With the beginning of civilizations and human settlements, the consumption of food by the human population increased and thus, the need to preserve excess foods became essential for survival. Since then, many traditional and household methods of food preservation have evolved to limit food spoilage. Such as cooking, the addition of spices and fermentation. Continue reading 11 Methods of Food Preservation used by Food Industry
All posts by Vinod Thakur
What are Antitranspirants? How do they Reduce Water Loss in Plants?
Antitranspirants are substances applied to the plants for the purpose of reducing transpiration (water loss) without causing a significant effect on other plant processes, such as photosynthesis & growth. They have been used with some success in horticulture, especially in the ornamental industry. Continue reading What are Antitranspirants? How do they Reduce Water Loss in Plants?
Free Radicals: What is their role in making us old?
From the beginning of time, people have tried to understand aging and processes associated with the biology of aging. Many scientists believe that aging results from the repetitive damage caused to our body cells. The everyday metabolic activities that usually sustain our life but also create “metabolic stress”, which over time, results in damage to our bodies. Some of these metabolic activities result in the production of radicals and which may cause harmful damage to our body cells. Continue reading Free Radicals: What is their role in making us old?
What are SNPs? Why are Scientists interested in them?
A most common and important source of genetic variability is known to be present uniformly throughout the genome is termed Single Nucleotide Polymorphisms or SNPs. Interest in SNPs lies in the fact that these polymorphisms may be responsible for the differences in disease susceptibility, drug metabolism and response to environmental factors between individuals. Even, if they are not directly responsible for the disease, they serve as genetic markers for a nearby locus that might be responsible. Continue reading What are SNPs? Why are Scientists interested in them?
How a 2 meters long DNA is fitted into a 2 micrometers Nucleus?
An average Human cell (diploid) contains about 6.4 billion base pairs of DNA divided among 46 chromosomes. The length of each base pair is about 0.34 nm. Therefore, if the DNA molecule in a diploid cell were laid out end to end, the total length of DNA would be approximately 2 meters. Continue reading How a 2 meters long DNA is fitted into a 2 micrometers Nucleus?
How do Bacteria become Resistant to Antibiotics?
Bacteria often become resistant using different kinds of mechanisms. One kind of mechanism is never confined to any specific class of antibiotics. Different resistance mechanisms are used in different bacteria to confront the same antibiotics.
Continue reading How do Bacteria become Resistant to Antibiotics?
What are Emerging and Re-Emerging Diseases?
Fifty years ago people believed that the war of humankind against infectious diseases was virtually over. They thought that science had won over diseases such as pneumonia, whooping cough, polio, and smallpox with the help of antibiotics, vaccines, and some aggressive public health campaigns. But, after the 1980s, emerging and re-emerging diseases have caused havoc.
In the last 30 years, at least, a dozen new diseases have emerged and traditional diseases that were gone are re-emerging. In these years, the world has seen the global spread of AIDS, the resurgence of Tuberculosis, and the appearance of new enemies like hantavirus pulmonary syndrome, hepatitis C and E, Ebola virus, Lyme disease, etc.
What are Emerging Diseases?
Emerging diseases are the diseases that
- Have not occurred in humans before. This type of emergence is very rare.
- Have occurred previously but affected only small numbers of people in isolated places. For example, AIDS and Ebola Hemorrhagic Fever.
- Have occurred throughout human history but has only recently been recognized as a distinct disease due to a causative agent. For example, Lyme disease and Gastric Ulcers.
So, we can conclude that the emerging diseases are the diseases caused by some newly identified and previously unknown causative agents.
What are Re-emerging Diseases?
Re-emerging diseases are the diseases that once were major health problems globally or in a particular country and then declined dramatically, but are again becoming a health problem for a significant proportion of the population. Malaria, tuberculosis, cholera, pertussis, influenza, and gonorrhea are some examples of re-emerging diseases.
What are factors contributing to the emergence of diseases?
Several factors are contributing to the emergence and re-emergence of diseases. Some of them are listed below.
1. Climate and Environmental Changes:
Humans are cutting trees and clearing natural habitats on a very large scale. This has forced wild animals to come closer to human habitats. This displacement has increased the possibility for causative agents to breach the species barrier between animals and humans.
