ACOS 10 Identify differences between deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Examples: DNA—double helix, contains thymine; RNA—single stranded, contains uracil  Identifying Watson and Crick as scientists who discovered the shape of the DNA molecule

DNA which is short for deoxyribonucleic acid is a chemical code in a cell’s hereditary material that contains information for an organism’s growth and function.

When a cell divides, the DNA code is copied and passed to the new cells so the new cell receives the same coded information as the original.

In 1952, scientist Rosalind Franklin discovered that DNA is two chains of molecules in a spiral form which is referred to as a double helix.

In 1953, scientists James Watson and Francis Crick made a model of a DNA molecule. According to Watson and Crick’s DNA model, each side of the ladder is made up of a sugar called deoxyribose and a phosphate group.

The rungs of the ladder are made up of other molecules called nitrogen bases.

The four kinds of nitrogen bases found in DNA are: Adenine (A) Guanine (G) Cytosine (C) Thymine (T)

In DNA adenine always pairs with thymine, and guanine always pairs with cytosine.

When chromosomes are duplicated before mitosis the amount of DNA in the nucleus is doubled.

DNA Duplication: The two sides of DNA unwind and separate. Each side then forms a new side which is identical to the original.

Gene- a section of DNA on a chromosome where instructions for making specific proteins is found. Genes are found in the nucleus but proteins are made on the ribosomes in the cytoplasm so the code has to be sent there.

RNA is short for ribonucleic acid which carries codes for making proteins from the nucleus to the ribosomes. The sugar- phosphate molecules in RNA contain the sugar ribose and not deoxyribose like in DNA.

RNA is made in the nucleus on a DNA pattern but looks like a ladder that has its rungs sawed in half. RNA has the bases A, G, and C like DNA but has the uracil (U) instead of thymine (T).

In RNA adenine always pairs with uracil, and guanine always pairs with cytosine.

If DNA is not copied exactly, the proteins made from the instructions might not be made correctly. Mutations are any permanent change in the DNA sequence of a gene of a cell. Outside factors such as X rays, sunlight, and some chemicals have been known to cause mutations.