Question

Which type of transcriptional termination requires formation of a stem loop secondary structure in the RNA?

What is the primary factor involved in the termination of RNA synthesis?

Is a new nucleotide added to a growing strand of RNA at the 3′ end?

DNA and associated histones compose what molecule?

Be able to use a codon table to give the sequence of amino acids from an mRNA sequence. I will give you an mRNA sequence; you will indicate how many amino acids are encoded in the polypeptide.

What mutation causes no detectable change in the function of the protein?

What mutation changes a codon from one amino acid to another?

What mutation causes a change in a single base pair?

What happens when you remove the 5' G-cap of mRNA transcripts in eukaryotes?

What are general mechanisms of mRNA regulation (can be achieved at the level of)? What is heterochromatin and euchromatin?

What are these forms associated with?

Do transcriptionally active genes show lower levels of DNA methylation compared with transcriptionally inactive genes?

What do Spliceosomes do?

In eukaryotes, precursor mRNA molecules are processed in the…

Answer 1

1)Most rho independent terminators have two features :   

1. A region that produces an RNA transcript with GC rich self complementary sequences permitting the formation of a hairpin (stem-loop) structure centered 15-20 nts before the projected end of the RNA strand.   

2. Highly conserved string of three A residues in the template strand that are transcribed to U residues near the 3’end of the hairpin.

The stem-loop structure alters the conformation of RNA-pol, leading to the pause of the RNA-pol moving.

Then the competition of the RNA-RNA hybrid and the DNA-DNA hybrid reduces the DNA-RNA hybrid stability, and causes the transcription complex dissociated. Among all the base pairings, the most unstable one is rU:dA.

spliceosome

Most introns are not self-splicing, and these types are not designated with a group number.

The third and largest class of introns includes those found in nuclear mRNA primary transcripts.

These are called spliceosomal introns because their removal occurs within and is catalyzed by a large protein complex called a spliceosome.