Which one of the following makes use of RNA as a template to synthesize DNA?
Reverse transcriptase
DNA dependant RNA polymerase
DNA polymerase
RNA polymerase
During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called?
CAAT box
GGTT box
AAAT box
TATA box
Which one of the following hydrolysis internal phosphodiester bonds in a polynucleotide chain?
Lipase
Exonuclease
Endonuclease
Protease
C.
Endonuclease
DNase (or deoxyribonuclease) or simply nuclease is an enzyme which breaks down DNA by hydrolysis of the phosphodiester bonds of its sugar-phosphate back-bone. Depending on the position of hydrolysing phosphodiester bonds, nucleases are of two types:
(i) Endonucleases- It hydrolyses internal phosphodiester bonds in a polynucleotide chain.
(ii)Exonucleases- It hydrolyses terminal phosphodiester bonds in a polynucleotide chain.
E. coli cells with a mutated Z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because
in the presence of glucose, E. coli cells do not utilize lactose
they cannot transport lactose from the medium into the cell
the lac operon is constitutevely active in these cells
they cannot synthesize functional - galactosidase
DNA replication generally proceeds in a
5 3 direction
3 5 direction
3 3 direction
5 5 direction
DNA polymerase enzyme is required for synthesis of
DNA from RNA
RNA from DNA
DNA from DNA
RNA from RNA