Professor: Today we’ll revisit the first mammal cloned from an adult cell—Dolly the sheep—and tackle a persistent claim: that Dolly was “weak” because she was cloned. To evaluate that, we need the biology and the context.
Dolly was created in 1996 by somatic cell nuclear transfer (SCNT). Researchers removed the nucleus from an unfertilized sheep egg and replaced it with a nucleus from an adult mammary-gland cell. After activation, the reconstructed egg began dividing and was implanted into a surrogate. Here is a crucial datapoint: success was extraordinarily low—hundreds of reconstructed eggs, many early losses, and one live birth, Dolly. I mention these numbers not to dramatize the achievement but to highlight how biologically demanding reprogramming is.
Why demanding? In an adult cell, gene activity is controlled by a dense pattern of chemical marks—an epigenetic landscape. SCNT has to erase and reset much of that landscape so the donated nucleus can behave like an embryo. When the reset is incomplete, development can go awry. In livestock, we’ve seen imprinting errors and a condition called “large offspring syndrome,” both linked to reprogramming glitches. So, if a clone appears unhealthy, epigenetics is a prime suspect.
Now, what about Dolly specifically? Two facts fed the “weakness” story. First, she developed arthritis at about five years of age—early for a Finn-Dorset sheep. Second, tests suggested her telomeres—the protective tips of chromosomes—were shorter than typical for her chronological age. Short telomeres can be a sign of cellular aging, so people concluded that Dolly was born “old.”
However, the evidence is less clear-cut. Arthritis can be influenced by housing, activity, genetics—factors not unique to cloning—and a single animal is a poor basis for sweeping generalizations. As for telomeres, yes, Dolly’s appeared shorter, but subsequent work on other cloned sheep from the same cell line showed normal health into later life, with no dramatic early-aging syndrome. In other words, telomere length in clones can vary and does not invariably predict frailty.
There’s also the matter of mitochondria. The egg supplies the mitochondria, which carry their own DNA. That means a clone has nuclear DNA from the donor but mitochondrial DNA from the egg donor—creating a potential nuclear–cytoplasmic mismatch. Some researchers have speculated that certain pairings might stress metabolism, but evidence remains mixed.
So why did Dolly die at six? She was euthanized due to progressive lung disease consistent with ovine pulmonary adenocarcinoma, a contagious condition caused by a retrovirus. That diagnosis points more to an infectious exposure than to a built-in weakness of cloning. It’s tragic, but not a smoking gun for “clones are fragile.”
To sum up: SCNT is inefficient and biologically risky, primarily because epigenetic reprogramming is hard. Those risks can produce abnormalities. But Dolly’s case—arthritis, short telomeres, viral lung disease—doesn’t prove that cloning necessarily yields weak animals. The fair conclusion is nuanced: early clones faced elevated developmental risks, yet individual outcomes reflect a blend of reprogramming quality, husbandry, infection control, and plain chance.
Questions:
1. What is the professor’s main point about Dolly’s so-called “weakness”?
The point is a potential source of stress due to mixed origins of nuclear vs. mitochondrial genomes.
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Correct Answers: 0
Incorrect Answers: 0
II. Reading
1. Step 1. Read the text below
Reading + Test Time — 18 minutes
18:00
First scan the questions on author’s purpose and negative factual information. Then read the passage carefully.
Watch for linking phrases and contrasts at the beginning and end of paragraphs.
Read the questions marked redunder the text first!
Paragraph 1
In everyday conversation, cloning is often imagined as producing a carbon-copy of an entire organism. Biologists, however, use the term more broadly to describe making genetically identical copies at different scales—genes, cells, tissues, and, in rare cases, whole organisms. This umbrella meaning matters because the word gathers together methods that differ sharply in technical steps, aims, and ethical implications.
Paragraph 2
One of the earliest approaches to organismal cloning is embryo splitting, sometimes called twinning. In this procedure, an early embryo at the stage of only a few cells is mechanically divided so that each half can continue developing on its own. The result is analogous to naturally occurring identical twins: two embryos with the same nuclear DNA, both derived from a single fertilized egg. The method does not involve replacing DNA or re-engineering cells; it simply separates developmental potential that was already present. Because it relies on a fertilized egg, embryo splitting is best viewed as a refinement of assisted reproduction rather than a radical departure from it.
