The hok gene in the R1 plasmid of the bacterium E - VCE - SSCE Biology - Question 12 - 2010 - Paper 1
Question 12
The hok gene in the R1 plasmid of the bacterium E. coli codes for a toxic protein that causes cell death. The sok gene in the same plasmid codes for an antisense reg... show full transcript
Worked Solution & Example Answer:The hok gene in the R1 plasmid of the bacterium E - VCE - SSCE Biology - Question 12 - 2010 - Paper 1
Step 1
A. hok mRNA would be translated if sok mRNA was absent.
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Answer
This statement is true. If sok mRNA is not present, there is no antisense regulation to inhibit the translation of hok mRNA. Consequently, the translation of the toxic protein would proceed, leading to cell death.
Step 2
B. hok DNA would be unable to be transcribed if sok mRNA is present.
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Answer
This statement is false. The presence of sok mRNA does not impede the transcription of hok DNA; rather, it allows for the formation of the RNA complexes that inhibit the translation of the resulting mRNA.
Step 3
C. sok mRNA would have the same nucleotide sequence as hok mRNA.
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Answer
This statement is false. Sok mRNA is an antisense RNA that binds specifically to the complementary sequence of hok mRNA, meaning they are not identical but are complementary in certain regions.
Step 4
D. an E. coli cell without any plasmids would be killed by the toxic protein.
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Answer
This statement is true, as the toxic protein is produced from the hok gene in the plasmid. If an E. coli cell lacks this plasmid, it would not produce the toxic protein and thus would not be at risk of cell death from it.
