Question

18. Which of the following statements correctly describe the role of transcription in the initiation of transcription in eukaryotes? A. Some transcription factors must bind to the promoter before RNA polymerası bind. B. Some transcription factors must bind to the promotor proximal element to en significant levels of mRNA production C. Some transcription factors can bind to enhancer elements thousands of base away from the gene D. Some transcription factors can bind to silencer elements that might be locate thousands of base pairs away from a gene to reduce mRNA transcription E. all of the above 19. Which of the following areas does a mature eukaryotic mRNA molecule lach A. 5 untranslated region B. 5' cap C. 3'untranslated region D. polyA tail E. introns 20. 15. The spliceosome is located A. in the mitochondria B. in the nucleus C. in the ribosome D. in the cytoplasm E. in the plasma membrane 21. In the lac operon, the inducer A. binds to the operator region B. binds lactose C. binds RNA polymerase D. binds to the repressor protein E binds a promotor 22. How much of the human genome is thought to be used to make proteins? A. 1 % B. 3% C. 23% D. 76% E allofit is believed to be translated

Answer 1

Ans 18- e- all of the above

In eukaryotic cells, there are two types of transcription factors specific transcription factors and General transcription factors, which regulated the transcription of the gene. Transcription factors can bind with the DNA sequence and regulate the binding of the RNA polymerase, they can either activate the gene by binding to the enhancer sequence or repress the gene expression by binding to the silencer elements. Assembly of the general TF takes place before the binding of the RNA polymerase. Specific transcription factors are required for the formation of the preinitiation complex.

Ans 19- e - introns

Introns are removed during splicing of the pre mRNA and exons are ligated together to form the mature mRNA thus the introns are absent in the mature mRNA.

Ans 20 b- in the nucleus

Transcription of the genes takes place in the nucleus where pre mRNA formed and processed into mature mRNA. The spliceosome is required for the splicing of the pre mRNA in which the introns are removed. So the spliceosome is present in the nucleus.

Ans 21 d- binds to the repressor protein

In the lac operon, the inducer is allolactose which can bind with the repressor and leads to a conformational change in the repressor. In the presence of allolactose, the repressor can not bind with the operator and transcription of the lac operon genes takes place.

Ans 22 a- only 1% of the human genome codes for the protein and 99% DNA is noncoding DNA.