In term 3 this year, Mrs Koh, has once told us about the "magic" of stem cells, which is that it can actually change into almost any cells in your body. Therefore, today, I am going to elaborate on it.
Stem cells are biological cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into diverse specialized cell types and can self-renew to produce more stem cells. Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components. Therefore, a stem cell basically receives signals and they then differentiate into the cell that it should be, for example, red blood cells, skin cells et cetera.
Several adjectives are used to describe the number of cells they can differentiate into, or the development potential of the cell.
1)Totipotent- Basically a stem cell that can become ANY cell in our body.
2)Pluripotent- Basically a stem cell that can become ALMOST ANY cell in our body.
3)Multipotent- Basically a stem cell that can differentiate into a limited range of cell types.
There are generally a few types of stems cells and the below is their names and information:
1) Early Embryonic Stem Cells- This group of stem cells are called embryo and is produced when the newly fertilised egg starts to divide.
2) Blastocyst Embryonic Stem Cells- Seven days after fertilization of the egg, the embryo forms a blastocyst. The embryos in blastocyst stage contains two types of cell. The embryonic stem cells would later develop into the foetus and the trophoblast cells would develop into the placenta eventually.
3) Fetal Stem Cells- After eight weeks, the embryo is referred to as the foetus. The stem cells in the foetus are in charge of the initial development of tissues before birth.
4) Umbilical Cord Stem Cells- The job of the umbilical cord is to transport nutrients and oxygen-rich blood from the placenta to the foetus. The blood from the umbilical cord contains stem cells genetically identical to the baby.
5) Adult Stem Cells- Although its name is "Adult" Stem Cells, it is also present in infants and children. This stem cells reside in already developed tissues, directing their growth and maintenance throughout life.
So, WHERE might we find them? Since we are not able to get stem cells from the embryo, blastocyst, foetus, therefore, we can only get the UMBILICAL CORD STEM CELLS and the ADULT STEM CELLS.
Thlere are three accessible sources of autologous adult stem cells in humans:
1)Bone marrow, which requires extraction by harvesting, that is, drilling into bone (typically the femur or iliac crest),
2)Adipose tissue (lipid cells), which requires extraction by liposuction, and
3)Blood, which requires extraction through pheresis, wherein blood is drawn from the donor (similar to a blood donation), passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.
Stem cells can also be taken from umbilical cord blood just after birth.
A lot of diseases can be cured through the proper use of stem cells, for example, leukemia. Therefore, I believe that there will always be a way, if you have the will. At first, no one has any knowledge of stem cells but eventually, we not only know what they are but how to use them so that it is beneficial. I really admire the scientists of their intelligence and perseverance and how they use them to serve the world.
A lot of diseases can be cured through the proper use of stem cells, for example, leukemia. Therefore, I believe that there will always be a way, if you have the will. At first, no one has any knowledge of stem cells but eventually, we not only know what they are but how to use them so that it is beneficial. I really admire the scientists of their intelligence and perseverance and how they use them to serve the world.
Adapted from:
http://t3.gstatic.com/imagesq=tbn:ANd9GcQeTsVxrYNVBMAORrcvv_k_hj6_gEiPRLQBOPZUqucUqUMMgzLpNj8_AUN
Sources: http://learn.genetics.utah.edu/archive/stemcells/sctypes/
http://t3.gstatic.com/imagesq=tbn:ANd9GcQeTsVxrYNVBMAORrcvv_k_hj6_gEiPRLQBOPZUqucUqUMMgzLpNj8_AUN
Sources: http://learn.genetics.utah.edu/archive/stemcells/sctypes/
Mercury
This is a common element in Chemistry and now, I am going to elaborate on this element.
As all of us know, Mercury is a heavy, silvery white metal, a chemical element and its chemical symbol is Hg, also known as quicksilver. Mercury, together with Bromine, are the only elements in the liquid state in standard conditions for temperature and pressure. With a freezing point of -38.83 degree Celsius and a boiling point of 356.73 degree Celsius, it has one of the narrowest ranges of its liquid state in all metals. Mecury is a poor heat conductor and a good electricity conductor.
Applications-
- It was originally used as a dental amalgam but later, now that the toxic effects of mercury are more widely understood, the use of mercury as dental amalgam has been reduced to very rare.
- Mercury is also used for thermometers, barometers, mano meters et cetera, however, due to its toxic effect and when spilled could cause severe consequences, mercury equipments have been largely phased out and alcohol-filled, galinstan-filled or digital thermometer et cetera are now more widely used.
- Mercury is also known to be in make-ups. Mercury, as thiomersal, is widely used in the manufacture of mascara.
As all of us know now, Mercury is poisonous but HOW does it poison us or kill us?
- Most of us get Mercury poisoning when we consume fish. HOW? This is because there is Mercury in the bodies of all livestock and plants and when the level of Mercury is over the safety standards, we get poisoned and may die. An example would be whale meat, whereby when tested, is 20 times the acceptable standard of Mercury level in Japan.
- Also, Mercury is also present in the atmosphere. Half of it comes from us humans. HOW? Atmospheric Mercury is released through coal plants, waste disposal, gold production et cetera.
- As Mercury and its chemical compounds is often involved in the making of light bulbs, explosives, batteries which are commonly found almost anywhere(except explosives), and Mercury and its chemical compounds can be readily absorbed through our bare or insufficiently protected skin.
- Damage to brain, kidney and lungs.
- Acrodynia(Pink Disease)
- Minamata Disease
- Et cetera
The phenomenon is called a convex meniscus.
It is due to what is called cohesion and adhesion. The water molecules are attracted to each other through cohesion, which is the attraction between similar particles (by polarity). Adhesion is attraction between unlike molecules. When water is placed in a glass container, the forces of cohesion overcome the forces of adhesion, and the water climbs up the glass.
Conversely, the attraction between mercury atoms (cohesion) is stronger than its attraction to the glass (adhesion). Therefore, the atoms pull together and away from the glass.
Adapted from: http://wiki.answers.com/Q/Why_is_the_meniscus_of_water_concave_and_the_meniscus_of_mercury_is_convex#ixzz2649kIRSO
Conversely, the attraction between mercury atoms (cohesion) is stronger than its attraction to the glass (adhesion). Therefore, the atoms pull together and away from the glass.
Adapted from: http://wiki.answers.com/Q/Why_is_the_meniscus_of_water_concave_and_the_meniscus_of_mercury_is_convex#ixzz2649kIRSO
Adapted from:http://www.isa.org/Images/InTech/Nov2002/20021121.gif
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