An allergy is a medical condition that causes someone to become sick after eating, touching, or breathing something that usually has little or no effect to the average person. The Merriam-Webster dictionary defines “Allergy” as, “exaggerated or pathological immunological reaction (as by sneezing, difficulty breathing, itching, or skin rashes) to substances, situations, or physical states that are without comparable effect on the average individual. “Hypersensitivity” is defined as, abnormally susceptible physiologically to a specific agent (as a drug or antigen). In this article, a type 1 hypersensitivity reaction will be discussed in detail, as well as treatments that can help to reduce the symptoms and potentially cure the allergic reaction completely.
Type 1 hypersensitivity (aka immediate or anaphylactic hypersensitivity) may involve skin, eyes, nasopharynx, bronchopulmonary tissues, and GIT (gastrointestinal tract). The reaction generally takes 15-30 minutes to occur after exposure to the antigen. However, in some cases, it can take 10-12 hours. The symptoms can be anywhere from a minor inconvenience to death.
In a type 1 hypersensitivity reaction, an antigen (a harmful/potentially harmful substance foreign to the body) is presented to CD4 glycoprotein cells (cluster of differentiation cells) and T-helper cells. This stimulates B-cells to produce Immunoglobulin class E (IgE) antibodies specific to the antigen. IgE antibodies then bind to Fc protein receptors on the surface of mast cells and basophils (both rich in histamine and anticoagulant heparin). Mast cells and basophils are then “sensitized” so when a second exposure of the same kind of antigen occurs, this cross links the cell-bound IgE and results in the release of pharmacologically active substances. Cross-linking of IgE Fc-receptor is extremely important in mast cell triggering. Antimicrobial cytotoxic granules are released, calcium ions (Ca2+, signaling transduction) are increased, and histamine (increases the permeability of the capillaries to white blood cells and some proteins to allow them to engage pathogens in the infected tissues), prostaglandin (hormone-like lipid compounds that regulate the contraction and relaxation of smooth muscle tissue), and leukotriene (use lipid signaling to convey information to either the cell producing them or neighboring cells in order to regulate immune responses) are secreted into the surrounding tissue area. Smooth muscle contraction and vasodilation are the main effects in the overall scheme.
Standard Treatments
Type 1 hypersensitivity is classified into an immediate and late-phase reaction. The immediate hypersensitivity reaction occurs minutes after exposure and results in the release of vasoactive amines and lipid mediators. The late-phase reaction occurs 2–4 hours after exposure and includes the release of cytokines (proteins important for cell signaling which impacts cell behavior).
Diagnostic tests include skin tests (skin prick and intradermal) which measure total IgE and specific IgE antibodies against the suspected allergens. Increased IgE levels are indicative of a potential atopic condition (a genetic disposition to develop an allergic reaction and produce elevated levels of IgE upon exposure to an environmental antigen, especially one inhaled or ingested). Symptomatic treatment is given with antihistamines (these block histamine receptors). Chromolyn sodium inhibits mast cell degeneration by inhibiting calcium ion influx (research suggests). Late-phase symptoms are treated with leukotriene receptor blockers or inhibitors of the cyclooxygenase pathway. Singulair and Accolate are leukotriene receptor blockers and Zileutoin are inhibitors of the cyclooxygenase pathway.
Bronchodilators (inhalants) such as isoproterenol derivatives provide short-term symptomatic relief from bronchoconstriction. Terbutaline and Albuterol are used in this case. Hyposensitization, immunotherapy or desensitization, is a treatment for insect venoms and some pollens.
Alternative and Natural Medicine
For many years it has been believed that honey could help relieve allergies by desensitizing allergy sufferers to the pollen in the air. Many scientists argue whether or not honey has a significant impact in treating allergies. However, studies show (by Finnish researchers) that people allergic to birch pollen were able to control their allergy symptoms more than those who used mainstream allergy medication when they consumed honey that contained birch pollen.
Acupuncture has proven to help relieve symptoms and help sufferers breathe better. This has been a successful treatment for many years. However, consistent treatment is required in order to relieve symptoms. When acupuncture treatments stop, the symptoms often times will reappear.
