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Latihan TOEFL Listening 13: Lecture: CRISPR Gene Editing

Ini transkrip percakapan atau kuliah untuk latihan listening. Coba pahami isinya, lalu jawab 10 soal di bawah.

CRISPR-Cas9, often simply called CRISPR, has transformed genetic research since its adaptation as a gene-editing tool roughly a decade ago. The system originated as a natural defense mechanism in bacteria, which use it to recognize and destroy the genetic material of invading viruses by storing snippets of viral DNA and using them to guide a cutting enzyme toward matching sequences in the future.

Researchers repurposed this bacterial defense system by designing guide sequences that direct the Cas9 enzyme to cut a specific location within virtually any organism's genome. Once the DNA is cut, the cell's own repair mechanisms can be harnessed either to disable a gene entirely or, with the addition of a template sequence, to introduce a precise, intended genetic change.

While CRISPR has accelerated basic research and shown promise for treating certain genetic diseases, its use also raises significant ethical questions, particularly regarding edits made to human embryos that would be passed on to future generations. Unlike edits made to an individual's existing cells, which affect only that person, germline edits could alter the genetic makeup of an entire lineage, prompting most of the international scientific community to call for a moratorium on clinical use of such edits until broader ethical and safety questions are resolved.

Soal

1. What is the main purpose of this lecture?

  1. Explaining how CRISPR works and the ethical questions it raises
  2. Arguing that all genetic research should be banned
  3. Comparing CRISPR to older laboratory techniques in detail
  4. Describing the complete history of bacterial evolution
Lihat jawaban dan pembahasan

Jawaban: A. Explaining how CRISPR works and the ethical questions it raises

Lecture menjelaskan mekanisme CRISPR lalu isu etis yang ditimbulkannya.

2. According to the lecture, where did the CRISPR system originally come from?

  1. A natural bacterial defense mechanism against viruses
  2. Human immune cells
  3. A synthetic chemical created in a laboratory
  4. Plant cells
Lihat jawaban dan pembahasan

Jawaban: A. A natural bacterial defense mechanism against viruses

Disebutkan eksplisit sistem ini berasal dari mekanisme pertahanan alami bakteri.

3. According to the lecture, what does the guide sequence do in gene editing?

  1. Destroys the entire genome
  2. Directs the Cas9 enzyme to cut a specific location in the genome
  3. Repairs damaged skin cells
  4. Prevents any genetic mutation from occurring
Lihat jawaban dan pembahasan

Jawaban: B. Directs the Cas9 enzyme to cut a specific location in the genome

Disebutkan eksplisit fungsi guide sequence ini.

4. It can be inferred that without a template sequence, cutting DNA with CRISPR would likely

  1. Always kill the cell immediately
  2. Have absolutely no effect on the cell
  3. Only work in bacteria
  4. Disable the targeted gene rather than introduce a precise change
Lihat jawaban dan pembahasan

Jawaban: D. Disable the targeted gene rather than introduce a precise change

Disebutkan tanpa template, perbaikan sel bisa dipakai 'to disable a gene entirely', sementara template diperlukan untuk perubahan presisi.

5. Why does the lecturer distinguish between germline edits and edits to an individual's existing cells?

  1. To compare the cost of each procedure
  2. To describe a difference in laboratory equipment used
  3. To argue that both types of edits are equally safe
  4. To explain why germline edits raise greater ethical concern, since they affect future generations
Lihat jawaban dan pembahasan

Jawaban: D. To explain why germline edits raise greater ethical concern, since they affect future generations

Perbedaan ini menjelaskan mengapa germline edit menimbulkan kekhawatiran etis yang lebih besar.

6. The word 'moratorium' as used in the lecture is closest in meaning to

  1. A permanent legal ban
  2. A type of scientific award
  3. A financial reward
  4. A temporary halt or suspension of an activity
Lihat jawaban dan pembahasan

Jawaban: D. A temporary halt or suspension of an activity

'Moratorium' berarti penghentian sementara suatu kegiatan, bukan larangan permanen.

7. According to the lecture, what has most of the international scientific community called for regarding germline edits?

  1. Increased funding with no restrictions
  2. A complete ban on all CRISPR research
  3. Immediate widespread clinical application
  4. A moratorium on clinical use until safety and ethical questions are resolved
Lihat jawaban dan pembahasan

Jawaban: D. A moratorium on clinical use until safety and ethical questions are resolved

Disebutkan eksplisit komunitas ilmiah internasional menyerukan moratorium ini.

8. It can be inferred that CRISPR's adaptation as a gene-editing tool represents

  1. An entirely artificial invention with no natural precedent
  2. A technique that only works in bacteria
  3. A repurposing of a mechanism that evolved for an entirely different biological function
  4. A decades-old, well-established medical practice
Lihat jawaban dan pembahasan

Jawaban: C. A repurposing of a mechanism that evolved for an entirely different biological function

CRISPR awalnya adalah mekanisme pertahanan bakteri alami yang kemudian dimanfaatkan ulang oleh peneliti.

9. According to the lecture, how do bacteria naturally use this system?

  1. To reproduce more quickly
  2. To produce energy for the cell
  3. To recognize and destroy the genetic material of invading viruses
  4. To communicate with other bacteria
Lihat jawaban dan pembahasan

Jawaban: C. To recognize and destroy the genetic material of invading viruses

Disebutkan eksplisit fungsi alami sistem ini pada bakteri.

10. Why does the lecturer mention that CRISPR has 'accelerated basic research'?

  1. To argue that ethical concerns are therefore unimportant
  2. To criticize researchers who use older techniques
  3. To acknowledge a significant benefit before discussing the ethical concerns
  4. To explain how research funding is allocated
Lihat jawaban dan pembahasan

Jawaban: C. To acknowledge a significant benefit before discussing the ethical concerns

Ini menyeimbangkan pembahasan dengan mengakui manfaat sebelum membahas kekhawatiran etisnya.

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