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Unformatted text preview: Gene Expression: From Genes to Proteins
Chapter 9 DNA and Protein What is the relationship between DNA and protein? DNA and Protein Each gene makes single protein One gene, one protein In cells: Multiple proteins needed for one job One bad protein breaks the chain Metabolic Pathways Fig. 9.1 Types of RNA Ribosomal RNA (rRNA) = ? Messenger RNA (mRNA) = ? Transfer RNA (tRNA) = ? Ribosomes Fig. 9.9 Transfer RNA (tRNA) Fig. 9.10 Gene Expression Processes Transcription = Translation = Gene Coding Genes are coded in a triplet code These are called..... Each codon codes for an amino acid Genetic Code I love redundancy
The genetic code is: Universal meaning? Degenerate or redundant meaning? Universal Genetic Code
Fig. 9.3 Genetic Code Universal genetic code provides evidence for biological evolution HOW? Flow of Information The Central Dogma of Gene Expression See Fig. 9.5 Transcription
Occurs in the nucleus DNA copied into mRNA Three stages 1. 2. 3. Initiation Elongation Termination Transcription Fig. 9.5 Transcription Animation www.dnai.org Code, copying the code, putting it together, transcription video Transcription: Initiation RNA polymerase binds to promoter region DNA unwinds
Fig. 9.5 Transcription: Elongation Fig. 9.5 Transcription: Termination RNA polymerase reaches the terminator mRNA is released Fig. 9.5 mRNA Modification
In humans, before transcription: mRNA is modified unmodified called pre mRNA Occurs in nucleus Introns and Exons Introns = ? Exons = ? Organization of a Eukaryotic Gene Fig. 9.6 Processing PremRNA Introns are removed Exons are spliced together Cap is added to the 5' end PolyA tail is added to the 3' end Processing PremRNA Fig. 9.7 Translation 1. 1. 1. Occurs at the ribosomes Ribosome reads mRNA tRNA delivers amino acid Polypeptide chains are formed Translation 1. Three steps: Initiation mRNA binds to ribosomes 2. Elongation polypeptide lengthens one amino acid at a time 3. Termination reaches a codon that says `Stop' Translation Figure: 911 Translation Animation www.dnai.org Code, reading the code, putting it together, translation video The Product: Proteins Subunits of proteins are...... 20 of them Amino Acids Are the Subunits of Proteins Fig. 9.8 Protein Function What do proteins do for us? Proteome Proteome = Human Proteome > 100,000 proteins How many genes do we have? How is this possible? Protein Structure Proteins are 3D Function depends on shape Why do we cook? Protein Structure Fig. 9.12 Quaternary Structure of Catalase Fig. 9.14 Prions Prion = EX: Change in 3D shape (folding) of proteins CreutzfeldtJakob Fatal familial insomnia Madcow disease a.k.a Bovine spongiform encephalopathy (BSE) if you want to sound smart Prions Fig. 9.13 Stanley Pruisiner won the Nobel Prize in 1997 for his work with prions and their role in disease ...
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