For example, Lyme disease, Hantavirus Pulmonary Syndrome (HPS), Lassa fever all emerged when humans began encountering the arachnid vector (For Lyme disease) or rodent host (for HPS and Lassa fever) of the causative agents in greater number than ever before.
Global Warming is also indirectly responsible for the outbreak of diseases. This is because global warming leads to unpredictable and extreme climatic changes such as floods, tsunami, cyclones, etc. These changes then help in the rapid transmission of diseases such as malaria, dengue, cholera, etc.
2. Uncontrolled Urbanization and Population Displacements:
Urbanization often crowds humans and increases exposure to microbes. Crowding of the population leads to unsanitary conditions and also hinders the effective implementation of adequate medical care. Thus, enabling more widespread transmission and propagation of pathogens.
For example, the re-emergence of diseases such as diphtheria and whooping cough (Pertussis) is related to inadequate vaccination of the population.
Land Development and the exploration or destruction of natural habitats have increased the likelihood of human exposure to new pathogens and may put selective pressure on pathogens to adapt to new hosts and changing environments.
For example, the spread of Lyme diseases in New England probably was due to the ecological distribution that eliminated predators of deer. An increase in the deer population and deer tick populations provided a favorable situation for pathogens to spread among humans.
3. Human Behavior and Activities:
The food processing and supply centers, which carry out processes such as handling, cutting, refrigeration of food, and other treatments have the potential of becoming breeding grounds for foodborne microbial diseases.
For example, the emergence of diseases such as hemolytic uremic syndrome was related to the consumption of raw or uncooked beef and unpasteurized apple juice.
The unnatural and unprotected sexual practices have also created a higher risk of getting infected with sexually transmitted diseases(STDs). Diseases like AIDS (Acquired Immune Deficiency Syndrome), Gonorrhea, and Syphilis spread through unprotected sexual practices.
4. Antimicrobial Drug Resistance:
The key factor responsible for the rise in drug-resistant pathogens has been the excessive or inappropriate use of antimicrobial drugs or therapy. Moreover, the indiscriminate use of broad-spectrum antibiotics has also led to antimicrobial drug resistance.
For example, Tuberculosis has re-emerged due to the evolution of the causative bacteria. The bacteria have acquired resistance to the antibiotics used to treat Tuberculosis (either through mutation or genetic exchange).
Immunosuppression, either by another disease agent such as the AIDS virus or by drugs taken upon organ transplantation, increases the number of individuals susceptible to new pathogens.
Also Read: How do Bacteria become Resistant to Antibiotics?
So, now you know what is emerging and re-emerging diseases? And, what are the various factors contributing to their emergence and re-emergence? So that is all for now, meet you in my next article. Keep Reading, Keep Exploring, and Keep Sharing your Knowledge, and above all BE CURIOUS. 🙂
Also Read:11 Things Parents should know about giving Antibiotics.
References:
- (US), National, and Biological Study. ‘Understanding Emerging And Re-Emerging Infectious Diseases. National Institutes of Health (US) (2007): n. pag. Web. 3 Oct. 2015.
Why Nature Preferred DNA over RNA?
It is a well-known fact that DNA acts as genetic material in most of the organisms on this planet earth. However, it is also clear that RNA also acts as genetic material, but only in some viruses (for example, Tobacco Mosaic Viruses, QB Bacteriophage, etc.).
What does it take to be a genetic material?
Genetic material should fulfill the following criteria.
- Replication: It should have the ability to replicate itself.
- Stability: It should provide stable storage for genetic information.
- Evolution: It should have the ability to evolve and change itself.
- Expression: It should be able to express the information when needed.
Now, we have the eligibility criteria for the genetic material. Let us now examine each requirement one by one and compare DNA and RNA for these functions.
Which is better at Replication?
Replication occurs when a strand acts as a template for the synthesis of new complementary strands. This is possible only when there is the presence of complementary base pairing between the two strands of nucleic acids. We already know that the complementary base pairing is present in both the nucleic acids i.e. DNA and RNA. Thus, both of them have the ability to direct their duplications.
