Genetics has great importance in our lives. It is a branch of medical science. We become amazed after seeing the phenomenons occurring in Genetics. It compels us to think that how wonderfully traits transmit from one generation to another. Genetics has given us a lot of benefits in different biological fields of life, these fields include Agriculture, Medicine, Forensics, Aquaculture and Ecology. Genetic engineering is the great gift of Genetics.A big revolution has come especially in the field of Medicine due to Genetics. It is because of Genetics that today we know the reasons of many diseases. It has made the life of patients easier as compared to the past. Along with the good effects there are also bad effects of Genetics which can not be neglected. Genetic discrimination, ethical issues, effects on the environment, public health, genetic privacy and confidentiality are of more significance among all the harmful effects of Genetics. There are so many things in the subject of Genetics, which we do not know, and which are needed to be discover, for example, we do not know the function of a huge part of our genome.
Genetics is the study of heridity. We study the pattern of transmission of characteristics ( like eye colour, skin color, ear lobe, height, blood group, our likes and dislikes, our way of thinking and talking etc ) from parents to offsprings. Traits transfer in the form of genes which are also called heriditery units. The word ”Genetics” has meaning of genesis (origin). DNA has same place in Genetics as the place of water in life. Gregor Mendal is called the father of Genetics. He performed the experiments on pea plant. The traits studied by Mendal are monogenic ( traits affected by single gene ) but today we know that polygenic traits (traits affected by more then one gene ) also exist. Genes consist of nucleotide ( suger + nitrogenous base; adenine, guanine, cytosine, thymine + phosphate group ) sequences. Our genetic information is stored in the form of genetic codes. Three nucleotides make one genetic code or codon. One codon encodes for single amino acid. These amino acids make long polypeptide chains then protein formation occur. Proteins have great significance in our body, even without proteins biochemical reactions can not occur. Gene regulators, enzymes, harmones, antibodies all are examples of different types of proteins. Same nucleotide arrangement is present in all the cells present in our body. All the information of functions being performed in our body is stored in our genome. All the human beings have similar nucleotide sequence but the difference is very very small, this is the reason that no human being is present on the earth having same physical features with other human beings.
DNA – heriditery material
In modern Genetics we study function and performance of different genes along with inheritance pattern. A human body has 46 chromosomes, out of which 23 come from mother and 23 come from father. There are 8,388,608 possible combinations of egg and sperm. Chromosomes are thread like structures consist of DNA. We classify chromosomes on the basis of size, centromeric position, affinity for staining dyes and number of bands present on p ( short ) and q ( long ) arms. There are 22 pairs of autosomes and 1 pair of sex chromosome. Mutation ( change in DNA structure ) in autosomes do not affect next generation but mutation in sex chromosomes ( X,Y ) transmit in next generation. There are 20,000 genes on 23 pairs of chromosomes. There are 8,388,608 possible combinations of egg and sperm.
Benefits of Genetics:
These are the following fields of life sciences which have got the benefits due to Genetiics.
Genetics has the unique position in the field of Agriculture. The level of progress in Agriculture has been increased due to advancements in the field of Genetics. We insert our gene of interest ( herbicides or disease resistance gene ) in the plant genome. The plant lacking that gene become susceptible to that disease or herbicides. Thus that plant becomes genetically modified ( plant having foreign gene in its genome ). Plants yield is also increased by inserting our desired gene. We use method of selective breeding, cross two plants with good features to get the plant with our desired characteristics.
Genetically modified Plants
Similarly, yield of plants can be increased by inserting the desired gene in plant genome. Efficiency of Rubisco can also be increased. We change the structure of stomata in such a way that it can take in and take out gases easily. Genetically modified plant can produce antibodies and harmones in large amount. Transgenic plants can survive in the environment having high salt, low water content and presence of aluminum. We can get seedless fruits and lean meat. Golden rice have been produced by inserting transgenes of corn and bacteria into rice.
Golden rice have superiority over simple rice that it has more vitamin A content. The use of pesticides has been reduced. The nitrogen fixation is better and post harvest losses are reduced . Bacillus thuringiensis has gene toxic to insects when it is inserted in the corn , corn becomes resistant to insects attack. Ethanol, acetone and methane can be produced by the activity of transgenic microorganisms on the agricultural and industrial waste.
Genetically modified microbes
Renin ( cheese producing enzyme ) was obtained from stomach of calves but today we insert its gene in micoorganism and gain renin in large amount. Bacteria can act as biofilters, they catch the sulfur produced by the burning of coal then die after their work because we insert suicide gene in them to protect the environment.
First genetically engineered product was human insulin which is gained by transgenic bacteria. In the past, insulin was obtained from the pancreas of pig which was not tolerated by human beings. Human growth harmones can be gained by dead bodies and sold by pharmacutical industries. These growth harmones are used in treatment of skin burns, digestive tract ulcers and bone fractures. Monoclonal antibodies and vaccines ( eg malarial vaccine SPF-66 ) are also produced by transgenic microbs.
Many organs and tissues have been clonned to save the lives of the patients dying due to disturbance in any organ. Tamoxifen ( medicine for breast cancer ) has been produced by genetic engineering.
In organs clonning, organ is made by stem cells and its identical copies are made in tissue culture in laboratory. Gene therapy is also genetic application in which bad genes are replaced with good genes. Many heart and autoimmune disorders have been cured by this process.
Whole genome screening is done to diagnose early if any genetic problem is present by using different types of genetic probes and early medicines are given to prevent or treat the patient ( eg in case of Tay Sach’s disease and sickle cell anemia ).
