more regulating gene expression Gene Expression is controlled

more regulating gene expression

Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15. 1 Fig 16. 1

Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15. 1 Fig 16. 1

Fig 23. 25 Alternate Splicing in Drosophila Sex Determination

Fig 23. 25 Alternate splicing leads to sex determination in fruit flies

m. RNA transport is an important regulatory step Molecular Biology of the Cell 4 th ed. Alberts et al. Fig 6. 40 http: //www. ncbi. nlm. nih. gov/books/bv. fcgi? rid=mboc 4. TOC&depth=2

m. RNA can be localized to a specific parts of a cell (from Drosophila embryo) Molecular Biology of the Cell 4 th ed. Alberts et al. Fig 7. 52 http: //www. ncbi. nlm. nih. gov/books/bv. fcgi? rid=mboc 4. TOC&depth=2

At least 3 mechanisms are involved: Molecular Biology of the Cell 4 th ed. Alberts et al. Fig 7. 98 Directed Random Degradation transport via diffusion and local cytoskeleton and trapping protection

A processed m. RNA ready for translation 5’ untranslated region Protects from degradation/ recognition for ribosome 3’ untranslated region Protects from degradation/ transport to cytoplasm

m. RNA with 3’ UTR properly localized m. RNA without 3’ UTR improperly localized Molecular Biology of the Cell 4 th ed. Alberts et al. Fig 7. 99 http: //www. ncbi. nlm. nih. gov/books/bv. fcgi? rid=mboc 4. TOC&depth=2

Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15. 1 Fig 16. 1

Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15. 1 Fig 16. 1

Fig 15. 25 Regulation of iron assimilation in mammals: Regulating of Translation

Ferritin is regulated at translation Fig 15. 26

C. elegans is commonly used to study development

C. elegans development

C. elegans mutants with cells that do not develop properly.

C. elegans mutants with cells that do not develop properly. The product of these genes was found to be RNA?

Micro. RNAs (mi. RNA) are ~22 nt RNAs that play important regulatory roles Cell vol. 116, 281 -297 2004

mi. RNA expressed How do micro. RNAs control gene expression? Fig 15. 23 and mi. RNA processed to ~22 nt RNA Mature mi. RNA

A processed m. RNA ready for translation: micro. RNAs inhibit translation by binding to the 3’ end of m. RNA micro. RNA bind to 3’-UTR 5’-UTR 3’-UTR

mi. RNA expressed the 3’ end with attached micro. RNA interacts with the 5’ end, blocking translation Fig 15. 23 and mi. RNA processed to ~22 nt RNA Mature mi. RNA

mi. RNAs can lead to methylation of DNA that leads to inhibition of transcription

micro. RNAs primarily target gene products that function during development Tbl 1

tissue specific expression of mouse micro. RNA PNAS vol. 101 #1 pg 360 -365, 2004

Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 16. 1

Phosphorylation and dephosphorylation of proteins can change activity

Ubiquitinization targets proteins for degradation

Some proteins function in the cytoplasm; others need to be transported to various organelles.

How can proteins be delivered to their appropriate destinations?

Fig 13. 23 Proteins are directed to their destinations via signals in the amino acid sequence

Protein Destinations: secretion or membrane

• Signal sequences target proteins for secretion

Translation of secreted proteins

Translation of membrane bound proteins

Translation of secreted or membrane bound proteins This step determines secretion or membrane bound.

Protein Destinations: nucleus Signal anywhere in protein, Translation in cytoplasm, Signal not removed

Protein Destinations: mitochondria or chloroplast Signal translated first, Translation in cytoplasm, Signal removed

Protein Destinations: signals in protein determine destination Tbl 13. 8

Next: Development- differentiating cells to become an organism