An advantage of translesion DNA polymerases is they can replicate ( ), but a disadvantage is they ( ).

Question

An advantage of translesion DNA polymerases is they can replicate (           ), but a disadvantage is they (                                    ).

BlackTom AI · Accepted Answer

Translesion synthesis (TLS) polymerases are specialized DNA polymerases that can copy past damaged bases in the template strand but do so with reduced accuracy.

1) Relevant knowledge points and concepts:
- Replicative polymerases stall at DNA lesions (e.g., thymine dimers, abasic sites). TLS polymerases (Y-family: Pol η, ι, κ; Rev1; and the B-family member Pol ζ) are recruited to bypass these lesions. 
- Structural basis: TLS polymerases have a more open active site that accommodates distorted templates. They generally lack 3′→5′ exonuclease proofreading activity. 
- Consequence: lesion bypass prevents replication fork collapse (an advantage) but the lack of proofreading and flexible active site make TLS polymerases error-prone (a disadvantage).

2) Step-by-step reasoning:
- When the replication fork encounters a lesion, replicative polymerases cannot incorporate across the damaged base → TLS polymerase is recruited.
- TLS polymerase inserts a nucleotide opposite the lesion and often extends past it, allowing replication to continue.
- Because TLS polymerases accept distorted base pairs and lack proofreading, incorrect nucleotides are more likely to be incorporated.

3) Calculations:
- No numeric calculations are required for this conceptual question.

4) Why the correct answer is correct:
- The phrase “over damaged DNA” captures the defining functional advantage of TLS polymerases: they synthesize DNA across lesions that would block normal polymerases.
- “Have low fidelity” correctly describes their higher error rate due to the open active site and absence of exonuclease proofreading, which increases mutagenesis risk.

5) Why other options are incorrect:
- “Very quickly, have low fidelity”: speed is not the defining advantage; TLS may be slower or regulated—speed is not the key point.
- “Over damaged DNA, are very slow”: while some TLS reactions can be slower, the primary disadvantage noted in textbooks is low fidelity, not slowness.
- “Very accurately, are very slow”: TLS polymerases are not very accurate; this directly contradicts established biochemical evidence.

6) Conclusion:
Therefore the correct choice is “over damaged DNA, have low fidelity,” which matches the provided answer.

An advantage of translesion DNA polymerases is they can replicate ( ), but a disadvantage is they ( ).单项选择题

类似问题

An advantage of translesion DNA polymerases is they can replicate ( ), but a disadvantage is they ( ).

What was the world's first widely adopted biodiversity policy?

The aim of the Paris Agreement is to ensure that the earth’s preindustrial temperature is not exceeded by more than º Celsius.

The IPCC's mission is to Blank ______.

Why have most international agreements for environmental protection been based on the honor system?

As was exhibited with the Montreal Protocol and the encouragement of reduced CFC production, trade can be an effective tool to compel compliance with international treaties.

The Stockholm Declaration and UNEP were the result of the Blank ______ first conference on the Human Environment in 1972.

In addition to the direct mission of the Convention on International Trade in Endangered Species (CITES), why was CITES so important?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单