Butterbur is known to a successful natural cure. There is strong evidence supporting its effects. The plants commonly referred to as butterbur are found in the daisy family Asteraceae in the genus Petasites. The herb works as a leukotriene inhibitor. The inhibitor will block some chemicals that cause swelling in the nasal passages. This is a natural remedy that can successfully be used in the place of Singular. Research shows that an extract of butterbur root is just as effective at relieving nasal symptoms as antihistamines like Zyrtec and Allegra. This natural remedy is safer than mainstream medications because it doesn’t cause sleepiness (a common side effects of antihistamines). Many medications are also known to make one restless and uncomfortable. Butterbur, therefore, is a safe and healthy alternative.
There are many other natural remedies that show promising results in treating allergies. Quercetin, found in many fruits and vegetables, works as a mast cell stabilizer. It helps to block histamine that causes inflammation. Studies show great results with quercetin, however, more evidence is being attained to provide more facts. There are other natural treatments that show promising results, yet, more evidence is needed to make it a fact. Some of these natural remedies include, stinging nettle, bromelain (reduces nasal swelling), phleum pratense (helps reduce eye irritation), and tinospora cordifolia (helps reduce sneezing, itching, and nasal discharge). Echinacea, grape seed extract, pine bark extract, vitamin C, cat’s claw, albizzia, baical skullcap, goldenseal, and spirulina are known to help relieve symptoms as well, but more research needs to be conducted in order to make it official.
Knowledge is Power
Understanding what exactly is happening in a type 1 hypersensitivity reaction is crucial in seeking an effective treatment. Now that we understand the process of the reaction, we are armed with sufficient knowledge to start making progress toward a cure. Lots of research is needed to be certain that a particular treatment will be successful.
Many people do not like to take mainstream medications due to the long list of side effects and the potential dangers involved in using some of the medications. Many of these medications DO help relieve symptoms, but the side effects that accompany the treatment can be just as bad as the allergic reaction itself. Albuterol, for example, is known to cause shakiness in the arms and legs and it increases the heart rate for many users. Diarrhea, headache, stomach pain, and nausea are common side effects of many allergy medications.
It is said that in nature, for every plant that causes a negative reaction that there is another plant that will balance it out and provide a cure. While modern society tends to gravitate toward innovative technology for answers, it is unwise to ignore the natural world when seeking help. The more we lose touch with nature, the more we will encounter problems.
The best way to fight against the negative effects of allergies is to embrace the wisdom of the ancients. Getting enough sleep (balanced; not too much not too little), engaging in daily exercise (especially advanced systems like Yoga, Mo Pai Nei Kung, and T’aijiquan), and maintaining a proper diet free of unhealthy chemicals (such as preservatives and artificial flavors), processed foods, and most meat, will naturally build resistance against antigens and will strengthen bodily health to such an extent that one can overcome (or significantly reduce) all allergies. To reach the pinnacle of good health one must maintain a heightened state of consciousness. The more loving, caring, happy, and positive we can be, the better our health will be.
We did some physics experiments today. These are pictures of light bending after passing through a semi-solid substance with an index of refraction similar to water 🙂
50 percent of pregnant women in developing countries lack proper maternal care, resulting in 240,000 maternal deaths annually from childbirth.3
1 out of 6 infants are born with a low birth weight in developing countries.4
Poor nutrition causes nearly half (45%) of deaths in children under five – 3.1 million children each year. That is 8,500 children per day.6
A third of all childhood death in sub-Saharan Africa is caused by hunger.5
66 million primary school-age children attend classes hungry across the developing world, with 23 million in Africa alone.6
Every 10 seconds, a child dies from hunger-related diseases.5
The Hunger Project firmly believes that empowering women to be key change agents is an essential element to achieving the end of hunger and poverty. Wherever we work, our programs aim to support women and build their capacity.
