#Question id: 10397
#Unit 6. System Physiology – Plant
Both VLFRs and LFRs depends on law of reciprocity that is, the magnitude of the response is dependent on the
#Question id: 33103
#Unit 1. Molecules and their Interaction Relevant to Biology
#Question id: 31103
#Unit 2. Cellular Organization
#Question id: 4108
#Unit 3. Fundamental Processes
The yeast Gal4 transcription activator comprises two domains: a DNA binding domain and an activation domain. The DNA-binding domain allows Gal4 to bind to appropriate DNA sequences located near genes that are required for metabolism of the sugar galactose. The activation domain binds to components of the transcriptional machinery (including RNA polymerase), attracting them to the promoter, so the regulated genes can be turned on. In the absence of Gal4, the galactose genes cannot be turned on. When Gal4 is expressed normally, the genes can be maximally activated. When Gal4 is massively overexpressed, however, the galactose genes are turned off. Choose correct explanation for this regulation?
A. In order for Gal4 to work properly, the DNA-bound Gal4 recruits many proteins, including RNA polymerase, to the promoter.
B. When there is too much Gal4 in the cell, the free and DNA-bound Gal4 will compete for the limited quantities of these other components.
C. In the presence of excess Gal4, those components are tied up in unproductive complexes with free Gal4, thereby preventing their recruitment to the promoter.
D. cells that massively overexpress Gal4 grow poorly because of the reduced availability of critical components of the transcription machinery.
E. Over concentration of Gal4 prevent suppressors to bind with DNA
#Question id: 8720
#Unit 9. Diversity of Life Forms
The question refers to the following table, which compares the percent sequence homology of four different parts (two introns and two exons) of a gene that is found in five different eukaryotic species. Each part is numbered to indicate its distance from the promoter (for example, Intron I is the one closest to the promoter). The data reported for species A were obtained by comparing DNA from one member of species A to another member of species A.
Which of these four gene parts should allow the construction of the most accurate phylogenetic tree, assuming that this is the only part of the gene that has acted as a reliable molecular clock?