Transcript Slide 1
RNA • Stands for “Ribose Nucleic Acid” • Single stranded • Contains a ribose sugar • Uracil instead of thymine, so adenine bases with uracil RNA’s Purpose • To take information on how to build a protein and assemble amino acids accordingly • How?: Assembles amino acids in a long chain which is used to code for proteins 3 Types of RNA • mRNA: Messenger RNA – brings information from the DNA in the nucleus to the cytoplasm • rRNA: Ribosomal RNA – clamp onto the mRNA and use it to assemble the amino acids in the correct order • tRNA: Transfer RNA – transports the amino acids to the ribosome to be assembled into a protein. Transcription • Process in the cell nucleus when enzymes make an RNA copy of a DNA strand • Same process as DNA replication; with some differences: • RNA molecule is single-stranded (rather than double stranded in DNA) • Uracil instead of Thymine. So in RNA Adenine binds with Uracil Transcription… • Where it takes place: • Prokaryotic cell – in the cytoplasm • Eukaryotic cell – in the nucleus, then it moves to the cytoplasm Transcription DNA backbone mRNA DNA backbone We know that amino acids are the building blocks for proteins … But how do we get amino acids from mRNA? The Code • Biochemists started to break the genetic code when they realized that 3 nucleotides code for an amino acid! – This is known as a CODON • Amino acids are considered the code that converts the language of mRNA to our proteins The Code…. • 20 amino acids total • 64 different mRNA codons in the genetic code • All organisms have the same genetic code for amino acids and proteins • Important Codons: 1. Start: AUG 2. Stop: UAA, UAG, & UGA Amino Acid Chart How to Read the Amino Acid Chart • Start on the left side with the first letter of the codon • Then find the second letter of the codon along the top of the chart • Then, on the right side, find the corresponding last letter of the codon You Try It!! • Which amino acid do the following codons code for? – CUU – GAC – UAC – CAU – UAG – UGA • Which codons would code for the following amino acids? – Methionine – STOP – Glycine – Arginine – Histine – Proline