You are probably familiar with the fact your DNA is the molecule that codes for the traits that make you unique. Except for identical twins, there are no two individuals that have the same sequence of DNA. However, you may not be as familiar with the concept of mutations, which cause permanent changes to the DNA sequence in our cells. We will explore the types of factors that cause mutations and the impacts of those mutations on individuals. Mutagens, or mutation-causing agents, come in three forms: physical, chemical, and biological. Let’s first explore the physical mutagens, most commonly from high energy radiation. Ultraviolet radiation and X-rays are higher energy waves that can damage DNA. Most UV exposure comes from being outside during daylight hours. Harmful UV rays can cause two adjacent thymine bases in the DNA to dimerize, or bond with each other, as opposed to to pairing with adenine across the molecule. This can lead to incorrect DNA replication and incorrect base pairing. If this change is permanent, then a mutation has occurred. X-rays also cause DNA damage, resulting in potentially permanent mutations. The good news is that exposure to both UV and X-rays can be minimized through personal behavior like wearing appropriate clothing or sunscreen when outside during daylight hours. Chemical mutagenic factors include the numerous compounds found in cigarettes, like the aromatic hydrocarbon benzene. Some of these same or similar chemicals can be found as food preservatives, and have been linked to DNA mutations that lead to cancer. Some compounds in industrial cleaners and some cosmetics have also been linked to higher incidence of mutations. One mode of action that causes the mutation is the change of an amine group of an adenine base to a ketone group. This can lead to a mismatch of base pairs in the DNA. Again, if this change is permanent, a mutation has occurred. There are also biological agents that can alter the DNA of infected cells. Viruses are packages of nucleic acids that can hijack host cells in order to replicate their genomes. During a viral infection, the DNA of the host cell can be altered. This alteration, if permanent, can be considered a mutation. Human papillomavirus, HPV, is commonly linked to cervical cancer due to the changes it makes to the infected cells. With so many different potential mutagenic factors out there, there are bound to be DNA changes in every individual. The outcomes of DNA changes can be varied. Some mutations are repaired and are not permanent. Other mutations are permanent changes to the DNA, but the same amino acid is still coded for in its place. This is known as a silent mutation because the structure and function of the protein will be maintained. Other mutations can result in a STOP codon being encountered prematurely or a different amino acid being coded for. These cause significant changes to the protein structure and function. This can be harmful if the phenotype change to the individual makes them a poorer fit in their environment. As mentioned earlier, many of the mutagenic factors are also considered to be carcinogens, as they can increase the likelihood of cancer. The good news is that avoiding mutagens is possible. Knowing the main sources of these DNA-changing factors allows us to be aware so that we can minimize our exposure to them and their impacts on us.
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Question 1
A change in the DNA sequence by adding, deleting, or rearranging one or more nitrogen bases is called a _________.
Responses
A mutationmutation
B segregationsegregation
Question 2
One of the most common mutagens in our environment, that we are exposed to everyday we are outside in the sunlight, is ________.
Responses
A UV radiationUV radiation
B infrared radiationinfrared radiation
Question 3
Mutations can cause cells to divide repeatedly and this can eventually cause __________.
Responses
A genotypegenotype
B cancer
cancer
please answer all 3 questions
Question 1:
A change in the DNA sequence by adding, deleting, or rearranging one or more nitrogen bases is called a mutation.
Question 2:
One of the most common mutagens in our environment, that we are exposed to every day we are outside in the sunlight, is UV radiation.
Question 3:
Mutations can cause cells to divide repeatedly and this can eventually cause cancer.