KAL - Transcriptional Control in Eukaryotes Flashcards
Why is transcriptional control in eukaryotes much more complex? (3)
- Genes have to respond to environmental conditions
- Genes are under developmental control
- Genes have to be switched on in the correct tissues
How is mature mRNA produced?
Non-coding introns are spliced out and exons are joined together
Describe the structure of the eukaryotic promoter
TATA box at -30
How is eukaryotic transcription controlled? (2)
1. Transcriptional regulators
2. Epigenetic processes
What are the 3 types of transcriptional activators?
- Transcriptional activators that confer general expression
- Transcriptional activators that confer tissue specific expression
- Transcriptional activators that confer response to particular stimuli
How does growth hormone deficiency occur?
Mutations in transcriptional activators
What does the term epigenetics mean?
Processes that induced long-term stable changes in gene activity without a change in gene sequence
What are the 2 major epigenetic processes?
- Histone modification
- DNA methylation
Is DNA tightly packed with histones transcriptionally active?
No
What are the 2 main domains of histones?
1) Globular domain
2) Amino tail domain
How does histone modification work?
Acetylation of the lysines in the tail neutralises their charge
- Opens up the DNA
How does histone modifciation increase gene activity?
No longer tightly packed and genes are more accessible to transcription factors and RNA polymerase
What are epignetic writers?
Enzymes that add epigenetic groups to DNA/Histones
- e.g Histone acetyltransferases (HATs)
What are epigenetic erasers
Enzymes that remove epigenetic groups from DNA/Histones
- e.g Histone deacetylases (HDACs)
What is DNA methylation?
Addition of a methyl group to DNA
