Ch 12. Transcription Activators in Eukaryotes Gene-specific transcription factor.
Ch 11 – Gene Expression The control of a gene at transcription, translation for even the...
-
Upload
jessica-francis -
Category
Documents
-
view
225 -
download
0
Transcript of Ch 11 – Gene Expression The control of a gene at transcription, translation for even the...
![Page 1: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/1.jpg)
Ch 11 – Gene Expression
The control of a gene at transcription, translation for even the polypeptide.
![Page 2: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/2.jpg)
Prokaryotes (Bacteria)
Operons – control of transcription
• These comprise of a structural gene, operator and promoter.
• Promoter region organizes RNA polymerase and starts transcription.
• Operator region is binding site for a repressor protein. This protein will stop RNA polymerase from binding.
![Page 3: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/3.jpg)
• Also involved is a regulator gene that codes for that repressor protein.
• These proteins have binding sites for a particular molecule.
• The binding of that molecule will make the repressor protein release from the operator.
![Page 4: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/4.jpg)
• Example from the book (lac operon)
• Repressor protein is attached to operator.
• Lactose will bind to the repressor protein causing it to release from the operator and transcription begins.
• The protein formed is a lactose metabolizing protein.
• It is important to control the production of protein until they are needed. Why?
Energy (ATP)
![Page 5: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/5.jpg)
![Page 6: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/6.jpg)
Eukaryotes use different systems
1. Control of transcription
• In eukaryotic cells, RNA polymerase need transcription factors to attach RNA polymerase to the promoter region on the DNA.
• These factors can “hold” RNA polymerase ready to transcribe a gene.
• “Up stream” of the promoter and structural gene is the enhancer region. Other transcription factors bind here and act as activators.
![Page 7: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/7.jpg)
• When the DNA is bent by bending proteins the transcription factors are brought together and the RNA polymerase is allowed to transcribe the structural gene.
![Page 8: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/8.jpg)
2. Control after translation
• The mRNA (pre-mRNA) is made up of exons and introns.
• Exon (EXpressed) are translated into proteins.
• Introns (INtervening) are removed and not translated.
The introns are removed, the exons assembled together and the new mRNA is translated.
![Page 9: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/9.jpg)
![Page 10: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/10.jpg)
3. Epigenetics
• The control of genes form outside “on top” of the genome.
• Environmental conditions can change the function of your DNA by changing your epigenome (and your offspring).
• Methyl groups can be added to cytosines and adenines turning off the gene. (This could be good or bad)
• Tight coiling of areas of DNA prohibit the promoter region being accessed and thus stopping transcription of the gene. Histones
![Page 11: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/11.jpg)
4. Homeotic Genes
• Regulatory genes that control the pattern of body formation during early development.
• legs, wings, body segments, etc.
![Page 12: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/12.jpg)
![Page 13: Ch 11 – Gene Expression The control of a gene at transcription, translation for even the polypeptide.](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d095503460f949dbf44/html5/thumbnails/13.jpg)
5. Protein Modification
• Modification of proteins
• Insulin