What is the role of transcription factors?Break apart old mRNA polymersInitiate gene expressionControl the modification of proteinsAdd a “cap” and “tail” to mRNA

a.Briefly describe the role of RNA polymerase in gene transcription.

What is a transcription factor or transcription regulator? A protein required for mRNA nuclear export A protein that regulates DNA synthesis A protein that interacts with mRNA and increases translation A protein that binds to the DNA origin of replication A protein that binds to a cis-regulatory DNA sequence and affects the probability of gene transcription

What is the role of transcription factors in gene expression? How might general vs. specific factors function in gene expression?

Translation of mRNA to produce proteins is highly regulated.  For example, one factor that regulates eukaryotic translation is the polyadenylate binding protein (PABP).  PABP upregulates translation by binding the poly-A tail of an mRNA molecule (ie, the 3' end of mRNA consisting of multiple adenosine residues) to help recruit the ribosome.PABP consists of a single polypeptide chain and contains four distinct RNA recognition motifs (RRM's), each of which contains four β-strands and two α-helices.  Mutation experiments revealed that each RRM binds poly-A tails through residues in several β-strands.  Crystallography showed that the two α-helices in each RRM, which consist of amino acids 9-24 and 52-60, respectively, help hold the β-strands in the correct orientation for RNA binding.In addition to binding poly-A tails, PABP can also bind to the eukaryotic initiation factor eIF4G through the α-helices in the RRM regions.  When both eIF4G and mRNA with a poly-A tail are present with PABP, a ternary complex between the three molecules can form.  This complex further enhances translation relative to the PABP-mRNA complex alone.  To better characterize these binding interactions, PABP was electrophoresed in a native gel in the presence of mRNA containing a poly-A tail.  When eIF4G was added, PABP affinity for poly-A tails increased 10-fold.  Additional observations revealed that the affinity of PABP for eIF4G increased 12-fold when mRNA with a poly-A tail was added. Question 55Each of the following amino acid residues is likely to be found in the portion of the RRM that binds eIF4G EXCEPT:A.LeucineB.ArginineC.GlycineD.Serine

Which of the following events occurs during transcription?View Available Hint(s)for Part AThe message in mRNA is translated into a protein.Those segments of the RNA strand that do not actually code for the protein are removed.A molecule of RNA is formed based on the sequence of nucleotides in DNA.A cap is added to the RNA molecule.mRNA binds to a ribosome in the cytoplasm.