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Griffith's Experiment
Avery and other scientists discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next.
One kind of virus that infects bacteria is known as a bacteriophage Hershey and Chase concluded that the genetic material of the bacteriophage was DNA, not protein.
SECTION ONE
The double helix structure explains how DNA can be copied, but it does not explain how a gene works. In molecular terms, genes are coded DNA instructions that control the production of proteins within the cell. The first step in decoding these genetic messages is to copy part of the nucleotide sequence from DNA into RNA, or ribonucleic acid. These RNA molecules contain coded information for making proteins.
RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary sequence in RNA, a process called transcription. Transcription requires an enzyme known as RNA polymerase that is similar to DNA polymerase. During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.
Proteins are made by joining amino acids into long chains called polypeptides. Each polypeptide contains a combination of any or all of the 20 different amino acids. The properties of proteins are determined by the order in which different amino acids are joined together to produce polypeptides.
Section Three
During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand
SECTION 2