HIV/AIDS and other Diseases
35 million people are living with HIV/AIDS.7
52 percent of people living with HIV/AIDS are women.7
88 percent of all children and 60 percent of all women living with HIV are in sub-Saharan Africa.7
6.9 million children died in 2011 each year – 19,000 a day- mostly from preventable health issues such as malaria, diarrhea and pneumonia.5
Launched in 2003, The Hunger Project’s HIV/AIDS and Gender Inequality Campaign works at the grassroots level to provide education about preventative and treatment measures.
Poverty
1.4 billion people in developing countries live on $1.25 a day or less.8
Rural areas account for three out of every four people living on less than $1.25 a day.9
22,000 children die each day due to conditions of poverty.10
Rural Hunger Project partners have access to income-generating workshops, empowering their self-reliance. Our Microfinance Program in Africa provides access to credit, adequate training and instilling in our partners the importance of saving.
Agriculture
75 percent of the world’s poorest people — 1.4 billion women, children, and men — live in rural areas and depend on agriculture and related activities for their livelihood.11
50 percent of hungry people are farming families.11
In each region in which we work, The Hunger Project provides tools and training to increase farming production at the local level. In Africa, our epicenter partners run community farms where they implement new techniques while producing food for the epicenter food bank.
Water
1.7 billion people lack access to clean water.12
2.3 billion people suffer from water-borne diseases each year.12
12 percent of the world’s population uses 85 percent of its water, and none of the 12 percent lives in developing countries.13
The Hunger Project works with communities to develop new water resources, ensure clean water and improved sanitation, and implement water conservation techniques
SHORTLY after the birth of her sixth child, Mathilde went with her baby into the fields to collect the harvest. She saw two men approaching, wearing what she says was the uniform of the FDLR, a Rwandan militia. Fleeing them she ran into another man, who beat her head with a metal bar. She fell to the ground with her baby and lay still. Perhaps thinking he had murdered her, the man went away. The other two came and raped her, then they left her for dead.
Mathilde’s story is all too common. Rape in war is as old as war itself. After the sack of Rome 16 centuries ago Saint Augustine called rape in wartime an “ancient and customary evil”. For soldiers, it has long been considered one of the spoils of war. Antony Beevor, a historian who has written about rape during the Soviet conquest of Germany in 1945, says that rape has occurred in war since ancient times, often perpetrated by indisciplined soldiers. But he argues that there are also examples in history of rape being used strategically, to humiliate and to terrorise, such as the Moroccan regulares in Spain’s civil war.
As the reporting of rape has improved, the scale of the crime has become more horrifyingly apparent (see table). And with the Bosnian war of the 1990s came the widespread recognition that rape has been used systematically as a weapon of war and that it must be punished as an egregious crime. In 2008 the UN Security Council officially acknowledged that rape has been used as a tool of war. With these kinds of resolutions and global campaigns against rape in war, the world has become more sensitive. At least in theory, the Geneva Conventions, governing the treatment of civilians in war, are respected by politicians and generals in most decent states. Generals from rich countries know that their treatment of civilians in the theatre of war comes under ever closer scrutiny. The laws and customs of war are clear. But in many parts of the world, in the Hobbesian anarchy of irregular war, with ill-disciplined private armies or militias, these norms carry little weight.
Take Congo; it highlights both how horribly common rape is, and how hard it is to document and measure, let alone stop. The eastern part of the country has been a seething mess since the Rwandan genocide of 1994. In 2008 the International Rescue Committee (IRC), a humanitarian group, estimated that 5.4m people had died in “Africa’s world war”. Despite peace deals in 2003 and 2008, the tempest of violence has yet fully to subside. As Congo’s army and myriad militias do battle, the civilians suffer most. Rape has become an ugly and defining feature of the conflict.
Plenty of figures on how many women have been raped are available but none is conclusive. In October Roger Meece, the head of the United Nations in Congo, told the UN Security Council that 15,000 women had been raped throughout the country in 2009 (men suffer too, but most victims are female). The UN Population Fund estimated 17,500 victims for the same period. The IRC says it treated 40,000 survivors in the eastern province of South Kivu alone between 2003 and 2008.
