1. RNA, Transcription, and the Genetic Code

2. RNA = ribonucleic acid -Nucleic acid similar to DNA but with several differences DNARNA Number of strands21 Type of sugarDeoxyriboseRibose Nucleotides UsedA, G, C, and TA, G, C, and U (Uracil) *Uracil replaces Thymine in RNA and base pairs with Adenine!

3. Types of RNA: 1.Messenger RNA (mRNA) - carries DNA message out of nucleus to ribosomes 2. Ribosomal RNA (rRNA) - found in ribosomes 3. Transfer RNA (tRNA) - contain anti-codons used in translation, brings amino acid to ribosome

4. Transcription = process of making an mRNA strand from DNA -Similar to replication but remember, RNA is single stranded not double stranded. -Enzyme involved is called RNA polymerase.

5. Steps: 1.Initiation -RNA polymerase binds to promoter region of DNA strand. -Promoter = region of DNA that signals the start of a gene 2. Elongation -RNA polymerase creates a 5’ to 3’ mRNA strand using DNA as a template.

6. Steps: 3. Termination -RNA polymerase reaches end of DNA sequence that codes for gene (Termination sequence) and releases mRNA into nucleus. Transcription Animation

8. Before mRNA strand is sent out of the nucleus. Non-coding parts need to be taken out through RNA splicing. Introns= Non-coding segments, taken out Exons= Coding segments, spliced together mRNA Splicing Video

10. * Proteins are made when mRNA molecule travels out of nucleus to cytoplasm to ribosomes. Proteins are mode by joining amino acids together into long chains called polypeptides. Order of amino acids determines the properties of the protein.

11. A, G, C, and U bases of RNA form a “language” called the Genetic Code. It is universal Codon = every three letters on an mRNA strand.

12. * Genetic code is degenerate since 64 different combinations of letter code for only 20 different amino acids. That means that most amino acids can be specified by more than one codon. Important codons are start and stop: Start = AUG Stop = UAA, UGA, UAG