GENETICS CHAPTER 15

1)Regulatory regions of a eukaryotic gene all contain which of the following sequences which regulate transcription of genes located on the same chromosome as the sequences?

, B)cis-acting regulatory sequences

2)You have identified a mutation in a gene that also seems to decrease transcription of another gene 2000 bp away from the mutation site. What regulatory sequence which may be found within another gene, has likely been mutated in this instance?,

C)enhancer sequence

3)In yeast if you want to prevent the Gal4 regulatory protein from binding near each of the GAL genes, which sequence element would you target?,

E)upstream activator sequence

4)In yeast in the presence of galactose you unexpectedly find that transcription is still blocked. Assuming Gal80 is present and functional, which other protein may be mutated to prevent transcriptional activation?,

B)Gal3

5)Galactose is absent but you find active transcription of the GAL genes. Which protein is likely mutated or absent to allow for constitutive transcription of the GAL genes?,

E)Gal80

6)Which protein binds to the silencer sequence and promotes transcriptional silencing in the presence of glucose?

B)Mig1

7)If a mouse inherits a deletion in the SHH enhancer what effect would you expect to see?,

B)abnormal limb development

8)For the following gene MspI and HpaII restriction sites and their positions are indicated here. Recall that HpaII is methylation sensitive, while MspI is not. (check actual review; picture) If this gene is being actively transcribed, how many fragments would you expect from this restriction digest?

, E)6

9) For the following gene MspI and HpaII restriction sites and their positions are indicated here. Recall that HpaII is methylation sensitive, while MspI is not. (check actual review; picture) If this gene is methylated, which of the following combinations of DNA fragments would you expect from this restriction digest?,

B)4 bands = 100 bp, 200 bp, 800 bp, and 900 bp.

10) Which sequences would likely have both a nucleosome-depleted region (NDR) and a poly A/T tract to attract transcriptional activators to a transcription start sequence?

C)open promoters

11)Molecular biologists can determine experimentally whether a region of DNA contains closed chromatin or open chromatin by assessing the sensitivity of the region to __________.

E)DNAse

12)Chromatin remodeling involves both sliding and relocating of the nucleosomes. Which eukaryotic chromatin remodeling complex is likely involved?

C)SWI/SNF complex

13)If you want to affect chromatin packaging which amino acid could you mutate to affect both histone acetylation and methylation patterns?,

D)lysine

14)A region of chromatin has recently become DNAse I hypersensitive. Which enzyme has been activated to cause this change in chromatin structure?

B)histone acetylase

15)Prader-Willi syndrome is a genetic disorder involving a partial deletion of chromosome 15q on the paternal chromosome. When both copies of a gene (or chromosome) are functional but only one is expressed this is an example of __________.,

C) genomic imprinting

16)When CpG islands are unmethylated __________.,

A)chromatin in the promoter region is open, allowing access by transcription factors and RNA polymerase

17)Typically methylation of nucleosome N-terminal tails leads to __________.,

C)tighter packaging of the chromatin and reduced transcription

18)Typically acetylation of histone tails leads to __________.,

B)relaxed packaging of the chromatin and increased transcription

19)The imprinting control region (ICR) involved in genomic imprinting on chromosome 15 is what type of sequence?

B)insulator

20)Inherited mutations in the Xist promoter lead to defects in which epigenetic process?

B)X-inactivation

21)During RNAi what do miRNAs target for destruction?,

C)mRNAs

22)Many types of cancer are known to overexpress the receptor protein tyrosine kinase. Which molecular technique can be used to reduce expression of an oncogene in vitro?

C)RNAi

1)Which molecules bind regulatory sequences of DNA to encourage positive regulation of transcription?

activator proteins

2)Which protein complex directs DNA bending into loops that contact RNA polymerase and transcription factors bound at the core promoter or with protein complexes bound to proximal promoter elements?

enhanceosome

3)What are three proteins or groups of proteins you would expect to find bound to the core promoter region in eukaryotes?

TBP, GTFs, and Pol II

4)In gal+ yeast, what is the product of the galactose utilization pathway?,

glucose-1-phosphate

5)In the GAL gene system which protein acts as an activator protein through its transcription-initiating effect?,

Gal4

6)In the GAL gene system which protein binds to the activation domain of the activator protein, ultimately blocking transcription in the absence of galactose?,

Gal80

7)Gal4 is mutated such that it still binds to the DNA but cannot interact with Gal80. What effect would you expect to see in the absence of galactose?

transcriptional activation

8)Gal80 is mutated such that it cannot interact with Gal3. What effect would you expect to see in the presence of galactose?

Transcription is blocked.

9)Eukaryotes use these highly specialized enhancer elements which regulate the transcription of multiple genes packaged in complexes of closely related genes (e.g., β-globin).,

locus control regions (LCRs)

10)What are the protein-binding sequences that direct enhancers to interact with the intended promoter and that block communication between enhancers and other promoters?

insulator sequences

11)For the following gene which mutant likely has lost its enhancer? (check review; table)

, mutant 3 (region 500-800)

12)For the following gene which type of regulatory sequence has likely been deleted in mutant 1? (check review; table),

silencer

13)For the following gene you notice the following results. (check review; table) What type of sequence has been mutated in mutant 4?,

tissue-specific (lung) promoter

14)What are the three mechanisms by which chromatin remodelers can move nucleosomes?

nucleosome sliding, nucleosome repositioning, and removal of nucleosomes

15)In yeast which gene would you expect to be activated during phosphate starvation?,

PHO5

16)In vertebrates and plants, what types of modifications to the N-terminal tails of histones lead to heterochromatin formation?,

deacetylation and methylation

17)Which of the four nucleotides are typically methylated in "islands" resulting in closed chromatin structure?,

cytosines

18)If you block histone deacetylase what effect would you expect to see on transcriptional activity?,

continued/prolonged transcription

19)What effect does methylation of CpG islands have on human promoters?

reduced transcription

20)What gene is critical for establishment of X-inactivation in mammals?

Xist

21)Which protein complex binds dsRNA fragments to generate ssRNAs for RNAi?

RNA-induced silencing complex (RISC)

22)Which enzyme cuts dsRNA into 21-25 bp fragments during RNAi?

Dicer

1)Gal4 binding leads to the formation of a multiprotein complex known as the ________ which is an enhanceosome that forms after the activator protein binds.

, mediator

2)In the GAL gene system, ________ are cis-acting regulatory elements, and ________ protein is a trans-acting regulatory protein.

UASG; Gal4

3)Demethylation and acetylation lead to open chromatin structure and are associated with ________ regions of genomes.

euchromatic

4) ________ in Drosophila results from the movement of the transcriptionally active w+ allele into the centromeric heterochromatin region of the fruit-fly X chromosome.

Position effect variegation (PEV)

5)In animals the ________ enzyme cuts pri-miRNA to produce miRNA.,

Drosha