“The data only tell you so much,” says Hillary Margolis, who runs the IRC’s sexual-violence programme in North Kivu. These numbers are the bare minimum; the true figures may be much higher. Sofia Candeias, who co-ordinates the UN Development Programme’s Access to Justice project in Congo, points out that more rapes are reported in places with health services. In the areas where fighting is fiercest, women may have to walk hundreds of miles to find anyone to tell that they have been attacked. Even if they can do so, it may be months or years after the assault. Many victims are killed by their assailants. Others die of injuries. Many do not report rape because of the stigma.
Congo’s horrors are mind-boggling. A recent study by the Harvard Humanitarian Initiative and Oxfam examined rape survivors at the Panzi Hospital in Bukavu, a town in South Kivu province. Their ages ranged from three to 80. Some were single, some married, some widows. They came from all ethnicities. They were raped in homes, fields and forests. They were raped in front of husbands and children. Almost 60% were gang-raped. Sons were forced to rape mothers, and killed if they refused.
The attention paid to Congo reflects growing concern about rape in war. Historically the taboo surrounding rape has been so strong that few cases were reported; evidence of wartime rape before the 20th century is scarce. With better reporting, the world has woken up to the scale of the crime. The range of sexual violence in war has become apparent: the abduction of women as sex slaves, sexualised torture and mutilation, rape in public or private.
In some wars all parties engage in it. In others it is inflicted mainly by one side. Rape in wars in Africa has had a lot of attention in recent years, but it is not just an African problem. Conflicts with high levels of rape between 1980 and 2009 were most numerous in sub-Saharan Africa, according to Dara Kay Cohen of the University of Minnesota (see chart). But only a third of sub-Saharan Africa’s 28 civil wars saw the worst levels of rape—compared with half of Eastern Europe’s nine. And no part of the world has escaped the scourge.
The anarchy and impunity of war goes some way to explaining the violence. The conditions of war are often conducive to rape. Young, ill-trained men, fighting far from home, are freed from social and religious constraints. The costs of rape are lower, the potential rewards higher. And for ill-fed, underpaid combatants, rape can be a kind of payment.
Full article: http://www.economist.com/node/17900482
How much does mental health impact physical health?
If we consider the emotional state of an individual who has just received news that a close loved one has suddenly died, most people would respond in a state of sadness and sorrow. In times of extreme grief, the impact of the mind on the body can be harsh and long lasting. In grief, despair, and sorrow, the mind is “sick.” The body naturally embodies the sickness, as a shadow follows one walking in light.
If that person were able to gain command over his or her mind, he or she would come to make peace with all reality and settle into a balanced and healthy state of mind functioning in good mental and physical health.
Cultivating a more focused mind, harmoniously aligned with the universal laws of morality, will allow greater consciousness expansion and intellectual development.
Overcoming grief requires liberation from false ideas. Letting go of all despair and finding peace is difficult for most people. Many people suffer miserably with bad health, physically and mentally.
Understanding the mysteries of life will enable people to take control of their health and well being. Knowledge is power. The truth removes the barriers of growth and allows an avenue for one to attain total freedom and liberation. Bringing our emotional minds into a harmonious balance will help us transcend all sickness. As in the example of the person receiving news of a loved one’s death, this person may fall into extreme despair and this can lead to destruction. However if one knew that no one really dies, then one would have no need to fall into a state of extreme despair/suffering.
Maintaining regular exercise will help one begin to regulate and balance the bodily system. Focusing on good health and being disciplined will provide an opportunity for positive change. When done in a harmonious manner, exercise will help one rise up from despair and relax. Most people suffer from varying degrees of stress and all the reasons for it. Being aware of this, the way to overcoming it is to focus on regulating all stress through elimination and balancing the mind in equanimity. Relaxing all tension, letting all stress go. Gently and with grace.
Understanding the difference between the body and the mind will allow one to attain a greater command of one’s health if one is disciplined enough to maintain discipline. It requires work, not too much, not too little.
Aligning one’s mind with the living power that sustains all life will allow one to begin to know the creator of reality and this leads to the highest end. It is mighty and powerful, and it is silent and elusive.
Do you believe it’s possible that SOMETHING created the universe and all existence? Is it possible that a power greater than the universe exists?
