Chapter 11: Gene Expression Control in Division & Development pp 217-228.
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Transcript of Chapter 11: Gene Expression Control in Division & Development pp 217-228.
![Page 1: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/1.jpg)
Chapter 11: Gene Expression
Control in Division & Developmentpp 217-228
![Page 2: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/2.jpg)
Prokaryotes
• 1965 Nobel Prize to Jacob & Monod for work on lac operon in E. coli
• Lactose is metabolized by 3 enzymes in E. coli• Genes for these proteins are sequential• An operator sits between promoter & these
structural genes• lac operon = promoter + operator + 3 genes• Upstream regulatory gene codes for repressor
![Page 3: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/3.jpg)
lac operon
http://www.phschool.com/science/biology_place/biocoach/lacoperon/regulate.html
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How it works.
• Regulatory gene codes for repressor protein • Repressor protein binds to the operator site• Repressor prevents RNA polymerase
advancement from its promoter site• Repressor protein selectively binds lactose &
cannot bind the operator site then• Repression is lifted genes are “turned on”
only when lactose is present
![Page 5: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/5.jpg)
Eukaryotic control
• Control is at level of individual chromosome• Euchromatin, uncoiled DNA, is site of active
transcription• DNA contains bases that code for proteins
(exons) & bases that do not (introns)• Exons & introns are both transcribed• Only exons are translated• Introns may serve as regulatory elements
![Page 6: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/6.jpg)
Transcriptional Control
• Pre-mRNA is full copy of DNA gene’s message• Splicesomes (RNA + protein) cut out introns &
fuse exons; ribozymes (RNA) also splice• Introns regulate RNA, bind to &/ or control
expression• Exons can code for functional domains• Exons can be selected to form specific protein
![Page 7: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/7.jpg)
Transcriptional Control
• Transcription factors (TF) bind to regulatory elements on DNA, proteins, & other TF– Promoters– Enhancers– Repressors
• TF recruit RNA polymerase to promoter• TF-to-TF binding can change shape of DNA
![Page 8: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/8.jpg)
TF-binding Interactions
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Genes for Development• Cells differentiate to become specialized– Every zygote has all the DNA– Cells/ tissue specialize in morphogenesis– Cells only express DNA for their functions
• Homeotic genes dictate loci of anatomy– Specific sequence within gene = “homeobox”
• Homeotic genes form regulatory proteins– Control which genes are expressed– Control rates of cell division & gene expression
![Page 10: Chapter 11: Gene Expression Control in Division & Development pp 217-228.](https://reader036.fdocuments.net/reader036/viewer/2022082517/56649e265503460f94b15aa4/html5/thumbnails/10.jpg)
Cancer & Cell Control• Proto-oncogenes control normal cell division,
growth, & behavior• Carcinogen = mutagen DNA damage• Mutated proto-oncogenes “oncogene”• Oncogenes promote uncontrolled growth
tumors (benign or malignant) cancer• Metastasis = spread of CA beyond origin• Mutated tumor-suppressor genes cancer– Mutations in all 3 tumor-suppressor genes + viral
oncogene + mutated proto-oncogene
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Types of Cancer• Carcinomas– Skin & tissues lining organs
• Sarcomas– Bone & muscle
• Lymphomas– Lymphatic system’s solid tumors
• Leukemia– Blood-forming tissues uncontrolled WBC production