DNA and RNA

History of DNA 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.

DNA, Proteins, and Amino Acids DNA stores information Proteins are large molecules that are made up of chains of amino acids (building blocks of proteins) 20 different amino acids come together in enough combinations to make up the thousands of different proteins found in the human body DNA stores the information that enables a cell to put together the right sequences of amino acids needed to produce specific proteins DNA contains a code which holds the rules and symbols used to carry information and how to produce proteins

DNA and the Genetic Code 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 4 nitrogen bases: adenine (A), thymine (T), cytosine (C), guanine (G) Due to differences in size and shape, the nitrogen bases will always pair with the same each time: adenine-thymine (A-T) and cytosine-guanine (C-G) The sequence or order is very important because it is this sequence that determines the proteins being made

Replication When DNA is copied before a cell divides, the process is called replication

RNA RNA, or ribonucleic acid is the molecule that carries the information from DNA to a ribosome where the amino acids are brought together to form a protein RNA structure is similar to DNA structure “sides” of the ladder are made of a sugar called ribose and a phosphate group The “rungs” of the ladder are 4 nitrogen bases: adenine (A), cytosine (C), guanine (G), uracil (U) Uracil replaces thymine, so adenine pairs with uracil (A-U) and cytosine pairs with guanine (C-G) 3 types of RNA and they are named for their functions messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)

Transcription The process of transferring information from DNA to RNA is called transcription During transcription, DNA is used as a template to produce a single strand of RNA When transcription is complete, the RNA is released, it does not stay attached to the DNA

Translation Replication and transcription involve passing along information that is coded in the language of nucleotide bases The actual assembly of the amino acids in the proper sequence is translation and it takes place in the cytoplasm of the cell