5. Alpha amanitin is a drug that binds RNA polymerase and prevents it from funct

Question

5. Alpha amanitin is a drug that binds RNA polymerase and prevents it from functioning in the cell (this is the compound that is found in poison mushrooms). The reason people die when they consume alpha amanitin is:

a) Alpha amanitin prevents gene expression from occurring in the cell

b) DNA replication is directly inhibited by alpha amantin

c) Alpha amanitin binds tightly to the messenger RNAs that are made in the cell, preventing translation

d) Alpha amanitin binds to nuclear pores preventing the transport of messenger RNA into the cytoplasm

6. In order for transcriptional initiation to begin in E. coli the following elements are needed:

a) an origin and RNA polymerase

b) initiator protein and a promoter

c) the sigma subunit of RNA polymerase and an RNA template

d) RNA polymerase and a promoter

e) helicase and primase

Questions 7 and 8. You are studying two species of closely related snakes, one species lives in sandy desert area and has pale tan skin and the species lives in a volcanic rock area and has dark brown skin. You a sequence the DNA from each type of snake and discover a gene encoding a protein that transports pigment into the skin cells. The pigment transporter protein is responsible for skin color. When you analyze the DNA coding sequence of the pigment transporter from each snake you find these two DNA sequences (hash marks have been added to indicate the reading frame):

pale tan snake: GCG/TTG/GAC/TGC/ACC (DNA template strand) CGC/AAC/CTG/ACG/TGG (complementary strand) dark brown snake: ACG/TTG/GAC/TGC/ACC (DNA template strand) TGC/AAC/CTG/ACG/TGG (complementary strand)

7. From these sequences you conclude:

a) that the amino acid sequence of the pigment transporters for the two proteins are almost identical

b) that the amino acid sequence of the pigment transporters for the two proteins are very dissimilar

c) that the amino acid sequence of the pigment transporters for the two proteins are identical

8. Since the skin color is different in each snake, you conclude from the sequence data above that:

a) the genetic code in the skin cells in each of these snakes is different

b) the DNA sequence encoding the entire gene for pigment transporters in these two snakes is different

c) that one of the codons in the gene for the pigment transporter in these two snakes is different

9. You are analyzing eukaryotic cells that have been exposed to the radioactive uracil. In most cells the radioactive uracil is initially localized in the nucleus and then moves from the nucleus to the cytoplasm. However, you observe that in some cells the radioactive molecules stay in the nucleus and never arrive in the cytoplasm. This is most likely a defect in:

a) the transcription of the DNA

b) the processing of the mRNA

c) the translation of the RNA

d) the labeling of the RNA

e) the replication of the DNA

10. Which of the following is true of both eukaryotic and bacterial transcription? (select all that are true)
a) Transcription factors must bind the promoter before RNA polymerase initiates transcription

b) Messenger RNAs must be spliced before translation begins in order to produce the appropriate gene product

c) During transcription only one DNA strand is used as a template to make the messenger RNA

d) Termination of transcription occurs when the RNA polymerase transcribes a hairpin structure in the RNA followed by a string of U

Explanation / Answer

5
(A) Alpha amanitin prevents gene expression from occurring in the cell

6
(C) the sigma subunit of RNA polymerase and an RNA template

7
(A) that the amino acid sequence of the pigment transporters for the two proteins are almost identical

8
(C) that one of the codons in the gene for the pigment transporter in these two snakes is different

9
(C) the translation of the RNA

10
(A) Transcription factors must bind the promoter before RNA polymerase initiates transcription
(C) During transcription only one DNA strand is used as a template to make the messenger RNA

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