At a high concentration of tubulic subunits, translation of tubulin MRNA. a) dec

Question

At a high concentration of tubulic subunits, translation of tubulin MRNA. a) decreases b) increases c) remains unchanged Methylation of DNa gene expression. a) increases b) decreases c) does not change Human gene therapy in the treatment of severe combined immunodeficiency (SCID) did NOT involve: a) use of a modified retrovirus as vector b) Injecting the virus carrying the ADA gene directly into the patient c) use of tissue culture Enhancer elements: a) can be located downstream from the promoter b) function in only one orientation c) are located within 200 bp from the TATA box d) are the same as a CC box Which of the following is true? a) Silencers are proteins that bind to enhancer DNA sequences. b) Activators are proteins that bind to enhancer DNA sequences. c) Enhancers are proteins that bind to activator DNA sequences d) A repressor is a DNA sequence, NOT a protein. A promoter a cis-acting site. a) is b) is not If a wild type E. coli strain is grown in the presence of lactose, the operon will be: a) transcribed b) NOT transcribed In the lactose operon of E. coli lac o is the operator genelac i is the repressor gene and lac z codes for beta-galactosidase. If an E. coli strain of genotype lac o^cz^/F'o is grown in the absence of lactose, the lac z gene will be: a) transcribed b) NOT transcribed In the lactose operon of E. coli lac o is the operator gene, lac i is the repressor gene and lac z codes for beta-galactosidase. If an E. coli strain of genotype lac i^-z^+/F'i^+ is grown in the absence of lactose, the lac z gene will be: a) transcribed b) NOT transcribed In positive regulation, an operon is transcribed when the regulatory protein is bound to the DNa. a) more b) less

Explanation / Answer

9. The regulation of tubulin synthesis is an auto-regulatory process. The abundance of tubulin pools determines the production rate of tubulin molecules which forms the microtubules. Hence, at the higher concentration of tubulin subunits translation of tubulin mRNA decreases. Option (a) is the correct answer.

10. Gene expression requires the unwinding of DNA so that it can be transcribed into mRNA. Methylation is a process of adding methyl groups on cytosine and adenine in the DNA. It is an epigenetic mechanism used to lock the DNA in the coiled form and not allow it to unwind for transcription. It puts the methylated gene into an “off” state. Hence, Methylation of DNA decreases gene expression. The correct answer is (b).

11. Use of gene therapy in the treatment of SCID was first used in 1990 on a four year old Ashanti desilva. Gene therapy of Ashanti was the first successful attempt. Some of her white cells were collected from blood. These cells were injected with a healthy adenosine deaminase gene (ADA) inserted into a retrovirus. The cells were not cultured and they were injected back into her body. Then cells started to express ADA normally. Hence, option (c) is the correct answer. There was no use of tissue culture in the gene therapy of SCID treatment.

12. Enhancers are short regions on DNA where activator proteins can bind to increase the transcriptional rate of a gene. They can be located upto 1000000bp away from the gene or can be upstream or downstream to the gene. They can function in any direction, backward or forward. GC box is a set of nucleotides found upstream to TATA box and sometimes, acts like enhancer. Hence, the answer is enhancer elements are the same as GC box. Option (d) is the correct answer.

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