1. 1 Review How does a cell interpret the genetic code Explain What are codons and anticodons 2 Review What happens during translation Compare and Contrast How is protein synthesis different from DNA replication 3 Review Why is the genetic code considered universal Infer In what way does controlling the proteins in an organism control it’s characteristics 4 Choose one component of translation. Write a question about that component and use it to form a hypothesis that could be tested in an experiment

2. Ch 13 RNA and Protein Synthesis
13.2 Ribosomes and Protein Synthesis

3. Proteins are made from long chains of amino acids or polypeptides
20 different amino acids
Order of amino acids make proteins different.

4. Codon Each three-letter “word” in mRNA
Consists of three consecutive bases that specify a single amino acid.

5. How to Read Codons
Four different bases in RNA, so 64 possible three- base codons (4×4×4 = 64)
To read a codon, start at the middle of the circle and move outward.

7. Starts with AUG
Has three stop codons.

8. Translation Decoding of an mRNA message into a protein
From RNA to protein
Different languages.

9. Translation Steps
mRNA is transcribed in the nucleus and then enters the cytoplasm for translation.

10. Ribosome attaches to an mRNA molecule
Ribosome reads each codon of mRNA
Directs tRNA to bring the specified amino acid
Ribosome then attaches each amino acid to the growing chain.

11. tRNA has three unpaired bases or anticodon which is complementary to one mRNA codon
Codon AUG
Anticodon UAC.

12. Next codon is UUC
tRNA molecule with an AAG anticodon brings the amino acid to ribosome.

13. Ribosome helps form a peptide bond between 1st and 2nd amino acid
Bond between tRNA molecule and amino acid is broken
tRNA shifts to 3rd site.

14. Ribosome moves over one codon
New tRNA enters ribosome
Process repeats itself.

15. Translation continues until a stop codon
Ribosome release polypeptide and mRNA.

16. Molecular Basis of Heredity
Most genes contain instructions for assembling proteins.

17. Proteins Can Be enzymes Produce pigment or odor Regulate growth
Trigger development
Operate cell parts.

18. Gene Expression What DNA actually ends up doing
How the genes gets expressed or shown.

19. Genetic code is nearly universal in all living organisms.

20. A certain gene has the following base sequence GACAAGTCCACAATC
Write this sequence down
From left to right, write the sequence of mRNA molecule transcribed from this gene
Using the figure on pg. 311, read the mRNA from left to right and write down the amino acid sequence
Repeat step 3 reading the codons from right to left.

21. Analyze and Conclude
Apply Concepts Why did steps 3 and 4 produce different polypeptides
Infer Do cells usually decode nucleotides in one direction only or in either direction