1. Chapter 13 RNA and Protein Synthesis

2. DNA: The Blueprints The structure of DNA “CUT the Pyramids ”

3. DNA: The Blueprints The structure of DNA Double Helix #A = #T #C = #G

4. Central Dogma of Biology DNA- blueprints; instructions mRNA- messenger that delivers the instructions Ribosome- factory that makes proteins tRNA- workers who build the proteins Proteins- ultimate “product” that all life is based on

5. Ribosenucleic Acid (RNA)

6. Transcription In the nucleus, enzymes make Messenger RNA (mRNA) copy of a portion of a DNA strand in a process called transcription. mRNA takes the information from DNA and moves it to the cytoplasm Made be the enzyme RNA polymerase which starts at a promoter (section of DNA)

7. RNA Processing Only in eukaryotic cell mRNA be edited before use Introns- sections to be removed “Introns are in the way” Exons- expressed mRNA

8. What is the mRNA sequence? DNA is always read from 3’  5’

9. The Genetic Code Translation- changing mRNA into an amino acids chain (protein) called a polypeptide A group of three nitrogenous bases in mRNA code for one amino acid. Each group is known as a codon There are 20 Amino Acids How do we know a codon is 3 bases long?

10. Codons How many different DNA bases are there? -4 (A, T, C, G) How many mRNA bases are there? -4 (A, U, C, G) If a codon was only 1 base long how many amino acids could you have? -Only 4 (A= AA #1, U= AA #2, C= AA #3, G = AA #4) If a codon was 2 bases long how many amino acids could you have? -4 2 = 16 (AA, AU, AC, AG, UU, UA, UC, UG, CC,CA, CU, CG, GG, GA, GU, GC) Since there are 20 Amino Acids, a codon must be 3 bases 4 3 =64 Multiple codons mean the same Amino acid

11. Code is degenerate (reused)

12. What is the AA sequence? Codons to remember: Start codon- AUG All proteins start with Methoinine Stop Codons- UAA, UAG, UGA

13. Translation: From mRNA to Protein Translating the mRNA code: 1) Need Ribosomal RNA (rRNA)

14. Translation: From mRNA to Protein 2) Need Transfer RNA (tRNA) -anticodon on tRNA pairs with codons in mRNA

15. Translation: From mRNA to Protein 1) tRNA bring Methionine to A-site 2) Ribosome moves to next condon 3) tRNA brings AA#2 to A-site AA in P-site (Methionine) binds to AA#2 4) Ribosome moves to next codon 5) tRNA brings AA#3 to A-site AA in P-site binds to AA in A-site tRNA in E-site is released 6) Repeat 2-5 until Ribosome hits a stop codon 7) Ribosome releases mRNA and AA chain.

16. Inside prokaryotes transcription and translation happen at the same time. Why is this possible? Prokaryotes have no nucleus

21. Mutations Any change in the DNA sequence is called a mutation. Mutations can be caused by errors in replication, transcription, cell division, or by external agents.

22. Mutations A point mutation is a change in a single base pair in DNA. A point mutation in the base pairs of a codon can change an amino acid A mutation in the 3 rd base is saver than the 1 st. 64 codons and only 20 AA. Extra codons used to protect against mutation

25. Mutations A mutation in which a single base is added to or deleted from DNA is called a frameshift mutation

26. Chromosomal Alterations Structural changes in chromosomes are called chromosomal mutations.

27. Causes of Mutations Any agent that can cause a change in DNA is called a mutagen Radiation ： X rays, cosmic rays, ultraviolet light, and nuclear radiation Chemicals ： dioxins, asbestos, benzene, and formaldehyde High temperatures

30. That’s all