researchers completed the first full sequence of the human genome, according to a report by the National Human Genome Research Institute.
A person’s DNA contains information about their heritage, and can sometimes reveal whether they are at risk for certain diseases. DNA tests, or genetic tests, are used for a variety of reasons, including to diagnose genetic disorders, to determine whether a person is a carrier of a genetic mutation that they could pass on to their children, and to examine whether a person is at risk for a genetic disease. For instance, mutations in the BRCA1 and BRCA2 genes are known to increase the risk of breast and ovarian cancer, and analysis of these genes in a genetic test can reveal whether a person has these mutations.
Genetic test results can have implications for a person’s health, and the tests are often provided along with genetic counseling to help individuals understand the results and consequences of the test.
DNA Testing in Action
There are now many at-home genetic testing kits, but some of them are unreliable. Also, NBC News reports that people should be careful with these kits, since the tests are essentially handing over a person’s genetic code to a stranger.
New research on DNA
Now as a biology student, it is very important you know recent research that has been conducted on DNA. Some of these research are include:
DNA research has lead to some interesting, and important findings in the last few years. For example, a 2017 study published in the journal science found that random mistakes in DNA, not heredity or environmental factors, accounts for two -thirds of cancer mutations in cells.
According to findings from Another 2017 breakthrough is the first sequencing of DNA from Egyptian mummies. “We were excited to have at hand the first genome-wide data of ancient Egyptian Mummies,” said Stephan Schiffels, leader of the Population Genetics Group at the Max Planck Institute for the Science of Human History, in Jena, Germany. The findings were published in the May 2017 issue of the journal Nature communication.
Scientists sequenced DNA from mummies from the settlement of Abusir el-Meleq, south of Cairo, and were buried between 1380 B.C. and A.D. 425.
(Image: © bpk/Aegyptisches Museum und Papyrussammlung, SMB/Sandra Steiss
Movies were also encoded data to make a short video in the DNA molecules of bacteria in 2017. DNA was used as code for each pixel of the movie. The results were published in the July 2017 issue of Nature. “The point is not to store videos in bacteria,” said study co-author Seth Shipman, a postdoctoral fellow at Harvard Medical School in Boston. “We want to turn cells into historians,” Shipman said in a statement.
A still image from a movie that was stored in bacterial DNA. The image on the left is the original, and the image on the right is reconstructed from the data stored in DNA.
(Image: © National Institute of Mental Health
“We envision a biological memory system that’s much smaller and more versatile than today’s technologies, which will track many events nonintrusively over time.” For more details on this, see [How Scientists Stored a Movie Inside DNA] from livescience.
Importance of DNA
Disease Diagnosis and Treatment
One important area of DNA research is that of genetics and medical research. Due to our discovery of DNA, our ability to actually diagnose diseases early on has been vastly improved. In addition, we have been able to better assess a person’s genetic susceptibility to specific diseases. In doing so, we have also paved the pathway to formulate brand new drugs to treat these diseases. In fact, drugs can essentially be custom made to complement a person’s personal biochemistry and genetic makeup. For those diseases that were previously considered lethal and where treatment was either non-existent or largely unsuccessful, the discovery of DNA has essentially led to breakthrough drugs and treatments for patients with serious illnesses.
Paternity and Legal Impact
While the discovery of DNA has perhaps impacted medicine the most, its contribution to other areas is still similarly significant.
Paternity cases have an enormous impact on families and children around the world. Through the assessment of DNA, the paternity of a child can be identified, which has a significant effect on the child’s upbringing and his or her life.
Forensics and DNA
DNA has been notably important to the field of forensic science. The discovery of DNA has meant that the guilt or innocence of a person who is investigated for a crime can be determined. It also means that scarce evidence can still yield vital clues regarding the perpetrator of a crime.
Also important is that the identification of victims can occur, particularly in cases where the victim’s condition is unrecognisable to family or friends. In this sense, DNA has been important in revolutionising the entire field of forensic science. This impact is felt within the criminal justice system and contributes to the accurate safeguarding of society.
Agriculture and DNA
The impact of DNA on agriculture has been a very important one because it has allowed breeders to facilitate the breeding of animals that have a better resistance to diseases.
It also allows farmers to produce more nutritious produce, which has particularly important consequences in developing countries where the population subsists on a small range of staple foods that have little variety. This means that micronutrient deficiencies can be addressed in these countries.
DNA codes for all the cell proteins that make life possible. The cell transcribes DNA into RNA, which it then translates into proteins. These include the enzymes, hormones and structural proteins that each cell needs. Complex biochemical feedback loops determine which DNA genes are expressed. Through cellular biochemical pathways, genes control the shape of your nose and the size of your ears. If a gene is incorrectly coded, say due to a mutation in the DNA molecule, you may suffer from birth defects, such as a cleft palate, or genetic diseases including cystic fibrosis and Down’s syndrome.
DNA, the Code of Life
DNA is a complex, long-chained molecule that encodes the genetic characteristics of a living organism. In most plants and animals, DNA is packaged with ribonucleic acid and proteins into compact structures called chromosomes that reside in the cell nucleus. Almost all human cells have 23 pairs of chromosomes, one set from each parent. DNA sections called genes indirectly code for proteins, which give structure and function to human bodies. The choice of which genes operate in which cells determines the cell’s type: brain, liver, skin and all others.
In sexual reproduction, humans create special cells, called gametes, that contain but one set of 23 chromosomes. During fertilization, the father’s DNA unites with that of the mother to create a new, unique set of 46 chromosomes.
This is how an ancestor’s traits are passed down to offspring. One particular chromosome in a gamete determines the gender of offspring. That chromosome can be the X or the Y: two X’s create a female, while XY produces a male. As the fertilized egg begins to divide, different genes control how cells differentiate from each other, creating the various human tissues, organs and systems.
Life and Death
DNA is essential for the life of the human cell, yet it can fragment, leading to cell death. Science has not fully unraveled this mystery — scientists do not know whether DNA is programmed to self-destruct. Thirty-seven genes of nonchromosomal DNA reside in human mitochondria, the cell’s power plants. This DNA codes for important RNA molecules, some of which produce enzymes required for metabolism. Mutations of mitochondrial DNA can cause newborns to die. Not all mutations are bad — evolution is essentially a long story of beneficial DNA mutations that have transformed the simplest one-cell organism into higher forms of life, including human beings.
DNA Importance Continues
While the discovery of DNA has been a significant one in the twentieth century, it will continue to revolutionise medicine, agriculture, forensics, paternity and many other important fields in society today. DNA research encompasses an evolving area of progress and continued funding and interest in its relevance will likely fuel new discoveries in the future.
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