Gel electrophoresis is a technique used to separate mixtures like DNA and proteins. The separation is based on how positively or how negatively charged a molecule is, and its size. Gel electrophoresis uses a gel (like gelatin) and an electric field is put through the gel.
The word electrophoresis comes from –electro, because an electric field is used, and –phoresis, which means movement.
The gel is made up of large and branched molecules called polymers. The amount of branches in the gel determines how easily molecules can squeeze through, depending on their size.
If there are a lot of branches, small molecules will be able to move through easily while big molecules will move through slowly or not at all. If there are few branches, both big and small molecules can move through more easily.
If a large molecule has a big charge, its attraction to the opposite charge is also large. But, since the molecule is large, it will have a difficult time moving through the thick gel. In gel electrophoresis, large molecules are going to move slower.
A small charged molecule will move through the gel more easily. Shorter molecules move faster and move further than longer ones because shorter molecules get through the pores of the gel more easily. This phenomenon is called "sieving".
If the molecule does not have any charge, it will not move.
After the gel has been run by applying the electric field, you can look to see where the molecules have moved to. To do this, different stains can be applied to the gel: this allows the molecules to be seen. The stain makes the places where the molecules moved to appear as colored bands. Stains that are used to look at proteins, such as Coomassie blue, can often been seen by the human eye under normal light. Stains that are used to look at DNA, such as ethidium bromide and GelGreen, can only be seen with the help of an ultraviolet lamp.
Gel electrophoresis is the most commonly used technique to study DNA. DNA is a very large molecule that contains genetic information. DNA can be broken down to smaller pieces of different sizes and these pieces are then separated using gel electrophoresis. DNA always has a negative charge, and moves towards the anode.
Proteins are large and complex molecules made of amino acids. Proteins can be studied by gel electrophoresis in two ways. One way is to take a mixture of proteins and separate them in the gel. The other way is to break down a single protein into smaller pieces. The smaller pieces can then be separated in the gel. Proteins can be positively or negatively charged. To separate proteins by size only, protein mixtures can be coated with a chemical called sodium dodecyl sulfate (SDS) to give all proteins a negative charge before putting the mixture into the gel.
In medicine, there is a special type of electrophoresis called iontophoresis. Iontophoresis uses the same idea of gel electrophoresis to deliver drugs into the human body through the skin without using needles to inject the drug.
Heinrich Schliemann
Heinrich Schliemann (January 6, 1822, in Neubukowin, Germany - December 26, 1890, in Naples) was a German archaeologist. He is famous for his work in discovering the ancient city of Troy.
Heinrich Schliemann was born in Neubukowin, Germany. His father, Ernst Schliemann, was a minister. His mother, Luise Therese Sophie Schliemann, died in 1831 when Heinrich was 9 years old. When his mother died, Heinrich lived with his uncle in Neustrelitz. He went to a grammar school in the town for about a year. His father paid the school fees. Heinrich was very interested in history and was encouraged by his father to read history books. After he left school, he worked in a shop in Fürstenberg for about five years. He worked hard as an apprentice, but he continued to read in his spare time.
He was not able to work as an archaeologist at this time, so he moved to a company which imported and exported products. In this job, he visited many different countries around the world, and learnt to speak English, French, Dutch, Spanish, Portuguese, Swedish, Italian, Greek, Latin, Russian, Arabic, and Turkish. His ability to speak languages was very important in his job. He later studied Latin and Ancient Greek in Paris.
In 1850, Heinrich's brother, Ludwig Schliemann, died, having got rich in the California Gold Rush. He moved to Sacramento, where he opened a bank, just like his brother. The new bank bought gold dust and sold it on to make money. In six months, the bank bought and sold millions of dollars of gold dust.
Heinrich married his wife, Ekaterina, in 1852, but the marriage was troubled. Ekaterina kept encouraging her husband to make more money, but Heinrich felt that they were rich enough.
Nobody knows how Heinrich became an archaeologist, but he continued to travel to see famous historical icons around the world. He even disguised himself to get into Mecca, the holy Muslim city. He became very interested in Troy, which was involved in a big dispute at the time. He was inspired by many people in the city, especially Ferdinand Fouqué and Frank Calvert, who he met in 1868.
Many reports have said Heinrich buried a 'treasure' he found in Troy, dubbed Priams gold.
Cyclone Nargis
Cyclone Nargis was a tropical cyclone. It was the first in the Indian Ocean in 2008. It was categorized as a Category 4 storm. It made landfall (went on land) in Myanmar (Burma) in April and May 2008. It was possibly one of the worst storms to have hit the country.
The United Nations estimated in its report that 1.5 million people were severely affected by this cyclone. Officially at least 78,000 were killed with 58,000 not found (missing); the figures however are still rising, and 80,000 were reported dead in just one town. After the disaster, the Burmese government has called for help in dealing with the situation. Some people say the government is having problems coping with the situation.
More recent reports from the government say that about 80,000 have died. Some non-governmental organizations estimate that the final number will be well over 100,000. Certain aid workers that came into the country estimate that 2 to 3 million are homeless, in the worst disaster in Burma’s history. They say it is comparable with the 2004 Indian Ocean tsunami. Andrew Kirkwood, country director of a British charity organisation said:""We're looking at 50,000 dead and millions of homeless. I'd characterise it as unprecedented in the history of Burma. [It has had about the same effect as] the tsunami on individual countries. There might well be more dead than the tsunami caused in Sri Lanka."" The United Nations says that up to 2.5 million people need help upgentltly. According to the same report, access to the affected regions has been cut off. The Red Cross says there could be up to 128,000 dead.
The storm caused the government to declare the five regions as disaster areas. - Yangon, Ayeyarwady, Bago Divisions, Mon and Kayin States. Thousands of buildings were destroyed; in the town of Labutta, located in the Ayeyarwady Division, state television reported that 75% of buildings had collapsed, and 20% had their roofs ripped off. It is believed that the cyclone is the deadliest tropical cyclone in the world since Hurricane Mitch in 1998, which killed about 18,000 people. At least 10,000 people have been reported to have died in the delta town of Bogale.