1. 2.7, Translation

2. The Genetic Code
A. Bases are read 3 at a time
1. mRNA = codon
2. tRNA = anti-codon

3. B. Each codon codes for a specific amino acid (ex. CCU = proline) 1
B. Each codon codes for a specific amino acid (ex. CCU = proline) 1. More than 1 codon for each amino acid C. Universal – same in ALL species

5. II. Types of RNA involved
mRNA – messenger
Complimentary to a gene, carries message from the nucleus to ribosomes
(made during transcription)
rRNA – ribosomal
Component of ribosomes, made in the nucleolus
tRNA – transfer
Brings amino acid to the ribosome to build a polypeptide

6. A. tRNA 1. Forms a t shape because parts are complimentary with itself

7. 2. Activation – attaching an amino acid

8. a. Bottom portion of tRNA contains an anti-codon that is complimentary to codon on mRNA b. Anti-codon determines which amino acid is attached to 3’ end of tRNA c. 20 different enzymes responsible – one for each amino acid d. Requires ATP

9. Structure of a ribosome
A. Consist of a large & small subunit
1. mRNA fits in between
2. Each made of rRNA (2/3) and proteins (1/3 of mass)

10. B. Molecules constructed in nucleolus and exit through nuclear pores

11. C. 3 Sites A Site Holds tRNA carrying next amino acid P Site
Holds tRNA carrying growing amino acid
E Site
Deactivated tRNA exits ribosome

12. Initiation
A. Small subunit moves along mRNA until it finds start codon (AUG)
1. Activated tRNA with anticodon UAC combines with mRNA (hydrogen bonds form)

13. B. Large subunit binds to form translation initiation complex 1
B. Large subunit binds to form translation initiation complex 1. Also involves initiation factors - proteins that join complex C. Requires energy from GTP

14. Elongation
A. tRNAs bring amino acids to ribosome 1 at a time
B. Elongation factors – proteins that assist tRNA binding to mRNA at A Site

15. C. Translocation – tRNAs move from one site to the next (A  P  E) 1
C. Translocation – tRNAs move from one site to the next (A  P  E) 1. Bond holding amino acid to tRNA in P site breaks and a new bond forms between amino acid on tRNA in P site and amino acid in A site

16. 2. Empty tRNA moves into E site and leaves ribosome a
2. Empty tRNA moves into E site and leaves ribosome a. Float around in cytoplasm to find proper amino acid and be reactivated D. Ribosome moves along mRNA in 5’  3’ direction!

17. Termination
A. Stop codon on mRNA moves into A site
B. Release factor – protein that fills the
A site with no amino acid to attach to growing chain

18. 1. Catalyzes hydrolysis between tRNA in P site and polypeptide chain 2
1. Catalyzes hydrolysis between tRNA in P site and polypeptide chain 2. Polypeptide is released and ribosome breaks apart into 2 subunits