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TLS Online TPP Program

#Question id: 2897

The transcription of most protein coding genes in mammals (~70 percent) occurs at a lower rate than at TATA box–containing and initiator-containing promoters and begins at any of several alternative start sites within regions of about 100–1000 bp that have an unusually high frequency of CG sequences. Which one of the following best explains it?

#Unit 2. Cellular Organization

  1. CG-rich sequences are bound by histone octamers more tightly than CG-poor sequences because less energy is required to bend around the histone octamer forming a nucleosome.

  2. During housekeeping gene expression, the enzyme methyltransferase is temporarily silenced by miRNA, thus shutting down global methylation.

  3. As soon as the cytosine is methylated in the promoter region, the enzymes of DNA repair pathways remove the methyl group, thereby ensuring gene expression.

  4. A remarkable feature of the CpG islands is that transcription from these elements is initiated in both directions, even though only transcription of the sense strand yields an mRNA.

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TLS Online TPP Program

#Question id: 4890

#Unit 8. Inheritance Biology

A strain of Neurospora crassa, unable to synthesize the vitamin thiamine (t), is crossed with a strain that cannot synthesize the amino acid arginine (a). What information can be obtained from the resultant frequencies of ascospore patterns?

 A) The two loci (a) and (t) are independent assortment of each other

B) Both genes are closely linked to their respective centromeres.

C) no crossovers occurred between either gene and its centromere.

D) These two gene may reside on different chromosomes.
TLS Online TPP Program

#Question id: 34154

#Unit 7. System Physiology – Animal

Which organelle is particularly abundant in adrenal cortex cells due to its role in steroid hormone synthesis?
TLS Online TPP Program

#Question id: 24445

#Unit 13. Methods in Biology

An electrocardiogram is a painless, noninvasive way to help diagnose many common heart problems. Which of the following would not diagnose by ECG?
TLS Online TPP Program

#Question id: 3674

#Unit 3. Fundamental Processes

Which property is shared by E. coli DNA polymerase I and DNA polymerase III?
TLS Online TPP Program

#Question id: 3836

#Unit 3. Fundamental Processes

Which of the following statements accurately describes the differences between DNA replication in prokaryotes and DNA replication in eukaryotes?