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RNA and Transcription. II. RNA. There are three key differences between RNA and DNA RNA is single stranded : DNA is double stranded RNA is made of the sugar Ribose – DNA is made of deoxyribose
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II. RNA • There are three key differences between RNA and DNA • RNA is single stranded : DNA is double stranded • RNA is made of the sugar Ribose – DNA is made of deoxyribose • RNA has Uracil instead of Thymine – Both DNA and RNA have four nitrogen bases the difference is U vs T
RNA • RNA has the job of copying DNA • The goal of RNA is to create proteins • There are three types, each with a different job. • mRNA – Messenger RNA-copies DNA to take it out in the cytoplasm • rRNA – Ribosomal RNA-works on matching mRNA - to create the amino acids in the correct order • tRNA – Transfer RNA- gives amino acids to rRNA to produce the protein.
III. Transcription • Creates a single RNA strand instead of a double DNA strand. • Creates mRNA that can move out into the cytoplasm for the next step.
Genetic Code with mRNA • In mRNA, three nitrogen bases together form a code – this is called a codon. • Looking ahead: • This code is matched with an amino acid. • A string of amino acids form a protein.
Genetic Code with mRNA • Some codons code for information other than amino acids • UAA is an example of a stop codon. • AUG is an example of a start codon. • NOTE: For every one codon, there is only ONE amino acid that can join.
Transcription • Transcription Animation