Paragraph 3
More technically demanding is somatic cell nuclear transfer (SCNT), the technique that produced the sheep Dolly in the 1990s. SCNT begins with an unfertilized egg cell from which the nucleus—containing almost all the cell’s DNA—has been removed. The emptied egg then receives a nucleus from a somatic (body) cell taken from an animal that one hopes to clone. If the reconstructed egg is coaxed to begin dividing, it forms an embryo carrying the donor’s nuclear genome. Unlike embryo splitting, SCNT uses DNA from a mature cell that has long since committed to a specialized identity. Reverting that nucleus to an embryonic state is biologically formidable because the pattern of chemical marks that control gene activity—the epigenetic landscape—must be widely reset. Failures in this reprogramming help explain why SCNT remains inefficient, with many embryos failing to implant or develop normally.
Paragraph 4
A third path, sometimes mentioned alongside cloning but distinct in goal, is the generation of induced pluripotent stem cells (iPSCs). Here, researchers reprogram an adult cell back to a flexible, embryonic-like state by altering the expression of a handful of regulatory genes. iPSCs can be expanded into many kinds of tissues genetically matched to the donor. Unlike SCNT, the aim is not to produce an embryo for reproduction but to generate patient-specific cells for research or potential therapy. For that reason, iPSC work is often described as a “cloning” of cellular potential rather than an attempt at making a copy of an entire organism.
Paragraph 5
Cloning’s conceptual boundaries become clearer when we look at organisms that reproduce asexually in nature. Many plants, some invertebrates, and a few vertebrates can generate near-identical offspring from cuttings, budding, or parthenogenesis. In agriculture and horticulture, humans harness this clonal capacity through vegetative propagation and micropropagation, producing uniform crops or disease-free stock. These examples remind us that cloning is not solely a laboratory invention; it also names a spectrum of strategies by which life repeats successful genetic combinations.
Paragraph 6
Despite their shared label, these methods diverge in their ethical and practical profiles. Embryo splitting stays closest to conventional reproduction, yet it raises questions about the number and disposition of embryos. SCNT carries the scientific promise of copying genotypes valuable for conservation or agriculture, but its low success rates and risks of abnormal development make it controversial, especially in mammals. iPSC technology sidesteps the creation of embryos, thereby avoiding some objections, but it introduces others—such as how to regulate embryo-like structures that iPSCs can form under certain conditions. Across all methods, debates concentrate on welfare considerations, the moral status of early developmental stages, and whether the benefits justify the risks.
Paragraph 7
Because language shapes policy, it is important to distinguish the techniques rather than treat them as interchangeable. When “cloning” is used without qualification, the public may assume that any laboratory work aims to produce a copy of a person or animal. In practice, most contemporary research focuses on cellular models and tissues that never approach reproduction. Clear terminology helps reconcile scientific goals with social expectations and legal rules.
Questions:
1. According to paragraph 2, what is a defining feature of embryo splitting? [Detail]
Here it means “treated as the same/indistinguishable.”
9. In the paragraph below, indicate where the following sentence best fits. This widespread assumption can distort public debate and complicate regulation.[Sentence Insertion]
Because language shapes policy, it is important to distinguish the techniques rather than treat them as interchangeable. (A) When “cloning” is used without qualification, the public may assume that any laboratory work aims to produce a copy of a person or animal. (B) In practice, most contemporary research focuses on cellular models and tissues that never approach reproduction. (C) Clear terminology helps reconcile scientific goals with social expectations and legal rules. (D)
It follows the sentence describing the public’s assumption—so after (A), i.e., option B.
10. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by dragging the letters of the three answer choices that express the most important ideas into the box. [Summary]
Cloning encompasses multiple methods with distinct goals, challenges, and ethical profiles.
A. Embryo splitting produces twin-like embryos by dividing an early fertilized egg and resembles assisted reproduction.
B. SCNT reconstructs an embryo using a somatic nucleus but remains inefficient due to epigenetic reprogramming challenges.
