Chapter 17 Flashcards
Gene expression
Process by which DNA directs protein synthesis
How does RNA’s structure differ from DNA’s?
- Sugar is ribose instead of deoxyribose
- Single stranded
- Uracil instead of Thymine
- Nonhelical
Why must only eukaryotic pre-mRNA go through RNA process?
It must pass through the nuclear envelope
Primary trasnscript
Initial RNA transcript from a gene (pre-mRNA)
What does RNA polymerase do?
- Pries DNA strands apart
- Hooks RNA nucleotides together
What is the stretch of DNA that is transcribed?
Transcription unit
Where does the RNA polymerase attach to to start initiation?
Promoter
What is the TATA box?
Stretch of nucleotides in the promoter region
What do transcription factors do?
Bind to promoter to signal RNA polymerase to come over to the promoter
What signals RNA polymerase to bind to the promoter?
Transcription factors
What does the transcription initiation complex consist of?
RNA polymerase II and transcription factors
How does DNA reallign so quickly after RNA polymerase transcribes the template strand?
Previous RNA stretches peel away
What happens in termination for eukaryotes?
RNA strand is cut from the polymerase that continues to transcribe past the DNA strand
What three things occur in RNA processing?
- Introns are cut away
- 5’ cap is added
- Poly-A tail is added
What are the functions of the 5’ cap and poly-A tail?
- Facilitate export of mRNA
- Protect mRNA from hydrolytic enzymes
- Help ribosomes attach to 5’ end
Introns
Noncoding sequences between coding sequences
What does RNA splicing do?
Removes introns and joins exons
What do spliceosomes consist of?
small sibonucleicproteins (snRNP) and proteins