Genome Mutations: Why do they Happen?

Genome Editing (or Gene Editing) are the technologies that give scientists the ability to alter the DNA strands’ structure. These technologies are used to correct the genetic defects or to exclude the possibility of the serious diseases’ further transmission to the baby. They allow genetic material to be edited, or, in simple words, to be added, removed, or altered at the particular locations in the genome. Genome edition technology is the intervention with the unique options that can correct the known genetic defects.

1. DNA? DNA?? DNA??? What is ‘DNA’? Is there any basic info for the accurate DNA understanding? 

Your body contains from 5 billion to 200 million trillion tiny cells. The scientists cannot say the exact number because some types of the cells are easy to spot, while the others – such as tangled neurons that twist themselves up, or curl themselves up, or cuddle up to one another, making it impossible to count their number.

Virtually every tiny cell in your body contains the complete set of instructions for making you – you. These instructions are encrypted inside your DNA or the unique genetic code that makes you – you. Have you ever envisioned in your mind those tiny gorgeous DNA–curled spirals? DNA is a long, complex, ladder–shaped molecule that contains each person’s unique genetic code. And your unique genetic code is accurately designed, secretly encrypted, delicately enveloped and compactly packaged inside your DNA. 

As we have mentioned, DNA is a long, ladder–shaped molecule, designed especially to encrypt your unique genetic code. Each rung on the ladder is made up of a pair of interlocking units. These called interlocking units are called bases. They are designated by the four letters in the DNA alphabet – ‘A’, ‘T’, ‘G’ and ‘C’. ‘A’ always pairs with ‘T’, and ‘G’ always pairs with ‘C’.

2. DNA is so long molecule that it should be compactly packaged inside something and ‘ENVELOPED’

DNA molecules are too long. They are so long that they can’t fit into the cells without the accurate and compact packaging. To fit inside cells, DNA is curled up tightly to form the special thread–shaped structures – the chromosomes. And the chromosomes are the bundles of tightly coiled DNA located within the nucleus. In other words, the chromosomes are the gorgeous envelopes for the DNA molecules. Each chromosome contains a single DNA molecule. Metaphorically saying, the DNA molecule curls itself up, twists itself up, cuddles itself up, twirls itself up inside the chromosome.

Or scientifically saying, a single length of DNA is wrapped many times around lots of proteins, called ‘histones’, to form structures called nucleosomes. These nucleosomes then curl up tightly to create chromatin loops. The chromatin loops are then wrapped around each other to make a full chromosome. Each chromosome has two short arms (p arms), two longer arms (q arms), and a centromere holding it all together at the centre. Each of us has 23 pairs of chromosomes, which are found inside the cell’s nucleus. The DNA making up each of our chromosomes contains thousands of genes. At the ends of each of our chromosomes are sections of DNA called ‘telomeres’. Telomeres protect the ends of the chromosomes during DNA replication.

3. The most amusing fact about chromosomes: there are glittering chromosome tips at the ends of each chromosome (each chromosome tip has the sparkling molecular shoe on it. Isn’t it wonderful?)

Chromosomes do love the ought shoes couture. Therefore, there are so many glittering molecular shoes that are worn on every chromosome–tip. Sounds intriguing, isn’t it? These ‘shoes’ are called ‘telomeres’. Telomeres are the glittering chromosome–tips that prevent the gene loss. Every time a cell carries out DNA replication, the chromosomes are shortened by about 25–200 bases (‘A’, ‘C’, ‘G’, or ‘T’) per replication. However, ends of each of our chromosomes are protected by telomeres, the only part of the chromosome that is lost, is the telomere, and the DNA is left undamaged. Without telomeres, important DNA would be lost every time the cell divides. This would eventually lead to the loss of the entire gene.

4. Chromosomes are organized into Genes. Gene? Genes? What Are Genes? 

Chromosomes are further organized into short segments of DNA called genes. Genes are the essential templates the body uses to make the structural proteins and enzymes needed to build and maintain tissues and organs. They are made up of strands of genetic code, denoted by the letters ‘G’, ‘C’, ‘T’ and ‘A’.

