THE FLOW OF GENETIC INFORMATION FROM DNA TO RNA TO PROTEIN

1. THE FLOW OF GENETIC INFORMATION FROM DNA TO RNA TO PROTEIN

2. I Can… • Describe the locations, reactants, and products of transcription and translation. • Diagram the overall process of transcription and translation.

3. DNA Proteins  Cells • DNA (genes) has the information to build proteins proteins cells DNA gets all the glory,Proteins do all the work

4. How do proteins do all the work Proteins proteins run living organisms enzymes control all chemical reactions in living organisms structure all living organisms are built out of proteins

5. Protein Synthesis: overview The sequence of DNA determines the sequence of Amino Acids (monomer) that makes up each protein (polymer). • Transcription: synthesis of mRNA under the direction of DNA • Translation: actual synthesis of a polypeptide under the direction of mRNA

6. The Triplet Code • The genetic instructions for a protein/ polypeptide chain are ‘written’ in the DNA as a series of 3-nucleotide ‘words’ called…. • Codons: the basic unit of genetic code • Don’t forget! • ‘U’ (uracil) replaces ‘T’ in RNA

7. Transcription: • Transcription of a gene occurs in three main steps: • Initiation, involving the attachment of RNA polymerase to the promoter and the start of RNA synthesis, • Elongation, as the newly formed mRNA strand grows • Termination, when RNA polymerase reaches the terminator DNA and the polymerase molecule detaches from the newly made mRNA strand and the gene.

8. Transcription: overview

9. 10.10 Eukaryotic RNA is processed before leaving the nucleus as mRNA • Eukaryotic mRNA undergoes processing before leaving the nucleus. • RNA splicing removes introns (intervening sequences) and joins exons (expressed sequences) to produce a continuous coding sequence.

10. Translation • mRNA from nucleus is ‘read’ along its codons by tRNA’s anticodons at the ribosome • Each codon on the mRNA has a complimentary tRNA anticodon (nucleotide triplet) • Each tRNA has been previously linked to an amino acid.

11. Translation continued • Ribosome: site of mRNA codon & tRNA anticodon coupling • P site: holds the tRNA carrying the growing polypeptide chain • A site: holds the tRNA carrying the next amino acid to be added to the chain

13. Translation continued • Initiation:union of mRNA & tRNA • Elongation: • codon recognition • peptide bond formation • Translocation • Termination: • ‘stop’ codon reaches ‘A’ site

14. Translation

15. Figure 10.7-1 DNA A A A C C G G C A A A A Transcription RNA C U G G U U U U U G C U Codon Translation Polypeptide Amino acid

16. Figure 10.8a Second base of RNA codon U C A G U C AG UUU UCU UGU UAU Phe Tyr Cys UGC UAC UUC UCC U Ser UAA Stop UUA UCA UGA Stop Leu Trp UUG UCG UAG Stop UGG U C AG CUU CCU CAU CGU His CGC CUC CCC CAC C Leu Pro Arg CGA CAA CUA CCA Gln First base of RNA codon Third base of RNA codon CGG CUG CCG CAG U C AG AUU AAU AGU ACU Ser Asn AUC lle AAC AGC ACC A Thr AUA AAA AGA ACA Arg Lys AUG AAG Met orstart ACG AGG U C AG GUU GCU GAU GGU Asp GUC GCC GGC GAC G Gly Ala Val GUA GGA GCA GAA Glu GUG GCG GAG GGG

17. Figure 10.8b-1 Strand to be transcribed T A C T T C A A A A T C DNA A T G A A G T T T T A G

18. Figure 10.8b-3 Strand to be transcribed T A C T T C A A A A T C DNA A T G A A G T T T T A G Transcription RNA A U G A A G U U U U A G Startcodon Stopcodon Translation Lys Met Phe Polypeptide

19. 10.8 The genetic code dictates how codons are translated into amino acids • The genetic code is • nearlyuniversal, in that the genetic code is shared by organisms from the simplest bacteria to the most complex plants and animals.

20. Figure 10.15-5 DNA Transcription NUCLEUS mRNA Transcription 1 RNApolymerase CYTOPLASM Translation Amino acid Enzyme Amino acidattachment 2 tRNA ATP Anticodon InitiatortRNA Largeribosomalsubunit Initiation ofpolypeptidesynthesis 3 U C A AUG Start codon Smallribosomalsubunit mRNA New peptidebond forming Growingpolypeptide Elongation 4 Codons mRNA Polypeptide Termination 5 Stop codon

21. Review of Transcription and Translation

22. I Can… • Describe the major types of mutations, causes of mutations, and potential consequences.

23. 10.16 Mutations can affect genes • A mutation is any change in the nucleotide sequence of DNA. • Mutations can involve • large chromosomal regions or • just a single nucleotide pair.

24. 10.16 Mutations within a gene can be divided into two general categories. • Nucleotide substitutions involve the replacement of one nucleotide with another pair of nucleotides. • have no effect at all (silent mutation) • change the amino acid coding (missense mutation) which produces a different amino acid • lead an improved protein that enhances the success of the mutant organism and its descendants, • change an amino acid into a stop codon, (nonsense mutation)

25. 10.16 Mutations can affect genes • Nucleotide insertions or deletions of one or more nucleotides in a gene may • cause a frameshift mutation, which alters the reading frame (triplet grouping) of the genetic message, • lead to significant changes in amino acid sequence, and • produce a nonfunctional polypeptide.

26. 10.16 Mutations can affect genes • Mutagenesis is the production of mutations. • Mutations can be caused • by spontaneous errors that occur during DNA replication or recombination or • by mutagens, which include • high-energy radiation such as X-rays and ultraviolet light and • chemicals.

27. Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders. Beneficial mutations may produce proteins with new or altered activities that can be useful. The larval skate at the bottom has had it’s gene mutated in a lab. This gene in the skate is the same gene in humans that codes for hand shape.