1. GOOD MORNING! HAPPY TUESDAY!

2. WARM UP FOR TUES 10/28/14 ADV BIO 1. What is an anticodon and what is its function? 2. How do ribosomes assist protein synthesis? 3. What would happen if a genetic mutation occurred at a start codon? 4. What happens while tRNA is present at “A SITE”? “P SITE”?

4. WARM UP FOR TUES 10/28/14 BIO 1. Use words to explain what transcription is. Now draw a simple diagram. 2. What does RNA polymerase do? 3. What is the role of the promoter in making a copy of RNA? 4. Differentiate between introns and exons.

5. From RNA to proteins: Translation

6. The Central Dogma  DNA-> mRNA-> tRNA->amino acids-> protein  TRANSCRIPTION: from DNA to mRNA  TRANSLATION: from mRNA-> protein

7. mRNA contains the “message”  RNA contains information (copy of genetic code from DNA)  Process of copying DNA to RNA (transcription) is edited:  Bits of mRNA are removed before final molecule is assembled ( introns )  What remains is an mRNA composed of multiple pieces ( exons ) joined together.

8. Introns and Exons

9. CODONS  mRNA is read 3 base pairs at a time, this is called a codon.  Each codon codes for a specific amino acid.

10. TRANSLATION: THE STEPS  1. mRNA brings the “message” from the nucleus to the ribosome in the cytoplasm  2. Ribosome attaches to the mRNA and begins translation at the start codon. mRNA is “fed” through the ribosome one codon (3 bases) at a time.  3. Transfer RNA (tRNA) molecules carry amino acids to the ribosome. The tRNA (and amino acid) is specific to the codon on mRNA.

11.  tRNA has 3 unpaired bases called an anticodon that pair specifically with the codon sequence of mRNA

12. TRANSLATION: THE STEPS  4. tRNA molecules move through the ribosome. Amino acids are linked together. Empty tRNA discarded.  Translation stops at a stop codon. The protein (amino acid sequence) and mRNA are released from the ribosome.

13. Translation in Action (video)

14. “Translation is like a train”  mRNA is the railroad track  tRNA is the railroad car  Amino acids are the cargo in the railroad car

15. Predicting amino acid sequences  Using a table and base pairing rules for DNA and RNA, we can predict what amino acids are expected from a DNA sequence, or from an RNA sequence.  For example: ATA (DNA) -> UAU (mRNA codon)-> AUA (tRNA anticodon) the tRNA with this anticodon carries the amino acid Tyrosine

16. Amino acid/ mRNA codon tables