-“yes, God is the creator of all existence, God alone commands all…”
-“How did the universe come into existence? That’s a hard one, but evidence suggests that the giver of life is controlling the universe, which makes it a greater power than the universe.”
-“SOMETHING HAD to have made life!! Louis Pasteur disproved spontaneous generation of microorganisms, life doesn’t arise from nothing. The universe too, didn’t arise from nothing. The SOMETHING that brought the universe into existence is what most people in America refer to as GOD. The universe came from SOMETHING. That something is a power greater than the universe and what is known to mankind.”
-“How did we get here? I think the answer is so BIG that we would have difficulty wrapping our minds around it.”
-“I definately believe it’s possible. At our core we are but the light of consciousness. A power gives life to that light.”
-“Our people believe that the power that gives life is alive and we communicate with it and we give thanks for life and all the blessings of life. We live our lives in thanks and gratitude. It is a power that is greater than the universe…”
-“יהוה alone gives life to the universe. יהוה alone has power over all.”
The whole purpose of education is to educate. Therefore it is for educators to focus on EFFECTIVE methods of instruction. If teachers are not providing adequate instruction, then the students will not receive the guidance they need. Accurate and properly presented instruction is essential. This review will briefly touch on implementing instruction and models of instruction, and it will include my thoughts and reflection.
There is always a way. This holds true in all areas of life. Sometimes the way is hidden and unknown, but there is always a way. In order to find the way, one must open one’s mind to all possibilities. When planning instruction, we need to be sure the information is accurate and we need to be sure that the manner in which our instruction is presented is one that is designed to maximize the students’ ability to learn.
Conducting class takes great care and precision. It begins with a pure and loving heart that genuinely wants to help everyone. With this nature and intention, we need to be sure we are extra patient and extra focused and extra disciplined.
We need to do everything we can to help the students help themselves. In the grand scheme of things, it is up to every individual to accomplish for one’s self. As educators, we need to help our students in every way we can to learn, grow, and evolve. It is not for educators to just regurgitate information to the students without feeling. Part of being human is being emotional and sensitive. Therefore, as educators, we need to understand the human psyche and acknowledge that people are steadily “awakening” to greater depths of consciousness. We need to be aware of this reality when teaching and adjust for it accordingly. A two year old baby is in a lesser developed state of consciousness than a forty year old adult whose state of consciousness (under healthy conditions) is much more developed. With that said, we can understand the gradual expansion of consciousness over time. With these factors and more, we need to present our instruction in a manner that will provide the best results and help the student in the best way possible. This should be the goal of every instructor of knowledge.
If one wishes to improve one’s health, there are many things one can do. One may choose to eat more fruits and vegetables in order to improve health and nothing more. This WILL improve health (as long as the fruits and veggies are fresh and pure, ideally organic, and free of pesticides and other toxins). Another person may choose to do the same AND include drinking more water, taking vitamins, herbs, and “superfoods” such as, raw organic honey, goji berries, cocoa, cordyceps and more. This too will improve one’s health, even more than only eating more fruits and veggies. THEN there’s the person who chooses the same healthy diet with all superfoods AND this person chooses to do push-ups, sit-ups, pull-ups and squats everyday along with weightlifting. This person, when exercising properly (in a healthy and balanced manner), will be EVEN MORE healthy than the first two people! The next person then decides to take it to the next level and do all the things the third person did and adds to it, Tai Chi, Yoga, Chi Gung, meditation, and running. With this example, we can see how some people put in greater effort than others. Successful educators work hard (with great effort to do the best) to teach every student with care and precision, which yields greater success.
Honey, that delectable condiment for breads and fruits, could be one sweet solution to the serious, ever-growing problem of bacterial resistance to antibiotics, researchers said in Dallas today.
Honey could be one sweet solution to the serious, ever-growing problem of bacterial resistance to antibiotics, researchers said in Dallas* today. Medical professionals sometimes use honey successfully as a topical dressing, but it could play a larger role in fighting infections, the researchers predicted.
