1. Genes and How They Work Chapter 15

2. 2 The Nature of Genes information flows in one direction: DNA (gene)RNAprotein TranscriptionTranslation

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4. GENE

5. 5 The Genetic Code codon: set of 3 nucleotides(mRNA) that specifies a particular amino acid (64 possible codons) stop codons: (UUA, UGA, UAG) used to terminate translation start codon: (AUG) used to start translation

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7. 7 Gene Expression Overview template strand: used to make RNA coding strand: complementary to the template strand RNA polymerase: puts nucleotides together to make RNA strand

8. 8 Gene Expression Overview types of RNA: messenger RNA (mRNA) carries the info from DNA that encodes proteins ribosomal RNA (rRNA) part of ribosome transfer RNA (tRNA) carries amino acids to the ribosome

9. 9 Transcription Transcription proceeds through: 1.initiation 2.elongation – RNA nucleotides are added to the 3’ end of the new RNA 3.termination

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11. 11 Eukaryotic pre-mRNA Splicing introns – non-coding sequences exons – sequences that will be translated

12. 12 tRNA and Ribosomes The ribosome has two primary functions: –decode the mRNA –form peptide bonds

13. 13 Translation 1.initiation 2.elongation – tRNAs bring amino acids to the ribosome 3.Termination – stop codon

14. 14 tRNA and Ribosomes tRNA –amino acids carried by the acceptor arm –the anticodon loop 3 nucleotides complementary to mRNA codons

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18. 18 Mutation: Altered Genes Too much genetic change (mutation) can be harmful to the individual. However, genetic variation (caused by mutation) is necessary for evolutionary change of the species.

19. 19 Mutation: Altered Genes Point mutations alter a single base. Chromosomal mutations change part of a chromosome (deleted/repeated/moved)

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