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DNA DETAILS
DNA stands for Deoxyribonucleic Acid. It is special because it holds the code for every cell in your body. That's right, every cell in your body uses DNA for an instruction manual. If you want to take away all of the importance of that statement, you can say that DNA is just a long spiral chain of nucleotides. But it's more. So much more.
So you get all of those nucleotides in two long chains that twist around each other. That twisting shape is called a double-helix. The spiral ladder has the ability to wind and unwind so that the nucleic acid chain can duplicate itself. That duplication process happens every time a cell divides.
DNA DOWN TIME
When a cell is in its normal state, the DNA is not duplicating and it just looks like a blob of white strands. The nucleic acid chains usually sit around uncoiled and as loose strands called chromatin. When it is time for the cell to reproduce, they condense and wrap up very tightly. The tightly wound DNA is called a chromosome. Chromosomes look kind of like long, limp hot dogs. They are also found in pairs.
In most organisms, you will find DNA in the nucleus. Chromosomes work with other nucleic acids in the cell to build proteins and help in duplication. You will most likely find mRNA (messenger-ribonucleic acid) in the nucleus with the DNA. tRNA (transfer-ribonucleic acid) is found outside of the nucleus, floating in the cell. In a few organisms called prokaryotes, there is no defined nucleus and the DNA is found throughout the cell.
DNA = INSTRUCTION BOOK
Just remember that DNA is the instruction manual for an organism. Even though all organisms use the same five base pairs to build DNA (purines and pyrimidines), it is the order that makes us who we are. Every organism on Earth has a different number and order of base pairs. That order determines your physiology.
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