However, DNA has an upper hand in replication, as it can replicate with very high accuracy. This is because on average there occurs only one mistake per every 109 & 1010 bases of DNA.
Which is better in Stability?
The genetic material should be stable so that genetic information can pass from one generation to another without any change during the different life stages of the organism. Now, let us see which one is more stable? DNA or RNA.
If we recall the two basic chemical differences between DNA and RNA, then we get these two differences:
1. The presence of a 2’-Hydroxyl (-OH) group on RNA.
RNA, however, is a stable molecule due to the presence of a negative charge (–ve) on the sugar-phosphate backbone. It protects RNA from attack by Hydroxyl ions (OH–) or else it would lead to Hydrolytic cleavage. But, the presence of the 2’-Hydroxyl (-OH) group makes the RNA susceptible to Base-catalyzed hydrolysis.
Moreover, A single-stranded RNA is also prone to Auto-Hydrolysis. This spontaneous cleavage reaction takes place in basic solutions where free hydroxyl ions can easily deprotonate the 2’-Hydroxyl (-OH) group of the Ribose sugar.
However, if this 2’-Hydroxyl (-OH) group is removed from the ribose sugar then the rate of such base-catalyzed hydrolysis is decreased by approximately 100 fold. Thus, the presence of the 2’-Hydroxyl (-OH) group on every nucleotide of RNA makes it labile and easily degradable.
2. The presence of Thymine at the place of Uracil in DNA.
The only structural difference between Thymine and Uracil is the presence of a methyl group in Thymine. This methyl group facilitates the repair of damaged DNA, providing an additional selective advantage.
Cytosine in DNA undergoes spontaneous deamination at a perceptible rate to form Uracil. For example, under typical cellular conditions, deamination of Cytosine to Uracil (in DNA) occurs in about every 107 Cytidine residues in 24 hours, which means 100 spontaneous events per day.
The deamination of Cytosine is potentially mutagenic because Uracil pairs with Adenine and this would lead to a decrease in G≡C base pairs and an increase in A=U base pairs in DNA of all cells. Over the time period, the Cytosine deamination could eliminate G≡C base pairs.
But, this mutation is prevented by a repair system that recognizes Uracil as foreign in DNA and removes it. Thus, the methyl group on thymine is a tag that distinguishes thymine from deaminated cytosine. But, if DNA normally contains Uracil, recognition would be more difficult.
So, we can say that the presence of Thymine in place of Uracil in DNA enhances the accuracy of genetic messages. This makes DNA is more stable than RNA.
Which is a better option for Evolution?
To act as a better genetic material, one needs to provide the scope for slow and gradual changes (i.e. evolution). Among nucleic acids, both DNA and RNA can mutate or change their sequence. But, RNA being more unstable mutate at a faster rate.
However, many pieces of evidence suggest an intimate link between rapid mutations and the process of aging and carcinogenesis. That means rapid mutations can be carcinogenic and leads to faster aging. This may be the reason for the shorter lifespan of viruses as they mutate and evolve.
However, DNA does mutate, but at a very slow rate under normal cellular conditions which do not prove to be harmful in the longer run.
Which is better in Expression?
Expression of genetic information is also a necessary criterion that should be fulfilled by genetic material. Between both nucleic acids, RNA can directly code for the synthesis of proteins, hence, can easily express the characters.
DNA, however, is dependent on RNA for the synthesis of proteins (translation). Over the period of evolution, the protein-synthesizing machinery has evolved around RNA. Thus, RNA can easily express itself in the form of proteins.
So in the above battle between DNA and RNA, DNA is proved to be victorious and can be declared as a better genetic material as it can
- Replicate with more accuracy.
- Store information with better stability.
- Undergoes slow changes and can resist rapid ones (mutations).
But, for the expression of genetic information DNA needs RNA for protein synthesis, which is then transcribed from the DNA sequence.
So from the above discussion, we can conclude that DNA is a better genetic material than RNA. Also, we can conclude that DNA is preferred for the storage of genetic information, whereas RNA is better in the transmission of genetic information 🙂. So that is all for now, meet you in my next article. Keep Reading, Keep Exploring, and Keep Sharing your Knowledge, and above all BE CURIOUS. 🙂
References:
- ‘Biochemistry Revisited: Why Is DNA (And Not RNA) A Stable Storage Form For Genetic Information?’. N.p., 2015. Web. 25 Sept. 2015.
