Lecture 9-10 - DNA to Protein Flashcards
What is the central dogma?
DNA is used to make RNA via transcription and RNA is used to make protein through translation.
What are the major differences between RNA and DNA?
- ribose (extra hydroxyl group) instead of deoxyribose
- single stranded
- uracil instead of thymine in base pairing with adenine
- able to form complex 3D structures
- displays some enzymatic activities
The ___________ strand of DNA is used to to create RNA. The ___________ strand of DNA matches the sequence of the RNA created.
Template, nontemplate
What is the name of the enzyme responsible for synthesis of RNA that will be used for translation?
RNA polymerase II
What is required for RNA polymerase to bind to and start translation?
A complex of several proteins which bind to different conserved sequences (ie. TATA box) in the promotor region. These sites can be a few base pairs up stream or several thousand.
RNA polymerase activity creates tension in the DNA causing ___________. If allowed to build up the DNA stand would break so special proteins called ___________ release the tension.
Supercoiling; topoisomerases
Supercoiling in the direction of coiling is ___________ supercoiling and ___________(hinders/facilitates) helix opening.
Supercoiling in the opposite direction of coiling is ___________ supercoiling and ___________(hinders/facilitates) helix opening.
Positive;hinders
Negative;facilitates
In what ways is eukaryotic mRNA processed prior to leaving the nucleus?
- 5’ capping
- RNA splicing
- 3’ polyadenylation
What occurs during 5’ capping and when does it occur?
- 1st nucleotide is dephosphorylated
- GMP is bound 5’ to 5’ to the 1st nucleotide
- guanosine is methylated
This occurs as soon as enough mRNA is sticking out of RNA polymerase, ~ 25 nucleotides
What is RNA splicing?
Removal of introns from mRNA leaving only the exons.
How are intron sequences removed?
Intron junctions and an internal adenine are recognized and bound by a complex of snRNA and proteins. The 5’ end of the pre-mRNA is cut and covalently bound to the internal A (forming a lariat). The 3’ end is cut and intron is removed. Exons ends are bound together.
What is alternative splicing and what is its significance?
Splicing of the same gene in different ways combining different exons to create different versions of the same protein. Because of this one gene can be used to make several different proteins.
Portions of different proteins created by alternative splicing that contain the same exon sequences are called ___________.
Constitutive domains
More complex organisms tend to have ___________ (larger/smaller) introns.
Larger
What is polyadenylation?
The addition of ~200 adenines to the end of a pre-mRNA sequence.
