by Sara, Gr.6

DNA is one of the largest known molecules.

If you think of one molecule of sugar, a DNA

molecule is

weighs 100,000 times more than that. In normal

weight (the way we normally think of things), a

DNA molecule is actually very light. Even one

quintillion DNA molecules weighs three ounces!

DNA molecules are cramped tightly

inside the cells

that hold them because if they were completely

straight they would be several thousand

times the length of the cell!

DNA consists of two long thin strands that are

wound around each other to form a

spiral. This is

called a double helix

(check your dictionary for this

term!). The strands of a

double helix

are made up of a large amount of chemical

building blocks called bases.

Every strand of DNA contains about

twelve billion

individual bases. Since there are

four different types of

bases, A, G, C, and T, various

sequences of different

arrangements of bases can occur. The

strands of a helix are held together by

weak chemical bond between nearby

strands. The G base will

only pair up with the C base and the A base will

only pair up with the T base( for example, C

can't pair with a G

base). So, if you put it all together, you have DNA.