1. RNA and Protein Synthesis Chapter 13 (M)

2. Information Flow Language of DNA is written as a sequence of bases If the bases are the letters the genes are the sentences Information in DNA is made into Protein RNA  carries & translates the message in DNA to protein DNA  RNA  Protein

3. Flow of information :

4. The “Central Dogma” proteinRNADNA transcriptiontranslation replication How do we move information from DNA to proteins?

5. Types of Nucleic Acid DNA (Deoxyribonucleic Acid) - transmits genetic information that is passed from one generation to the next- double helix RNA (Ribonucleic Acid)

6. Nucleotide Composed of  a nitrogen base  a pentose sugar  a phosphate group

7. Structure of DNA & RNA DNA  double strands (a) 5 carbon sugar - deoxyribose (b) phosphate group (c) nitrogenous base – adenine (A), guanine (G), thymine (T), cytosine (C) A=T, G=C RNA  single strand (a) 5 carbon sugar - ribose (b) phosphate group (c) nitrogenous bases - adenine (A), guanine (G), uracil (U),cytosine (C) A=U, G=C

8. RNA-Ribonucleic Acid Single stranded Ribose sugar Four bases  Adenine, Guanine, Cytosine & Uracil(U) Uracil similar to Thymine and pairs with Adenine

9. Types of RNA 1. m RNA  transfers the genetic code of DNA in the nucleus to the ribosome in the cytoplasm 2. t-RNA  transfers amino acids to the ribosome to make proteins 3. r- RNA  ribosomal RNA

10. Transcription: DNA  RNA Construction of RNA along portions of the DNA molecule Stages  Initiation  Elongation  Termination

11. Initiation DNA is double stranded and has regions on it “Promoters” (TATA box) where transcription starts. 1. DNA is unzipped, bases are exposed 2. “RNA Polymerase” attaches to the promoter region ready to start making RNA

12. Elongation 1. RNA nucleotides pair with the exposed DNA bases 2. RNA Polymerase then links the RNA nucleotides together to form a chain (mRNA) 3. As the RNA peels off the DNA chain, DNA strands rejoins.

13. Termination When the RNA Polymerase reaches a special base sequence of DNA (terminator) which signals the end, the RNA Polymerase detaches from the DNA Two other types of RNA – tRNA & rRNA are made in the same way

15. Editing the RNA Message RNA transcribed in the nucleus is modified before it leaves the nucleus as mRNA to be translated. mRNA   Introns  noncoding regions  Exons  the parts that remain & will be translated, or "expressed RNA Splicing  joining of the exons after the introns are removed

16. RNA Splicing

17. Ribosomes and Protein Synthesis 13.2

18. The Triplet Code DNA stores information to make protein  20 AAs, functional if order is correct English  1000s words  arrangement of 26 letters DNA Code  sequence of 3 bases (A,T,G,C)  genetic alphabet Start Codon = 1, Stop Codons =3

19. The Triplet Code

21. Translation Process by which mRNA code is read and converted into a specific amino acid sequence (protein) Players: 1. Ribosomes 2. mRNA 3. tRNA

22. Ribosomes Made of two subunits  Large  p-site,& A-site  Small  m RNA binding site

23. t-RNA

24. Steps in Translation 1. Initiation 2. Elongation 3. Termination

25. Initiation mRNA binds to small subunit of ribosome Initiator tRNA binds to specific start codon on mRNA & carries the AA Met Anticodon=UAC(tRNA) Codon =AUG (mRNA ) Large subunit binds to the small  functional ribosome

26. Initiation

28. Elongation Codon Recognition: incoming tRNA with an AA attached pairs with the mRNA codon on the “A-site” Peptide bond formation: a bond is formed between the AA or peptide on “P-site” & AA on the “A-site” Translocation: “P-site” tRNA moves out. “A-site” tRNA w/polypeptide chain moves to “P-site”

29. Ribosome with mRNA and tRNA

30. Figure 17.18 The elongation cycle of translation

31. Termination Process continues till a “stop codon” is reached Process is terminated. Stop Codons: UAA, UAG, UGA

32. Termination

33. Mutations in Genes Ch 13.3

34. Mutation A change in the nucleotide sequence of DNA Can involve large sections of the DNA or just a single nucleotide pair (Point mutations) Types  Base Substitution  Base Deletion  Base Insertion

35. Base Substitution

37. Base Insertion/Deletion Is usually more disastrous than the effects of base substitutions RNA is read as a series of triplets, thus adding or removing nucleotides will affect all nucleotides downstream. Will result in a different, non working protein

39. Causes of Mutations May occur when errors are made during DNA replication When errors are made during chromosome crossovers in meiosis. Physical or chemical agents  mutagens

40. Mutagen Physical mutagen  high-energy radiation  X-rays and ultraviolet light. Chemical mutagen  chemicals that are similar to normal DNA bases but cause incorrect base-pairing when incorporated into DNA.

41. Mutations: Good or Bad Harmful Cancers Sickle cell disease Beneficial Chemical resistance Plants  polyploidy

42. Mutations: Good or Bad Mutations  genetic diversity May be beneficial  tiger swallowtail butterfly  mutations cause a change in color  predators confuse it with w/ black swallowtail which is poisonous and avoid it