Mitosis happens in all types of dividing cells in the human body except with sperm and ova. The sperm and ova are gametes or sex cells. The gametes are produced by a different division method called meiosis.
There are five phases of mitosis. Each phase is used to describe what kind of change the cell is going through. The phases are prophase, prometaphase, metaphase, anaphase and telophase.
During prophase, chromatin (tangled-up DNA) in the nucleus condense into chromosomes (bunched-up DNA). Pairs of centrioles move to opposite sides of the nucleus. Spindle fibers begin to form a bridge between the ends of the cell.
During prometaphase, the nuclear envelope around the chromosomes breaks down. Now there is no nucleus and the sister chromatids are free. A protein called a kinetochore forms at each centromere. Long thin proteins reach across from opposite poles of the cell and attach to each kinetochore.
During metaphase, the pair of chromatids are aligned by the pushing and pulling of the attached kinetochore microtubules, similar to a game of "tug of war". Both sister chromatids stay attached to each other at the centromere. The chromosomes line up on the cell's equator, or center line, and are prepared for division. This is the longest phase of mitosis.
During anaphase, the sister chromatids split apart and move from the cell's equator (metaphase plate) to the poles of the cell. The kinetochore is attached to the centromere. The microtubules hold on to kinetochore and shorten in length. Another group of microtubules, the non-kinetochore microtubules, do the opposite. They become longer. The cell begins to stretch out as the opposite ends are pushed apart.
Telophase is the final stage in mitosis: the cell itself is ready to divide. One set of chromosomes is now at each pole of the cell. Each set is identical. The spindle fibers begin to disappear, and a nuclear membrane forms around each set of chromosomes. Also, a nucleolus appears within each new nucleus and single stranded chromosomes uncoil into invisible strands of chromatin.
Cytokinesis, even though it is very important to cell division, is not considered a stage of mitosis. During cytokinesis, the cell physically splits. This occurs just after anaphase and during telophase. The cleavage furrow, which is the pinch caused by the ring of proteins, pinches off completely, closing off the cell.
The cell now has reproduced itself successfully. After cytokinesis, the cell goes back into interphase, where the cycle is repeated. If cytokinesis were to occur to a cell that had not gone through mitosis, then the daughter cells would be different or not function properly. One would still have the nucleus and the other would lack a nucleus. Cytokinesis is different in both animals and plant cells. In plant cells, instead of splitting into two halves, it forms a cell plate. This is a cell wall that forms between the two nuclei after they have split apart. This must happen because the cells have a rigid shape, and must be completely covered in the cell wall to function.
Inflammation
Inflammation is the first reaction of the immune system to an infection or irritation. First the organ involved gets red, then it will get hot, then it will swell, and then it will hurt. Finally it will stop working. The first four of these reactions have been known for a long time, since Antiquity. Finding them is attributed to Celsus. The last one was added by Rudolf Virchow in 1858.
Inflammation can also be present/responsible for skin disorders such as psoriasis/dandruff, joint pains, arthritis etc.
Car rental
Car rental is when you rent a car. The company providing you the car becomes the car rental service provider, whereas you become the car hirer, as you hire the car for a fee.
A car rental agency or a rent-a-car (car hire in British English) is a company that rents automobiles for short periods of time (ranging from a few hours to a few weeks) for a fee.
They can be found primarily located near airports or busy city areas. The internet is changing the car rental industry with companies that are now called online car rental companies. Travelers can pre-book their rental car online anywhere across the globe directly from the service providers like Hertz, Budget, Alamo, , Thrifty, Travelauto.com, Dollar, Enterprise Rent-A-Car and Europcar.
Car rental agencies are mainly for people who need a car for a short period of time, for example travellers who are out of town, people whose cars were damaged or destroyed. Car rental agencies may also rent trucks for self-moving industry
Car rentals are subject to many conditions which vary from one brand to another. The vehicle must be returned in a good condition and must not exceed a maximum driven distance, otherwise extra fees may be incurred. Additionally, some companies set up a minimum age for the vehicle driver, which in some cases is as high as 25, even in countries where the minimum legal age to hold a driver's license is much lower. Recent conditions have used GPS technology to limit maximum speeds or driving to specific regions.
North America and Europe are leading the car rental market, followed by Asia-Pacific. North America is dominating the car rental market, owing to the high usage rate of car rental services by daily commuters, office-goers, and tourists in the country. Also, the growing trend of car sharing also boosts the usage of car rental in this region.
Mechanical engineering
Mechanical engineering is a branch of engineering that applies the principles of Mechanics and Materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It involves the production and usage of heat and mechanical power for the design, production, and operation of machines and tools. They can range from building a rocket ship down to things as small as an integrated circuit. It is one of the oldest and broadest engineering disciplines.
Paul Newman
Paul Leonard Newman (January 26, 1925 – September 26, 2008) was an American actor. He was born in Shaker Heights, Ohio. His mother was a Slovak; his father was a Jew who had one parent from Hungary and the other from Poland. Although Paul Newman was not a Jew by Orthodox Jewish standards he considered himself Jewish and would have been accepted as one by other Jewish movements.
He was known especially for the 1969 movie "Butch Cassidy and the Sundance Kid". He played Butch Cassidy in the movie. He was married to actress Joanne Woodward. He died of lung cancer in 2008.
Newman retired from acting in May 2007. He said "You start to lose your memory, you start to lose your confidence, you start to lose your invention. So I think that's pretty much a closed book for me."
He came out of retirement to narrate the 2007 documentary movie "Dale", about the life of NASCAR driver Dale Earnhardt. He also narrated the 2008 BBC documentary "Meerkats: The Movie". It was recorded at a studio near his home shortly before his death. "The Meerkats" was the last movie credit of Newman's long career.
IRA
IRA may mean:
Piccadilly line
The Piccadilly line is a line of the London Underground. It is coloured dark blue on the Tube map. It is the fifth busiest line on the Underground network judged by the number of passengers transported per year. It is mainly a deep-level line, running from the north to the west of London via Zone 1. However, there are a number of surface sections mostly in its westernmost parts. Out of the 53 stations served, 25 are underground. It is the second longest line on the system, after the Central Line.