We can facilitate a patient suffering from a genetic disorder and increase its lifespan ( eg in case of cystic fibrosis ), by doing infusion therapy ( intravenous or subcutaneous medicines as well as injections ). Early detection of genetic disease stop the occurance of its more severe form.
Prenatal testing ( check fetal abnormalities in the uterus before birth ) also help in early detection of genetic disease. Chorionic villus sampling (CVS ) and amniocentesis are methods of prenatal testing. In CVS biopsy of villi present on placenta is taken for testing, needle may be inserted through abdomin or cervix. In amniocentesis amniotic fluid is taken and tested. By both processes we find the genome sequence of fetus or any numerical or structural abnormality of chromosomes.
Chronic villus sampling Forensics:
DNA fingerprint of every human being is different because of the difference in their genome. This technique is also called DNA profiling, different sequences of DNA bands formation occur for different people.DNA of a person is scanned at thirteen different DNA regions. It is helpful to identify people when they die due to any natural disaster ( eg. tsunami ). DNA on bones and teeth is matched with DANA samples on toothbrush and hairbrush of the nearby area or relatives of missing people.
Government has the record of database of all DNA sequences of public. It also helps to identify a criminal ( eg. rapist ). The crime scene DNA and DNA of a suspect, both are compared. If same type of banding pattern is formed then the suspect is the criminal. This technique also helps adopted people to seek their biological parents.
The following is the process of DNA profiling:
- DNA which is to be analysed is processed with restriction enzymes.
- This DNA is run on gel electrophoresis due to which DNA bands are formed.
- To gain these bands physical we perform southern blotting, DNA bands are transferred from gel to membrane ( nitrocellulose or nylon ).
- Radioactively labelled probes are added which hybridize DNA at specific regions.
- We put radiation sensitive film on blotting thus radioautograph is formed.
Thus, we gain DNA sequence bands.
In Aquaculture we farm the fish, oysters, algae and other water bodies. Due to genetic engineering, there is a great development in this field. The production and growth rate has been insreased. Now fish can tolerate stressed conditions (eg. hypertonic environment ). They can resist different types of diseases. Transgenic zebrafish has been produced which glow in water, its name is glofish. Due to large scale production, the cost of fish has been improved.
Transgenic microbs are uesd for environmental remediation in which they the environment free from pollutants, they can also degrade oil ( eg. in ponds dangerous for fish ) from environment. We can use these microbs in minning process for metal extraction ( eg. gold, copper, uranium etc ) to make ornaments or for scientific purpose.
In metagenomics, we sequence all the DNA of a particular habitat especially for those microbs which we can not culture in laboratory (greater than 99% ). The main target places for metagenomics are soil, insect gut, garbage etc. We match these sequences with known gene sequences . We can identify either a disease is infectious or not. Thus it helps in disease identification.
Harmful Effects of Genetics:
During development when we insert a gene in fetal genome it may have pleiotropic effects due to which morphological and neurological problems may occur which result in increased risk of cancer ultimately cause abortion. In embryonic stage if transgene is inserted at wrong place it can cause lack of eye or inner ear development. Transgene may become silenced after its insertion due to many molecular processes. In gene therapy vectors are mostly viruses, if they bind with strong promoter it can cause rapid division of cells resulting in cancer. If transgene replaces normal gene then there is a loss of function of normal gene due to which many metabolic processes get disturbed which can be seen in phenotype in some cases when gene is very essential.
When antibiotic resistance gene is inserted in plant then it comes in fruits or vegetables, after its ingestion by man it can cause damage.
Another disadvantage of Genetics is Genetic determinism i-e we can not remove the effects of inborn disease. We can minimize effects of mutated gene but can not eradicate it completely.
Genetic discrimination is a point at which people are judged on the basis of their genome. For example, insurance companies give insurance of those people whose all genes are healthy and no diseased gene is present. Similarly, companies give jobs to those people whose genes tell that their intellectual level is high.
Genetic privacy and confidentiality is also very significant. It is very important for doctor to keep all the information about the patient behind the curtain. To patient information can lower the self esteem of the patient. Patient becomes dishearted. There are many psychological problems which start after knowing the risk of occurance of a particular genetic disease ( eg. Huntington’s disease ). That patient becomes nervous and remains in anxiety conditions for his whole life.
In selective breeding method we mostly do in breading due to which genetic diversity among individuals is finished. These organisms can not tolerate environmental disaster and removed by the process of natural selection.
When gene from Brazil nuts was inserted in the soybean to increase its protein part then it became allergic to its eaters.
Genetically modified organisms require cultivation in soil with low productivity. They can cause unpredicted allergic reactions. Genetically modified organisms are less nutritious. These organisms can disrupt ecosystem. Thus public health comes on risk.
Clonning of Dolly sheep caused disadvantage of pre-mature aging. Mostly clonned mice and cows die suddenly after birth due to large sized heart.
To study genetic abnormalities, experiments are done on animals, injuries and death of animals may result thus there are many ethical issues related to it.
We can not obtain informed consent in case of animal testing. Some people are of the view that we have no right to harm the animals. Some experiments on animals result useless with no significant result.
Prenatal testing may result in abortion. But abortion is strictly prohibited in some religions especially in Islam. Human dignity is harmed.
Fingerprinting has also its drawbacks. Due to samples contamination or other laboratory manual or technical problems false positive results may occur. For genetic research many procedures require expensive apparatus.
Genetics has revolutionized the world. We can not deny the importance of Genetics. We enjoy a lot of benefits due to genetic applications in different fields of life but its negative effects can not be overlooked. Scientists should do more research to overcome its bad effects and explore more things.