Genes and How They Work

1. Genes and How They Work Chapter 15

2. The Nature of Genes information flows in one direction: DNA (gene) RNA protein Transcription Translation

3. U

4. GENE

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

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

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

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

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

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

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