16. Transcription

Question 1

synthesis of RNA using DNA as a template

Answer 1

transcription

Question 2

DNA promoter sequence in prokaryotes

Answer 2

• -35 sequence (TTGACA)

* Pribnow box (TATAAT) -10 bp

Question 3

DNA promoter sequence in eukaryotes

Answer 3

• TATA or Hogness box , -25 bp

* CAAT box, -70to 80 bp

Question 4

Steps in transcription

Answer 4

1. Initiation
2. elongation
3. termination

Question 5

local unwinding of DNA continues in this direction

Answer 5

5’ to 3’ direction

Question 6

used to synthesize rRNA

Answer 6

RNA polymerase Pol I

Question 7

used to synthesize mRNA, IncRNA, miRNA, SnRNA

Answer 7

RNA polymerase Pol II

Question 8

used to synthesize tRNA, 5SrRNA

Answer 8

RNA polymerase Pol III

Question 9

what are post transcriptional modifications

Answer 9

• introns removed
• exons are spliced together
• RNAs are extensively modified
  
  • addition of 7-methylguanosine cap
  • addition of poly (A) tail
  • addition of CCA tail
  • methylation, reduction, deamination and rearrangement of glycosidic bonds to create unusual bases

Question 10

part of the bacterial chromosome that controls the synthesis of enzymes involved in lactose metabolism

Answer 10

lactose operon

Question 11

this bacterial gene encodes for ß-galactosidase

Answer 11

Z gene

Question 12

this bacterial gene encodes for galactosidase permease

Answer 12

Y gene

Question 13

a transport protein required for entry of lactose into the cell

Answer 13

galactosidase permease

Question 14

this bacterial gene encodes for thiogalactoside transacetylase

Answer 14

A gene

Question 15

this bacterial gene encodes for lac repressor protein , located at distant site in DNA

Answer 15

I gene

Question 16

Full expression of the lactose operon requires

Answer 16

1. repressor protein must not bind to the operator
   •lactose must be present to prevent repressor binding
2. cAMP dependent activator protein must bind to CAP site
   •glucose must be low to allow cAMP to inc