“The unique property of honey lies in its ability to fight infection on multiple levels, making it more difficult for bacteria to develop resistance,” said study leader Susan M. Meschwitz, Ph.D. That is, it uses a combination of weapons, including hydrogen peroxide, acidity, osmotic effect, high sugar concentration and polyphenols — all of which actively kill bacterial cells, she explained. The osmotic effect, which is the result of the high sugar concentration in honey, draws water from the bacterial cells, dehydrating and killing them.
In addition, several studies have shown that honey inhibits the formation of biofilms, or communities of slimy disease-causing bacteria, she said. “Honey may also disrupt quorum sensing, which weakens bacterial virulence, rendering the bacteria more susceptible to conventional antibiotics,” Meschwitz said. Quorum sensing is the way bacteria communicate with one another, and may be involved in the formation of biofilms. In certain bacteria, this communication system also controls the release of toxins, which affects the bacteria’s pathogenicity, or their ability to cause disease.
Meschwitz, who is with Salve Regina University in Newport, R.I., said another advantage of honey is that unlike conventional antibiotics, it doesn’t target the essential growth processes of bacteria. The problem with this type of targeting, which is the basis of conventional antibiotics, is that it results in the bacteria building up resistance to the drugs.
Honey is effective because it is filled with healthful polyphenols, or antioxidants, she said. These include the phenolic acids, caffeic acid, p-coumaric acid and ellagic acid, as well as many flavonoids. “Several studies have demonstrated a correlation between the non-peroxide antimicrobial and antioxidant activities of honey and the presence of honey phenolics,” she added. A large number of laboratory and limited clinical studies have confirmed the broad-spectrum antibacterial, antifungal and antiviral properties of honey, according to Meschwitz.
She said that her team also is finding that honey has antioxidant properties and is an effective antibacterial. “We have run standard antioxidant tests on honey to measure the level of antioxidant activity,” she explained. “We have separated and identified the various antioxidant polyphenol compounds. In our antibacterial studies, we have been testing honey’s activity against E. coli, Staphylococcus aureus and Pseudomonas aeruginosa, among others.”
*This study was presented the 247th National Meeting of the American Chemical Society (ACS).
Eating organic food protects from pesticide exposure
Filed Under: Pesticides Organics Health Children
Children who switched to eating organically-grown food greatly reduced their exposure to organophosphate insecticides. Scientists from Seattle and Atlanta just published the results of their study which linked pesticides in children’s urine to pesticide residues on food. Scientists worry that organophosphates might harm children’s developing nervous systems.
Children who switched to eating organically-grown food greatly reduced their exposure to organophosphate insecticides. Scientists from Seattle and Atlanta just published the results of their study which linked pesticides in children’s urine to pesticide residues on food. Scientists worry that organophosphates might harm children’s developing nervous systems.
Twenty-three elementary-aged children participated in a 15 day study which was divided into three parts. First the children ate their usual diet of conventionally-grown food for 3 days. Then they were switched to organically-grown substitutes for 5 days. For the final 7 days, they switched back to conventional food.
The organic substitutes were mainly fruits, vegetables, juices, and grain products (such as wheat) because these foods are often contaminated with organophosphates.
Urine samples were collected twice a day for each child. Researchers tested the urine for signs of pesticides.
In the case of two organophosphate insecticides — malathion and chlorpyrifos — the results were startling. Signs of these two chemicals were found in the urine in the first part of the study. Almost immediately after the children switched to an organic diet, these chemicals could not be detected. The chemicals showed up again when the children switched back to their normal diet.
The researchers said “We were able to demonstrate that an organic diet provides a dramatic and immediate protective effect against exposures to organophosphorus pesticides that are commonly used in agriculture.”
More information on chlorpyrifos
The organophosphate family of chemicals damages the nervous system (which includes the brain), so scientists are particularly concerned about children’s exposure because their bodies are still developing. Chlorpyrifos is one of the many insecticides in this chemical family.
In 1999, the Environmental Protection Agency decided to start cancelling some uses of chlorpyrifos, in part because of some disturbing animal studies. For example, newborn rats were much more susceptible to toxic effects of chlorpyrifos than adults. Also, even low doses of chlorpyrifos caused structural changes in the development of the brain.
