week 6: gene structure

Question 1

difference between monocistronic and polycistronic gene

Answer 1

mono - has a single protein-coding gene/cistron
poly - multiple cistrons therefore produces multiple proteins

Question 2

explain the central dogma theory. what are its limitations?

Answer 2

a theory that states genetic information flows in only one direction (RNA ->DNA->protein). but this is limited since viruses can do reverse transcription and not all RNA translates to protein (they have regulatory function).

Question 3

what are the steps of transcription?

Answer 3

1.initiation - sigma factors for Pro., TFs for Euk.
2.elongation - promoter/sense strand is coding strand. happens in 5’ to 3’
3. termination - either rho dependent or instrinsic (formation of hairpin loop) in pro. euk.s->poly a tail

Question 4

importance of 5’ capping

Answer 4

addition of a nucleotide at the phosphodiester linkage at the 5’ end. this proteects mRNA from exonuclease attack and is required for translation. helps move mRNA out of nucleus as well.

Question 5

what is splicing?

Answer 5

a process where non conding introns are removed by spliceosome complex of small nuclear ribonucleoproteins (snRNPs).

Question 6

polyadenylation significance

Answer 6

addition of adenines (poly A tail), protects from econuclease attack and helps transport mRNA

Question 7

key difference between ISH and microarray

Answer 7

ISH gives spatial info (what is happening inside the cell) while microarray allows for the analysis of thousands of genes at the same time