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
- The 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_forwardTelomerase is not active in most human cells. Some cancer biologists have suggested that activation of the telomerase gene would be a requirement for a cell to become cancerous. Explain why this might be the case.arrow_forward
- You are a physician who has diagnosed a patient with a genetic condition that results in telomerase with lower than normal enzymatic activity. How might you have diagnosed this disease? What symptoms should be a clue? Explain.arrow_forwardYeast cells are eukaryotes, and they require a functional secretory pathway to grow and to maintain cellular organization. But surprisingly, when SRP is removed from yeast cells by deleting the relevant genes, the cells are still alive (although they grow slowly). a) How can yeast survive without SRP? Propose two alternative hypotheses. b) How might electron microscopy of normal and SRP-deficient yeast cells help you to distinguish between these two hypotheses?arrow_forwardWhat would be the likely result of expressing telomerase in somatic cells? Immortality of gametes premature aging lower rates of replication formation of cancerarrow_forward
- n yeast cells, telomerase remains active and maintains telomeres of about 300 base pairs. Propose what would happen to the telomeres over time in a yeast lineage in which the following mutations were created. The gene encoding the catalytic subunit of the telomerase is deleted.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_forwardScientists identify a tumor cell in rats that divides more rapidly in the presence of galactose. When they sequence the DNA of the tumor cells, they identify retroviral DNA. Explain what circumstances might have occurred that produced this phenotype.arrow_forward
- You 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_forwardWhy would telomerase be considered a reverse transcriptase?arrow_forwardUse the first photo to answer the following questions.arrow_forward
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