During transcription, RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure, what is it’s DNA-binding sequence?
TTAA
AATT
CACC
CACC
D.
CACC
TATA box is present in eukaryotic promotor region. It has a resemblance with pribnow box of prokaryotes. TATA box was identified by Dr. Hogness and so, it is called as Hogness box. It is a 7 bp long region located 20 bp upstream to the start point. During the process of transcription the RNA polymerase (a holoenzyme which has a core unit and sigma factor for proper initiation of transcription) binds to TATA box due to which DNA assumes a saddle-like structure at this place.
Telomere repetitive DNA sequences control the function of eukaryotic chromosomes because they
act as replicons.
are RNA transcription initiator
help chromosome pairing
help chromosome pairing
D.
help chromosome pairing
Telomeres are ends of a chromosome, have repetitive DNA sequences and are stable and resistant to exonuclease digestion hence, essential for chromosome stability.
Differentiation of organs and tissues in a developing organism, is associated with
developmental mutations
differential expression of genes
lethal mutations
lethal mutations
B.
differential expression of genes
Differentiation of organs and tissues in a developing organism, is associated with differential expression of genes. In regulation of gene expression the chromosomal proteins play an important role. The chromosomal proteins are of two types histones and non-histones. The regulation of gene expression involves an interaction between histones and non-histones.
The linking of antibiotic resistance gene with the plasmid vector became possible with
DNA ligase
endonucleases
DNA polymerase
DNA polymerase
A.
DNA ligase
DNA ligase is used to seal the nicks that remain in recombinant DNA molecule. In fact, DNA ligase joins together the neighbouring nucleotides flanking a discontinuity in a DNA strand by forming a phosphodiester bond. A recombinant DNA molecules is a vector into which the desired DNA fragment has been inserted to enable its cloning in an appropriate host.
Endonucleases are the enzymes that produce internal cuts called cleavage in DNA molecules. A class of endonucleases cleaves DNA only within or near those sites, which has specific base sequences, such endonucleases are known as restriction endonucleases.
Exonucleases are enzymes that remove one or more nucleotide from the free ends.
DNA polymerase is the enzyme, which causes polymerization of nucleotides during DNA replication.