L16: Splicing, Gene Structure, Translation Flashcards
1
Q
What is alternative splicing and what does it do?
A
- IT is different splicing patterns and this creates splice variants.
2
Q
What are splice variants?
A
- More than one type of protein can be made from a single gene coding for an mRNA.
3
Q
Describe DNA packaging in bacteria.
A
- Promoters are unpackaged, hence accessible to RNA polymerase.
- “Default” state is always on
4
Q
Describe DNA packaging in eukaryotes.
A
- DNA is packaged tightly and must be un-packaged (decondensed) for the RNA polymerase to access the DNA and start transcription.
5
Q
What does Eukaryotic RNA processing involve?
A
- CAP
- polyA
- Splicing
6
Q
What does the term “mature” or “final” RNA transcript refer to?
A
- the RNA molecule has been processed and ready to be exported from the nucleus.
7
Q
Describe the 5’ cap and polyA tail.
A
- Increases the stability of the mature RNA and protects from degradation
- Helps regulate its translation; more proteins are produced from mRNAs with caps and tails
- Helps the final, mature mRNA transcript leave the nucleus through a nuclear membrane transport protein
8
Q
What are introns?
A
- long non-coding sequences that interrupt the coding region of eukaryotic mRNA
9
Q
What are exons?
A
- sequences that code for amino acids
10
Q
What does the coding region begin and end with?
A
- usually exons!
- introns are located between the exons
- 5’ and 3’ untranslated regions are non-coding regions
11
Q
What is RNA splicing?
A
- Introns are removed (spliced) from the mRNA transcript
- Exons can be kept or removed
12
Q
Where does splicing occur?
A
- In the nucleus
13
Q
What are splice junctions?
A
- Sequences between exons and introns that are cut sites
14
Q
Are mRNAs always spliced in the same manner?
A
- Depends on the cell
- Different splicing patterns are called alternative splicing or creating splice variants
15
Q
Is the triplet code universal?
A
- It is
- All organisms use this code to translate