Each of us has about 20,000 genes bundled into 23 pairs of chromosomes all curled up in the nucleus of nearly every cell in the body. It is interesting to note that only around 2% of our genetic code, or genome, is made up of genes. Another 10% regulates them, ensuring that genes turn on and off in the right cells at the right time, for instance. And the rest of our DNA is apparently a beautiful glittering accessory (as the DNA is long and ‘curly’ spiral molecule).

5. Genome. What is genome? Is that the same as ‘gene’ or something different? 

A genome is a body’s complete set of genetic instructions. Genome, or our unique genetic code, is made up of genes. Our genome is approximately 3,000,000,000 base pairs long and is packaged into 23 pairs of chromosomes. This set of instructions is known as our genome and is made up of DNA twisted–shaped molecules. DNA molecules have the encrypted unique chemical code that Manages everything in our bodies.

6. The Genome is multidimensional genetic code, but why it is also unique? 

Every genome is different because of mutations — ‘mistakes’ that occur occasionally in a DNA sequence. When a cell divides in two, it makes a copy of its genome, then parcels out one copy to each of the two new cells without verifying the copies of the genome. So, two cells have the valid but different genome copies. Theoretically, the entire genome sequence is copied exactly. But in practice, a wrong base is incorporated into the DNA sequence every time a cell divides in two, or a base or two might be left out or added. These mistakes or DNA pattern alterations are called ‘mutations’.

7. What types of gene mutations may occur?

Mutations may be natural or induced. They may occur at the chromosome level, gene level, or molecular level. Spontaneous mutations occur if the DNA application (DNA app fails to copy accurately) has some mistakes when a cell divides in two and makes a copy of its genome, then parcels out one copy to each of the two new cells without verifying the copies of the genome. So, two cells have the valid but different genome copies.

Induced mutations are caused by the artificial agents’ (mutagens) interventions.

1. Missense mutation (or Point mutation) is the most common type of gene mutation. This type of mutation changes a single nucleotide base pair. Point mutation is an alteration in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene. In other words, it is a change that occurs in a DNA sequence. Mutations are common in our DNA, but most of them have no detectable effect.
2. Substitution is the mutation when one or more bases in the sequence are replaced by the same number of bases (for example, a cytosine substituted for an adenine?
3. Inversion is the mutation when a segment of a chromosome is reversed end to end.
4. Insertion is the mutation when a base is added to the sequence.
5. Deletion is the mutation when a base is deleted from the sequence.

8. Why are the gene mutations dangerous?

A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors. Depending on where the mutations occur, they can affect the DNA sequence or even the chromosomes. They can have no effect on the DNA sequence and the chromosomes. Or they can change the DNA sequence or even the chromosomes so much that it would result in a genetic disorder.

Any type of mutation may cause the genetic disorder. A genetic disorder is a disease that is caused by a change, or mutation, in a person’s DNA sequence. The mutations can cause such diseases as Alzheimer’s disease, Cystic fibrosis, Hemophilia, Huntington’s disease, tumor diseases etc.

9. How to prevent or correct the genetic diseases?

The best way for prevention is testing. Genetic Testing is an incredibly useful tool for identifying changes or mutations in DNA that could lead to genetic disease.

Genetic Testing involves carrying out a range of tests on samples of DNA taken mainly from blood, hair, skin. The DNA sample is then sent to the laboratory where scientists look for specific changes in the DNA to find and identify any genetic disorders. The results of the Genetic Screening are then sent in writing to the doctor so that your doctor can discuss them with you. Your doctor can recommend you the alternative methods to solve your issues and to cope with your situation.

10. Genome Editing? What is genome editing? 

Genome editing is a technique used to precisely and efficiently modify DNA fragments within a cell. An enzyme cuts the DNA at a specific sequence, and when this is repaired by the cell a change or ‘edit’ is made to the sequence. Genome editing can be used to add, remove, or alter DNA in the genome. Genome editing is used to correct the genetic defects or to exclude the possibility of the serious diseases’ transmission to the baby.

CONCLUSIVE REMARKS: 

Genome editing is the introduction of changes in precise chromosomal DNA sequences. This technology not only changes DNA sequence specificity and double–stranded DNA but it presents the new opportunities for those suffering from serious genetic diseases. Literally, these technologies give those who has the genetic disease a chance.