Researchers investigated whether time of day affects the rate at which certain mRNAs produced by plants are broken down. At either 1 hour after the start of the light period (morning) or 8 hours after the start of the light period (afternoon), the researchers treated identical plant seedlings with a compound that blocks transcription (time = 0 min). The researchers measured the percent remaining of two mRNAs, mRNA G and mRNA H, over the course of 120 minutes. The data are shown in Figure 1.   Based on the data, which of the following best describes the relationship between light and the degradation of mRNA G and mRNA H?   a. mRNA G and mRNA H degrade at the same rate during morning exposure to light.   b. An increase in exposure to light causes an increase in the degradation of both mRNA G and mRNA H.   c. Exposure to more-intense afternoon light causes both mRNA G and mRNA H to degrade more rapidly in the afternoon than in the morning.   d. A longer exposure to light increases the rate of mRNA G degradation but not of mRNA H degradation.

Choose all that apply regarding gene transcription in eukaryotes: Multiple transcription factors are necessary to form the pre-initiation complex (PIC) of RNA Pol II. The 5' cap of mRNA requires the free triphosphate on the nucleotide at the 5' end. Introns must be removed from the initial RNA transcipt. Histone acetylation is a method controlling gene expression. Acetylation creates more positive charges on histones, leading to tighter binding of the proteins to DNA. Exons are removed from mRNA by the spliceosome. RNA polymerase II must completely finish an mRNA transcript before processing can begin. RNA polymerase I catalyzes the synthesis of the majority of ribosomal RNA. The hormone 173-estradiol binds to a G-protein coupled receptor to control gene transcription.

In Northern blot analysis, mRNA samples from tissues are bound to a labeled DNA probe that is complementary to the mRNA, and run on a gel to be visualized. The protein tropomyosin is known to be present in both brain and liver.  When brain and liver tissue were assayed for the presence of tropomyosin mature mRNA, bands of two different sizes were seen. Tropomyosin gene diagram (3000 bp total): Shown in attatched image If the band on the Northern blot for mRNA isolated from liver tissue is 2580 bp, whereas from brain tissue the band is 2250 bp, what is most likely? a)The two mRNAs are made from different tropomyosin DNA sequences. b)Exon 2 is alternatively spliced out of the brain mRNA. c)Introns 1 and 2 are spliced out of the brain transcript but not the liver transcript. d)Exons 1 and 3 are spliced out of the brain transcript but not the liver transcript. e)Exon 2 is alternatively spliced out of the liver mRNA.

In a competitive RNA microarray experiment, you hybridize two samples to the same chip.  Before hybridization, sample A is labeled with red fluorescence and Sample B is labeled with green fluorescence.  Spot 1142 is yellow.  What does this tell you about the relative abundance of the mRNA corresponding to this spot in the two samples? Group of answer choices It is equally abundant in both samples A and B. It is more abundant in B than A. It is more abundant in A than B. It is not present in either A or B.