- Wikipedia, ‘RNA Hydrolysis’. N.p., 2015. Web. 25 Sept. 2015.
Who discovered that DNA is the Genetic Material?
The discovery of DNA as the genetic material was one of the major achievements of science in the 20th century. This discovery made DNA, the chemical basis of heredity. It took almost 80 years for scientists to prove that DNA is the genetic material.
Read more: Who discovered that DNA is the Genetic Material?
Early works:
In 1869, Johann Friedrich Miescher, a young Swiss medical student, discovered an acidic substance that he isolated from pus cells obtained from bandages used to dress humans. He found it in the form of a mixture of compounds in the nucleus of the cell and named it “Nuclein”.
The nature of Nuclein was unusual as it contained large amounts of both nitrogen and phosphorous. At that time these two elements were coexisting only in certain types of fats. The discovery of Nuclein by Friedrich Meischer was quite early. Whereas it took a very long time to discover and prove that DNA is the genetic material.
By 1926, the quest to determine the mechanism for genetic material had reached the molecular level. In addition to this, different discoveries and findings further narrowed the search for the genetic material to the chromosome levels. But, the key genetic molecule was still missing from the research and findings.
Griffith’s Experiment: Transforming Principle
In 1928, Fredrick Griffith, an English microbiologist, transformed nonpathogenic forms of Streptococcus pneumoniae into pathogenic forms by changing their physical forms. He accomplished this transformation through the following steps:
He injected mice with a mixture of heat-killed S strain (pathogenic) and live R strain (non-pathogenic) pneumococci. The mice died, and he recovered the live S strain of pneumococci from the blood of mice. That means heat-killed pathogenic strain transformed non-pathogenic live strain into pathogenic forms.- But, when he injected live R strain (non-pathogenic) and heat-killed S strain separately, the mice lived. This is because none of them were pathogenic.
He concluded that heat-killed virulent S strain transferred some “transforming principle” to the non-virulent R strain, which enabled it to become virulent. This must be due to the transfer of genetic material.
In 1931, Richard Sia and Martin Dawson performed the same experiment in vitro, showing the mice played no role in the transformation process.
Evidence for DNA as the genetic material
For a very long time after the discovery of Nuclein, it was thought that proteins carry genetic information. Whereas, the nucleic acids were thought to have only structural functions. But somehow the search for the chemical identity of the transforming principle reached its climax in 1944.
In 1944, Oswald Avery, Colin Macleod, and Maclyn McCarty provided the first solid evidence of DNA as the genetic material. They were working on the transforming principle found in Griffith’s experiment.
They supported their evidence through the following observations:
- The transformation carried out by heat-killed S strain bacteria was inhibited, when the highly purified extract of that strain was subjected to the activity of Pancreatic Deoxyribonuclease (DNases). This is because DNAase digested DNA and hence no transformation occurred.
- They also found that Protein-digesting enzymes (proteases) and RNA-digesting enzymes (RNases) did not affect transformation. So they concluded that protein and RNA were not responsible for transformation.
Hence, they concluded that DNA is the genetic material that caused the transformation from heat-killed virulent bacteria to live non-virulent bacteria.
Hershey-Chase Experiment
The second proof that DNA is genetic material was provided in 1952 by the experiments of Alfred Hershey and Martha Chase. They worked with bacteriophage T2, a virus that infects the bacterium Escherichia coli. The T2 phage consists of a DNA core that is surrounded by a protein coat.
They labelled the nucleic acid part of the T2 phage with radioactive phosphorus and protein coat with radioactive sulfur. After that, they infected E. coli cells with labelled T2 phage. They found out that the radioactive phosphorus (nucleic acid part) remained in the cells, whereas the radioactive sulfur (protein part) was largely lost.
This showed that proteins did not enter the E.coli from the T2 phage. Therefore, it was DNA that was transferred from the T2 phage to E. coli.
