Cancer and DNA

With hundreds of thousands of Britons receiving a cancer diagnosis each year and millions around the world being diagnosed, the aim to successfully treat cancer is an important one for researchers. Our knowledge of cancer thus far has shown it to be a complex disease that involves numerous factors such as genetics, lifestyle and environmental factors. The area of genetics is a particularly vital one because it is suggested that our genes are the starting point for disease susceptibility and in some cases, genetics are the determining factor while in other cases, this predisposition to cancer can be triggered by lifestyle and the environment.

DNA Damage and Cancer

DNA damage is not an unusual or isolated event. Rather, we all suffer from DNA damage within cells during our lives. When DNA is copied, many mistakes can and do occur - the process is not a perfectly efficient one. As such, mistakes will occur and these may be rapidly repaired by DNA repair systems or they may accumulate, particularly due to ageing or if the body is repeatedly exposed to a harmful stimulus over time. Add to this the fact that by-products from normal metabolism and other required reactions in our bodies may trigger damage to DNA, and you can see how damage to our DNA can actually occur quite easily.

If you think about other aspects of life, such as your environment, consider things like smoke, radiation from the sun and other toxins. All of these parts of our day-to-day environment can cause repeated damage to DNA in cells. The consequences can mean a constant barrage of damage throughout the day, all of which each of your cells must withstand. Yet, not everyone ends up developing cancer, so clearly the combination of the body's repair systems, biochemistry, familial history, lifestyle and likely many still unknown factors come together to protect the body from cancer. In most cases as well, a cell can repair damage to DNA quite well and the body has some resilience to mistakes in DNA copying. In fact, even major DNA damage can be addressed through signals for cell apoptosis, which is the way a cell is programmed to die where appropriate.

When DNA Repair is Unsuccessful

Even with your body's systems of repair and resilience to damage, the body can still become overwhelmed with damage and cancer can occur. Also perhaps surprising is that cancer can be caused by malfunctions and mutations in the genes that govern the cell repair itself. This means that mutations may initially occur, followed by mutations in the mechanisms for repairing these initial problems. Thus far, genes have fortunately been identified with regards to mutations linked to cancer.

You may have even heard the terms already in the media. The first are tumour suppressor genes, which work to fix DNA errors, direct apoptosis and also affect the rate of cell division. If damaged, tumour suppressor genes can lead to cancer. The second are oncogenes, which are mutated forms of normal genes known as proto-oncogenes. Oncogenes carry DNA sequences known to lead to cancer. There are, of course, other genes that can mutate and may also improve a cancer's ability to persevere in a person's body. Such genes may facilitate 'better' delivery of the cancer to other areas of the body or may work to shield injured cells from apoptosis.

Differences between DNA and RNA

DNA and RNA are two molecules that are found in the cells of every organism. DNA stands for Deoxyribonucleic acid while RNA is short for Ribonucleic acid. Both have specific functions related to the growth and replication of the organism through cell division and protein synthesis. However, DNA and RNA have differences in both structure and use.

The main difference between DNA and RNA molecules is the type of sugar that is present in them. DNA is composed of deoxyribose sugar while RNA is made up of ribose sugar. The main difference between the two sugars is that deoxyribose has more OH.

Another difference between DNA and RNA is their predominant structure. DNA is a double-stranded molecule with a long chain of nucleotides while RNA is a single-stranded molecule having shorter chains of nucleotides. Both DNA and RNA are polymers however; each molecule has its own set of bases. The difference in DNA and RNA bases is that RNA has the base uracil, and DNA has a base of thymine.

The difference in roles each of these molecules has in cell biology is: DNA serves as the storage of genetic information of an organism, while RNA acts as a messenger that relays the genetic information from the nucleus to the ribosome.

DNA and RNA

DNA

DNA, short for Deoxyribose nucleic acid, is the chemical that is found inside the nucleus of the cells of all organisms. It carries the vital genetic codes that dictate how an organism will grow and shape. Each DNA molecule consists of two long strands that are wrapped around each other. Because of this, the DNA structure resembles a double spiral "staircase" or a helix. An actual microscope photo of a DNA stand is shown in the below figure:

Each rung of the DNA ladder is composed of two substances, known as bases, which lock together. All in all, there are four different types of bases, and together they create four different kinds of rungs. The exact DNA sequencing of these rungs makes up a cell’s chemical information. This DNA information is vital since it shapes the cell’s development and regulates every single detail of how a cell should work. DNA contains chemical information known as genes. These genes are individual instructions in the code that tells the body’s cells how to produce new proteins.

DNA replicates before cell division so that a full set of DNA information is given to each new cell. During cell division, DNA molecules tighten up to form chromosomes. These chromosomes undergo a series of events and eventually replicate so that each new cell will have the same genetic information found in the originals, and the newly-formed cells will function the same way as those of the parent cells.

RNA
In order to better understand what Ribonucleic Acid (RNA) is, it is first important to know what is happening inside an organism’s cell.

Inside every living cell, the actual process of creating new proteins undergoes several different steps and the instructions for these steps are contained in the nucleus of the cells. However, the proteins themselves are synthesized outside the nucleus, in an area known as the cytoplasm. This means that the cells must have a way to relay the information contained in the nucleus towards the cytoplasm. As it turns out, cells utilize a special molecule known as the messenger RNA to transcribe the genetic code found inside the nucleus.

RNA is very similar to DNA, Deoxyribonucleic acid, which contains the vital genetic information of the cell. RNA, when compared to DNA, has only a single strand and has a ribose sugar instead of the deoxyribose sugar. Furthermore, the base of the RNA is Uracil instead of Thymine which is found in DNA. RNA is produced by the RNA polymerase enzyme. This enzyme is responsible for RNA synthesis.

Whenever new proteins are needed by the cell, it sends a chemical signal to the nucleus which causes a gene for that protein to be 'switched on'. When this happens, the DNA codes are copied to the messenger RNA in the process known as genetic transcription. After the codes have been copied, the messenger RNA carries the information to the ribosome which is responsible for the protein synthesis. The messenger RNA then releases the codes to the transfer RNA which eventually translates the codes in the right order inside the ribosome.

Once the code is being translated in the ribosome and the required protein is synthesized, a mechanism known as RNA interference takes place, turning off the gene so it doesn't send more messenger RNA to the ribosome.

DNA and RNA

DNA and RNA are two different nucleic acids found in the cells of every living organism. Both have significant roles to play in cell biology. DNA and RNA structure are similar because they both consist of long chains of nucleotide units. However, there are a few structural details that distinguish them from each other, and if you are to compare DNA and RNA, these would be the results:

(1) RNA is single-stranded while DNA is a double-stranded helix.

(2) RNA also has uracil as its base while the DNA base is thymine. However, even with the differences in their structures, DNA and RNA have cooperating roles in the field of Cell Biology.

DNA contains the genetic information of an organism, and this information dictates how the body’s cells would construct new proteins according to the genetic code of the organism. Within the cell structure, DNA is organized into structures called chromosomes, which are duplicated during cell division.

These chromosomes would then release the genetic codes that will be transcribed and carried by the RNA (specifically the messenger RNA) to the ribosome. The ribosome will then synthesize new proteins that will help the body grow. This is the how the DNA and RNA work together in the body.