1. 10/19/2015 1 Genes and How They Work Computer Filename: genes2.ppt Hugh B. Fackrell

2. 10/19/2015 2 Overview Genes composed of DNA within the chromosome Genes code for proteins DNA is transcribed into RNA RNA is translated into Protein by ribosomes Genes regulated by control of RNA production

3. 10/19/2015 3 CODONS sequences of three adjacent nucleotides that code for one amino acid or polypeptide termination 64 codons encrypt of ~ 20 amino acids degenerate RNA: ACU, ACC,ACA, ACG threonine degenerate DNA: TGA, TGG,TGT, TGC threonine

4. 10/19/2015 4 Start Codon RNA: AUG DNA: TAC also codes for methionine

5. 10/19/2015 5 Stop Codon Nonsense Codons RNA: UAA,UAG,UGA DNA: ATT, ATC, ACT

6. 10/19/2015 6 Structure of the Genetic Code DNA : sequences of four nucleotides A,T,G,C CODONS : blueprint for the polypeptide Start & Stop Signals: Where to read the blueprint Regulatory Sequences: When to read the blueprint : operators, enhancers, promotors

7. 10/19/2015 7 Interpreting the Genetic Code Two step process : –Transcription DNA --> RNA –Translation RNA--> protein

8. 10/19/2015 8 Operon A cluster of functionally related genes and regulator sites transcribed onto single mRNA common in prokaryotes and fungi

9. 10/19/2015 9 Transcription occurs in nucleus DNA unravels- single strand RNA Polymerase binds to Promotor site Reads from start sequence(ATG) assembles complementary single strand of RNA (primary RNA) Disengages when reaches stop codon Production of an RNA copy of the gene

10. 10/19/2015 10 Transcription Regulation Controlled by DNA Binding proteins that bind to specific nucleotide sequences some bind in the groove of DNA helix some bind to single stranded DNA Promotor site Activator site (positive regulation) Operator site (negative regulation) Enhancer site

11. 10/19/2015 11 Promotor Site Controls when DNA transcribed Called TATA box Sequence TTGACA or TATAAT (‘sense’) complementary sequences are AACTGT and ATATTA(‘antisense’) Start codon 30 BP downstream

12. 10/19/2015 12 DNA Binding Proteins Negative control :Blocks transcription of DNA to mRNA Postive control: Initiates transcription of DNA to mRNA

13. 10/19/2015 13 Negative Control Process is called Repression Process is controlled by a protein called a Repressor Repressor protein has two configurations

14. 10/19/2015 14 Operator site sequence of nucleotides between the promotor and the gene binding site for the repressor protein blocks RNA polymerase from reading the gene

15. 10/19/2015 15 Tryptophan Repressor: Gene off

16. 10/19/2015 16 Tryptophan repressor : gene ON

17. 10/19/2015 17 Positive Control process called activation process controlled by a protein called Activator

18. 10/19/2015 18 CAP Protein Positive regulator Binds to Outside of DNA Alternative to glucose metabolism Glucose decrease increases CAMP CAMP binds to CAP CAP binds to DNA

19. 10/19/2015 19 Gene Regulation (1/6)

20. 10/19/2015 20 Gene Regulation (2/6)

21. 10/19/2015 21 Gene Regulation (3/6)

22. 10/19/2015 22 Gene Regulation (4/6)

23. 10/19/2015 23 Gene Regulation (5/6)

24. 10/19/2015 24 Gene Regulation (6/6)

25. 10/19/2015 25 Question Design a gene regulation system that has an activator that is turned OFF in the presence of a substrate and a promotor that is turned ON in the presence of a product. Define a series of gene regulators that would turn a ‘cascade’ on and then off in series Define, promotor, activator and operator repressor, enhancer