Mrs. Deringer

Deoxyribonucleic Acid

" The basic unit of structure and function of LIFE"


The nucleus is the control center of a cell because it controls all the activities of the cell.
Inside the nucleus of a human cell are 46 chromosome The chromosomes are made of DNA. We can compare a chromosome to a ball of yarn. The ball itself is the chromosome and the yarn is the DNA.

Chromosomes contain genes. Genes are segments of Deoxyribonucleic Acid (DNA) that code for the proteins in your body. Your body is made of proteins. For example, there is a DNA code for the protein keratin. Your hair is made of keratin. The cartilage in your body is composed of fibrous protein called collagen.

DNA is made of four nitrogen bases, adenine (A), thymine (T), cytosine (C) and guanine (G). Adenine always pairs with Thymine and Guanine always pairs with cytosine.The way you look is determined by proteins.The proteins that you are made from are determined by the sequence of DNA in the nucleus.

In 1953, James Watson and Francis Crick discovered the true shape of DNA. The shape of DNA is called a double helix, which looks like a twisted ladder. The sides of the ladder are made of sugar and phosphate molecules.  The sugar is deoxyribose.

It is directly attached to the nitrogen bases.

Click on the screen to watch my powerpoint movie on Deoxyribonucleic Acid.


For life to continue, new cells need to be produced. For this to happen, DNA needs to make a copy of itself to make new cells. The new cells need to have the correct information. Then the cell can divide and the new cell will have an exact copy of the original DNA. When DNA makes a copy of itself it is called DNA Replication. The nitrogen bases of the DNA ladder are bonded by hydrogen bonds. Those bonds break and . . . .

Click on the screen to watch my powerpoint on Deoxyribonucleic Acid Replication.

Do you remember which nitrogen bases pair up together?

Click Here to be transported to an interactive web site that illustrates how a DNA model is built.



Are you ready to test your knowledge?

Click Here to take a practice quiz on DNA

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