Also Read: Why Nature Preferred DNA over RNA?
So, now we know that the Hershey-Chase experiment unequivocally resolved the debate that DNA is genetic material. Thus, at last, the journey of genetic material from Nuclein to DNA came to an end and DNA is genetic material, became a fact. So that is all for now, meet you in my next article. Keep Reading, exploring, sharing your Knowledge, and above all, BE CURIOUS. 🙂
Also Read: 11 Amazing Facts about DNA You didn’t Know.
11 Things Parents should know about giving Antibiotics.
Antibiotics have been around for many years and if your baby is 3 years or few months old then it is evident that you may get confronted with antibiotics 4 to 5 times in a year and may have fears and doubts about antibiotics. Moreover, many of you may have a habit of taking antibiotics on an old prescription. These habits are not good for your baby’s health. However, if antibiotics are used wisely, they can provide significant benefits. So, here I have put together 11 things that parents should know about giving antibiotics to their children.
1. Never Prescribe On Your Own.
Parents usually have a habit of self-prescribing antibiotics to their babies. This is a terrible habit and may prove harmful to the health of your baby. Always consult your doctor before taking any kind of antibiotics. Your doctor will decide what form of treatment is best suited for your baby and if prescribing an antibiotic is necessary, he will then select the one that will work best for treating your specific infection.
2. Always Complete The Medication.
Parents think that taking antibiotics for a longer period may cause some side effects to their baby. Because of this thing in their mind, they stop the medication when symptoms seem to go away. Stopping the medication may allow some of the bacteria to continue to live and become resistant to the antibiotic prescribed to your baby. This will make it more difficult to treat any subsequent infections he will acquire in the future.
3. Never Save Your Medication For Reuse.
If you think you can keep and reuse leftover antibiotics then you are totally wrong. Antibiotics should not be taken to treat any other illnesses. Do not merely take them when you feel sick. Moreover, the antibiotic that is in powder form gets expired within 7 days of their first use.
4. Prepare The Dosage Properly.
Mostly the antibiotics for infants are in the form of syrup powder, which is taken after mixing them with water. There is always a sign for measuring the volume of water to be mixed for preparing the syrup. Check this sign properly before purchasing the medicines and never exceed this level while making the syrup.
5. Ask Before Taking Antibiotics.
Some medicines come in the form of “sustained release”. Thus, you shouldn’t break or grind medicines before giving them. So, always ask your doctor before using them.
6. Always Give The Correct Dosage.
The correct dosage is a very important factor in antibiotic effectiveness. So, never measure the dosage using spoons (in the case of syrups) and remember the repetition time of the medication.
7. Discuss Drug Allergy Running In The Family.
If you, your baby, or any member of your family have any kind of drug allergy then discuss it with your doctor. The allergic reaction can produce rashes, itching, or difficulty in breathing in severe cases. Some of them can be fatal. Tell him if your baby is taking antibiotics or any medication over a very long period. It will help him in prescribing the most appropriate medication.
8. Store Them At Right Place.
Keep antibiotics away from your baby’s reach. Also, keep them away from direct sunlight and moisture. In hot weather, you can also store them in refrigerators.
9. Do Not Pressurize Him.
Many parents have a habit of pressurizing their doctor to write antibiotics in the prescription for their baby. This may be because they think that antibiotics can cure every disease. But, this is not true. Antibiotics work only against infections caused by bacteria. They do not work with viral infections, such as colds, flu, and most sore throats. Moreover, many of them don’t know that 80% of baby infections are viral which do not need antibiotics.
10. Ask Doctor About Dosage Time.
Some medicines are taken before meals and some are taken after meals. So, always ask your doctor each and every detail before leaving the clinic.
11. Sharing Is Not Good For Health.
Never share your medication with other such as eye/ear drops. Because by doing this, there is a possibility of transmission of infection or pathogenic particles, or antibiotic resistance.
So now, parents know what they need to do before giving antibiotics to their children. However, these things imply to adults also. 🙂. So that is all for now, meet you in my next article. Keep Reading, Keep Exploring, and Keep Sharing your Knowledge, and above all BE CURIOUS. 🙂
Science Samhita 