Concept explainers
Telomerase is an enzyme that is responsible for the addition of telomeric units or repeats to the end of the bacterial chromosome. This enzyme is critical for maintaining the length of the telomere. Mammalian somatic cells lack the activity of this enzyme and therefore, results in the shortening of telomeres in each of the
Explanation of Solution
A phenomenon in which the normal diploid cells end the division process is known as cellular senescence. The somatic cells present in the human as well as the majority of animal exhibit the feature of senescence. Such cells undergo division for a particular number of generations and then cease their activity.
A portion of the telomeres (cap ends of the chromosome) is lost during every division until the complete telomeric region disappears as well as the essential genes are lost. On the other hand, the yeast Saccharomyces cerevisiae is a single-celled microbe that continues to grow as well as it divides throughout its life cycle. Therefore, senescence might be the possible reason for the cessation of telomerase activity in somatic cells.
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Chapter 15 Solutions
Prescott's Microbiology
- Three different chitin synthase genes control chitin synthesis in S. cerevisiae. Discuss what will happen to the budding yeast if a mutation occurs in each of the genes below: CHSI CHSII CHSIIIarrow_forwardThe sequences of DNA bases below represent parts of the genes responsible for the production of one type of protein, an enzyme, produced by Botana curus and Species X, Y, and Z Under each DNA sequence, write the complementary messenger RNA base sequences that each of these gene fragments would produce. Note: Unlike during DNA replication, in the production of messenger RNA, the DNA base “A” specifies the RNA base “U.”. Use the universal genetic code table provided (see Universal Code attachment) to translate the messenger RNA base sequences into sequences of amino acids in the protein produced by each species. Write the sequences of amino acids under the messenger RNA sequences.arrow_forwardIf a mutation that inactivated telomerase occurred in acell (telomerase activity in the cell = zero), what do youexpect the outcome to be?arrow_forward
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- Whether the statement "In E. coli, where the replication fork travels at 500 nucleotide pairs per second, the DNA ahead of the fork-in the absence of topoisomerase-would have to rotate at nearly 3000 revolutions per minute" is true or false.arrow_forwardAnswer the following two questions. Ensure that your answer is separated into two parts, labelled A and B. a. Why is telomerase used by some eukaryotic cells but not prokaryotic cells? b. Clearly explain what the consequence is for a eukaryotic cell that lacks telomerase.arrow_forwardYou conducted an experiment to determine the mechanism of DNA replication in the hypothetical organism Fungus mungus. Your data shows that synthesis of newly replicated DNA from F. mungus is discontinuous on both strands of the replication fork. Does this result support or not support the hypothesis that F. mungus replicates its DNA by the same mechanism as yeast? Briefly explain your answer.arrow_forward
- Why would telomerase be considered a reverse transcriptase?arrow_forwardIf deoxyribonucleotides that lack the 3’-OH groups are added during the replication process, what do you expect will occur? Describe what happens when a nonsense mutation is introduced into the gene encoding transposase within a transposon. A pure culture of an unknown bacterium was streaked onto plates of a variety of media. You notice that the colony morphology is strikingly different on plates of minimal media with glucose compared to that seen on trypticase soy agar plates. How can you explain these differences in colony morphology?arrow_forwardAnswer the following two questions. Ensure that your answer is separated into two parts, labelled A and B. a. points Why is telomerase used by some eukaryotic cells but not prokaryotic cells? b. Clearly explain what the consequence is for a eukaryotic cell that lacks telomerase.arrow_forward
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