While chlorpyrifos has been greatly restricted for uses in and around homes, it is still widely used in agriculture. The study described above makes it clear that children are still exposed to chlorpyrifos from residues on food.
A brief introduction to: DNA (deoxyribonucleic acid)
In 1928, British scientist Fredrick Griffith was trying to learn about how certain types of bacteria produce a serious lung disease known as pneumonia. He isolated two slightly different types of pneumonia bacteria from mice.
In the lab…
disease strain – grew into smooth colonies on the culture plates
harmless strain – produced colonies with rough edges
(easy to distinguish due to different appearances)
This led to biologists realizing that genetic information could be transformed from one bacterium to another.
In 1944, a group of scientists led by Canadian biologist Oswald Avery at the Rockefeller Institute in New York decided to repeat Griffith’s work. They did this with the intention of finding what it is that causes the transformation.
they took the heat-killed bacteria and destroyed proteins, lipids, carbohydrates, and other molecules, including the nucleic acid RNA. Transformation still occurred. When they then destroyed the DNA, transformation did not occur.
Through this experiment they discovered that the nucleic acid DNA stores and transmits genetic information.
In 1952, two American scientists, Alfred Hershey and Martha Chase collaborated in studying viruses (nonliving particles smaller than a cell that can infect living organisms). One type of virus that infects bacteria is a “bacteriophage” (“bacteria-eater”). Bacteriophages are composed of DNA or RNA inside of a protein body. When a bacteriophage enters a bacteria, the virus attaches to the surface of the cell and injects its bacteria.
[T2 bacteriophage (tan) invading an E. coli cell (green)].
Radioactive markers helped the scientists determine which part of the virus entered the infected cell which led them to discover that genes were made of DNA, not protein.
Because proteins contain very little phosphorus and DNA contains no sulfur, the scientists grew viruses in cultures containing radioactive isotopes of phosphorus-32 and sulfur-35. The radioactive substances were used as markers.
* If sulfur-35 was found in the bacteria, then the viruses protein was injected into the bacteria.
* If phosphorus-32 was found in the bacteria, then it was the DNA that had been injected into the bacteria.
The Hershey-Chase experiment concluded that the genetic material of the bacteriophage was DNA!
After this, scientists wanted to know more!
Genes…
1) carry information from one generation to the next.
2) they determine the heritable characteristics of organisms
3) all of a cell’s genetic information is replicated every time a cell divides (mitosis).
DNA (deoxyribonucleic acid)
DNA is a long molecule made of nucleotides.
Each nucleotide is made up of three basic components:
* a 5-carbon sugar called deoxyribose
* a phosphate group
* a nitrogenous (nitrogen containing) base >>>> there are 4 kinds of nitrogenous bases in DNA: adenine, thymine, guanine. and cytosine.
The backbone of a DNA chain is formed by sugar and phosphate groups of each nucleotide.
Scientists concluded that the four different nucleotides could be strung together in many different ways, so it was possible they could carry coded genetic information.
*** Years earlier, an America biochemist named Erwin Chargaff discovered that the percentages of nucleotides are equal in any sample of DNA.
A=T
G=C
A British scientist named Rosalind Franklin used a technique called X-ray diffraction to get information about the structure of the DNA molecule. Aiming a powerful X-ray beam at concentrated DNA samples, she recorded the scattering pattern of the X-rays onto film.
*** When an American Biologist named James Watson was shown a copy of Franklin’s X-ray pattern in 1953, he, along with British physicist Francis Crick, built a structural model that explained how DNA could carry information and how it could be copied. The published their results in April 1953.
Watson and Crick’s model of DNA was a double helix. (two strands are wrapped around each other)
The Double Helix
A double helix is shaped like a spiral staircase. Watson and Crick then discovered that hydrogen bonds could form between certain nitrogenous bases and provide enough force to hold the two strands together. Nitrogenous based can only form between adenine and thymine, and guanine and cytosine. This principle is called base pairing. This brought Chargaff’s rules full circle. For every adenine there had to be one thymine. For each cytosine molecule, there was one guanine molecule.
derekcheyyim 