Homework 2 is due 1017 Bonus 1 is

• Homework #2 is due 10/17 • Bonus #1 is due 10/24 Office hours: M 10/8 10 -11: 30 am 2 -5 pm in Bio 6

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

m. RNA transport is an important regulatory step Molecular Biology of the Cell 4 th ed. Alberts et al. Fig 6. 40

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

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

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

Seeds germinated underground begin growing in darkness then emerge into light and begin photosynthesis energy from seed energy from sun

The level of this m. RNA increases after plants are exposed to light. • How might the cell accomplish this?

The level of this m. RNA increases after plants are exposed to light. • How might the cell accomplish this? Increased transcription and/or decreased m. RNA degradation

Northern blot analysis: The level of this m. RNA increases after plants are exposed to light. • How might the cell accomplish this? • Does this necessarily lead to increased protein production?

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

C. elegans is commonly used to study development

C. elegans development

C. elegans mutants with cells that do not develop properly. Fig 12. 25 and

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? 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 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

Silencing RNAs (si. RNA) are artificially induced ds. RNA Fig 8. 22

si. RNA with exact matches to the target m. RNA causes degradation of the m. RNA Fig 8. 21

micro. RNA Translation inhibited si. RNA m. RNA degraded

Fig 8. 19

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

• Homework #2 is due 10/17 • Bonus #1 is due 10/24 Office hours: M 10/8 10 -11: 30 am 2 -5 pm in Bio 6