The document summarizes the process of gene expression from DNA to protein. It discusses how genes provide the code for proteins, the central dogma of DNA to RNA to protein, the types and roles of RNA including mRNA, tRNA and rRNA. It then explains the steps of transcription, processing of mRNA, translation, the genetic code and the role of transfer RNA and ribosomes in protein synthesis.

1. Gene Activity: How Genes Work Mader: Biology 8 th Ed.

2. Outline Function of Genes One Gene-One Enzyme Hypothesis Genetic Code Transcription Processing Messenger RNA Translation Transfer RNA Ribosomal RNA Mader: Biology 8 th Ed.

3. Function of Genes Genes Specify a Polypeptide The one gene-one enzyme hypothesis suggests a genetic mutation causes a change in the structure of a protein. A gene is a segment of DNA that specifies the sequence of amino acids in a polypeptide of a protein. Mader: Biology 8 th Ed.

4. From DNA to RNA to Protein Central Dogma of Molecular Biology: Genes code for the sequence of nucleotides in RNA molecules. RNA brings about formation of a protein coded for by DNA of a particular gene. Mader: Biology 8 th Ed. Transcription DNA Replication mRNA Translation PROTEIN Nucleus Cytoplasm

5. DNA Replication Mader: Biology 8 th Ed.

6. RNA Uracil (U) replaces thymine (T) of DNA. Types of RNA Messenger (mRNA) - Takes message from DNA in nucleus to ribosomes in cytoplasm. Transfer (tRNA) - Transfers amino acids to ribosomes. Ribosomal (rRNA) - Help make up ribosomes. Mader: Biology 8 th Ed.

7. Structure of RNA Mader: Biology 8 th Ed.

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9. Steps of Gene Expression During transcription , DNA serves as a template for RNA formation. During translation , an mRNA transcript directs the sequence of amino acids in a polypeptide. Mader: Biology 8 th Ed.

10. Gene Expression Mader: Biology 8 th Ed.

11. The Genetic Code There is a genetic code for each of the 20 amino acids found in proteins. Genetic code is a triplet code , with each codon consisting of three nucleotide bases. Code Properties Universal Degenerate Unambiguous Contains start and stop signals Mader: Biology 8 th Ed.

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13. Transcription During transcription, an mRNA molecule is formed with a sequence of bases complementary to a portion of one DNA strand. RNA polymerase joins the nucleotides together in 5’  3’ direction. Promoter defines start of a gene, the direction of transcription, and the strand to be transcribed. Elongation continues until polymerase comes to a DNA terminator sequence. Mader: Biology 8 th Ed.

14. Transcription Mader: Biology 8 th Ed.

15. Processing Messenger RNA Newly formed mRNA molecule, primary mRNA transcript, is modified before it leaves the eukaryotic nucleus. Cap on 5’ end, and poly-A tail on 3’ end. Introns are removed during RNA processing, leaving only exons . Mature mRNA In most cases, mRNA splicing is done by a spliceosome. Mader: Biology 8 th Ed.

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17. Translation Transfer RNA molecules transfer amino acids to the ribosomes. tRNA molecules bind with one particular amino acid, and bear an anticodon complementary to the codon for that amino acid. tRNA synthetases attach correct amino acid to the correct tRNA molecule. Mader: Biology 8 th Ed.

18. Transfer RNA Mader: Biology 8 th Ed.

19. Role of Ribosomal RNA Ribosomal RNA (rRNA) is produced off a DNA template in the nucleolus of a nucleus. Packaged with proteins into ribosomal subunits, one larger than the other. Contain binding sites to facilitate complementary base pairing between tRNA anticodons and mRNA codons. Mader: Biology 8 th Ed.

20. Ribosomes consist of two subunits. The large subunit has three binding sites for tRNA. The small subunit binds to mRNA.

21. Ribosome Structure and Function Mader: Biology 8 th Ed.

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23. A. Initiation Mader: Biology 8 th Ed.

24. B. Elongation Mader: Biology 8 th Ed.

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26. C. Termination Mader: Biology 8 th Ed.

27. Online Activities and Tutorials Mader: Biology 8 th Ed. http://learn.genetics.utah.edu/content/begin/dna/transcribe/ http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120077/micro06.swf::Protein%20Synthesis http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter3/animation__mrna_synthesis__transcription___quiz_1_.html http://www.phschool.com/science/biology_place/biocoach/transcription/tcproc.html http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter3/animation__mrna_synthesis__transcription___quiz_2_.html