1. THE THREE TYPES OF RNA

2. Section 11.2 Summary – pages 288 - 295 There are three main types of RNA that help build proteins. # 1 Messenger RNA (mRNA) brings instructions from DNA in the nucleus to the ribosomes. Like a contractor that takes the blueprints from the architect to the construction site

3. Section 11.2 Summary – pages 288 - 295 # 2 Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids (the monomers of proteins) to the ribosome to be assembled into a polypeptide. Amino Acid How it binds with mRNA

5. Section 11.2 Summary – pages 288 - 295 # 3 Ribosomes are made of Ribosomal RNA (rRNA). rRNA uses the instructions from mRNA and the supplies from tRNA to assemble a polypeptide.

6. A-site is where the tRNA binds to bring the AMINO ACIDS P-site is where the growing POLYPEPTIDE is kept. E-site is where the tRNA exits after it drops off it’s amino acid.

7. 1. mRNA brings the instructions. 2. tRNA supplies the amino acids. 3. rRNA facilitates the tRNA and mRNA joining to form polypeptide chain. RIBOSOME

8. THE PROCESS OF TRANSLATING

9. Protein Synthesis

10. Section 11.2 Summary – pages 288 - 295 Why does mRNA have to be made? (Why can’t DNA deliver it’s own instructions) Nucleus

11. Transcription Cap Added Tail Added Splice out introns Mature mRNA, ready to go!

12. Section 11.2 Summary – pages 288 - 295 Every three letters on a mRNA strand, called a codon, is a code for a specific amino acid (a building block to make protein) The Genetic Code

13. Each codon codes for a specific amino acid. CODON CHART Every three letters on an mRNA strand is a codon. Things to notice: There are 64 possible codon combinations There are only 20 different amino acids Most amino acids correspond to more than one codon

14. Translation Changing from nucleic acid language to amino acid language. The second step of protein synthesis, in which a polypeptide chain is built at a ribosome.

15. WHAT DOES TRANSLATION LOOK LIKE IN THE CELL?

16. Section 11.2 Summary – pages 288 - 295 The 5’ ‘capped’ end of an mRNA strand attaches to a ribosome. Step 1: mRNA strand

17. Section 11.2 Summary – pages 288 - 295 Step 2: Initiation AUG is the first codon on the mRNA strand. This signals the ribosome to START making a protein. The tRNA with anti-codon UAC, holding a Methonine A.A. binds at the P-site.

18. Section 11.2 Summary – pages 288 - 295 tRNAs bring amino acids to the ribosomes. tRNA’s role RIBOSOME mRNA Coming from Nucleus

19. Each tRNA only carries one amino acid. Amino acid

20. Section 11.2 Summary – pages 288 - 295 There are also three nucleotides on the bottom of the tRNA called an anti-codon. Anti-codons complementary base pair with the codons on mRNA. (this is to make sure they are bringing the correct amino acid- If the anti-codon doesn’t base pair with the codon, then the wrong amino acid was brought) Anti-codon

21. After the first tRNA binds with the codon AUG, the ribosome reads the next codon at the A-site, and the complementary tRNA brings the correct amino acid. A C G U G C threonine

22. Step 3: Elongation Refers to the time between the beginning and end of translation in which the polypeptide is being built- amino acid by amino acid… The amino acid(s) are transferred to the new tRNA molecule in the A- site. A peptide bond is formed to add the new amino acid to the chain.

23. Step 3: Elongation, cont.

24. The mRNA slides down. The tRNA with the growing polypeptide is now in the P-site. The ‘empty’ tRNA exits the ribosome from the E- site.

26. Step 4: Termination A polypeptide chain is formed until a stop codon is reached. Signaling the end of Translation. A release factor binds to the stop codon and adds a water molecule instead of an amino acid.

27. Hydrolysis occurs, freeing the finished polypeptide.