Presentation Transcript

1. DNA Transcription & Translation • Bio 6B: Explain replication, transcription, and translation using models of DNA and ribonucleic acid RNA TranscriptionTranslation DNA mRNA Protein occurs in nucleusoccurs on ribosome

2. DNA Transcription • The word transcribe means “to copy”. During transcription, the genetic information code is copied into a single strand of mRNA. mRNA is known as “messenger” RNA because it carries the DNA code or message out of the nucleus and into the cytoplasm. • DNA cannot travel out of the nucleus but RNA can. • RNA contains the base Uracil instead of Thymine.

3. Transcription Activity: Transcribe the DNA strand on your handout into a strand of mRNA. REMEMBER: Uracil is in a RNA strand instead of Thymine. Example: DNA: TACACGATT mRNA: AUGUGCUAA

4. Translation • In order for translation to begin, mRNA must first attach itself to a ribosome which is found in the cytoplasm of a cell. The information in mRNA is organized into three-letter blocks called codons. Codons are like words of the RNA message.

5. Codon Activity • Organize your mRNA into three letter blocks called codons. • Example: • mRNA: AUGUGCUAAG • AUG UGC UAC Three letter blocks = codons

6. Codons • Each codon codes for a specific amino acid in the protein chain. tRNA (transfer) matches a particular codon to a particular amino acid. Amino acids are joined together in the correct sequence to form a protein chain.

7. How do I read a Codon chart? • “First letter” represents the first letter of a codon. Example: AUG • “Second letter” represents the second letter of a codon. Example: AUG • “Third letter” represents the third letter of a codon. Example: AUG • The amino acid coded for the codon AUG is methionine. It’s your turn to practice using the codon chart! Identify the amino acids represented by the codons on your handout.

8. Codon chart activity Use your codon chart to identify the amino acids coded in your mRNA strand.