Flashcards in Genes and Chromosomes (Part 2) Deck (16):
What are the functions of the 7-Me G - 5’ mRNA Cap?
1)•Regulates export of mRNA out of the nucleus:
2)•Required for the efficient translation of the mRNA into protein
3)•CAP and the CAP binding proteins slows 5' degradation of the mRNA.
Mature mRNA is exported in ____ that contain a _____ at the ___ along the rest of the sequence
Cap Binding Complex (CBC)
5’ end & RNA binding proteins
The cap binding complex on the mRNA facilitates recognition by what?
Translation initiation machinery
How does CAP and the CAP binding proteins slows 5' degradation of the mRNA?
By blockage of de-capping enzymes to the cap
-this increases the t1⁄2 of the mRNA
What are the Functions of 3’ mRNA Polyadenylation?
-Poly-A tail Increases the t1⁄2 of the mRNA by protecting it from enzymatic degradation in the cytoplasm
-PABP interacts with stuff at the 7-Me-G CAP
The 5’ splice donor sequence always possesses a ___ sequence & the 3’ splice acceptor always an ___ sequence
Lariat structure forms as the __ splice donor links to the invariant__ within the intron
What allows for a corresponding number of different proteins to be produced from the same gene?
Alternative variations in splicing
Editing of apolipoprotein-B mRNA:
In human liver, unedited mRNA is translated to yield a 4536-amino-acid protein called ____. In human intestine, however, the mRNA is edited by a base modification that changes a specific ___. This modification changes the codon for ____ to a ___, resulting in synthesis of _____.
-C to a U
-termination codon (UAA)
-a shorter protein (Apo-B48, consisting of only 2152 amino acids).
What type of RNA does RNA Polymerase 1 transcribe in eukaryotes?
1) RNA pol I: rRNA genes (nucleoli)
-Most abundant RNA in cells
-Protein synthesis machinery
What type of RNA does RNA Polymerase II transcribe in eukaryotes?
mRNA from all protein-coding genes & some snRNAs.
What is inhibited by α-amanatin (poison deathcap mushroom)?
RNA Polymerase II
What type of RNA is transcribed by RNA Polymerase III?
RNA pol III: tRNA genes & some snRNAs
-2nd most abundant RNA species in cells
-tRNA is the adaptor molecule between NA and peptide
What are enhancers and what is its role?
Cis acting DNA sequences (on the same chromosome) that enhance the rate of transcription by RNA Polymerase II.
What type of transcription factors do enhancers bind to?