C. iPSCs are primarily used to create cloned animals for agriculture and conservation.
D. Natural and agricultural examples show that genetic copying is not confined to laboratories.
E. Because “cloning” covers diverse methods and aims, precise terminology is crucial for aligning science, ethics, and policy.
F. Most cloning methods are ethically identical because they produce the same outcomes.
Pregnancy Robots: A New Path for Assisted Reproduction?
In recent years, research groups in China and a handful of labs abroad have publicized prototypes of so-called pregnancy robots—ex-utero systems that aim to carry a human pregnancy outside the body under strict medical oversight. Advocates claim these platforms could reduce maternal risk, expand options for families facing infertility, and lower neonatal complications. Their method combines three tightly integrated components:
1) Ex-utero gestational chamber.
A sealed bioreactor—sometimes called an artificial womb—circulates sterile amniotic fluid around the embryo/fetus while micro-actuators reproduce gentle uterine movements. Gas exchange and temperature are stabilized by membranes that mimic physiological conditions from implantation through late gestation.
2) Synthetic placenta with hormonal control.
Instead of connecting to a pregnant person’s blood, a microfluidic “robotic placenta” delivers oxygen and nutrients and removes waste through ultra-thin exchange membranes. A separate module administers tiny, precisely timed doses of pregnancy hormones (progesterone, estrogens, placental lactogen, etc.) to reproduce the endocrine environment believed to guide normal development.
3) AI obstetrician (closed-loop monitoring).
High-resolution ultrasound arrays, optical sensors, and fetal ECG feed a machine-learning controller that continually adjusts fluid flow, pressure, and hormone schedules for personalized gestation. Clinicians can supervise remotely; alarms trigger human intervention if any parameter leaves its safe range. Proponents argue that, together, these features will make ex-utero gestation safe, scalable, and ethically manageable under hospital regulations.
If validated in trials, pregnancy robots could supplement neonatal intensive care, minimize preterm complications, and offer a new path to parenthood while relieving pressure on overburdened maternity units. Supporters conclude that the combination of bioreactor stability, synthetic placental exchange, and AI control brings truly viable ex-utero pregnancy within reach.
Step 2. Listen to part of a lecture below and take notes.
Lecture (Biodevices Seminar): Why the Promises of “Pregnancy Robots” Are Premature
Professor: The robot-based reproduction technology sketches an appealing blueprint, but each of its three pillars faces obstacles that are far from solved.
First, the ex-utero gestational chamber. A uterus is not just warm fluid and gentle motion. Early pregnancy depends on implantation into maternal tissue, immune tolerance from the decidua, and extremely dynamic signaling between embryo and parent. We cannot recreate that tissue remodeling or the spiral-artery transformation that protects the placenta from pressure surges. Even later in gestation, maintaining correct shear stress, microbiome exposure, and mechanical cues matters for lung and gut maturation. Current chambers control temperature and flow, yes—but they lack the living interface that makes those cues adaptive. Without it, small instabilities can snowball into growth restriction or organ malformation.
Second, the synthetic placenta and hormone module. Gas and nutrient exchange in a real placenta occurs across billions of microvilli, with anti-clotting surfaces and exquisitely tuned gradients. Microfluidic membranes foul, micro-clots form, and oxygen carriers behave unpredictably under sustained flow. More importantly, endocrine control is not a simple “set the level” problem. Placental hormones follow pulsatile, circadian, and feedback-driven patterns that shift week by week and differ across pregnancies. A bottled cocktail cannot substitute for that complexity, and we lack robust biomarkers to tell us in real time whether our “hormone mimicry” is helping or quietly disrupting imprinting and other epigenetic programs.
Third, the AI obstetrician. Closed-loop control only works if the sensors are comprehensive and the training data cover edge cases. We do not have high-frequency, artifact-free measurements of fetal perfusion, neurodevelopment, or placental microcirculation over months. Ultrasound and optical signals are noisy; many relevant variables are unobservable. A model trained on limited animal data will face a distribution shift with human fetuses—exactly where prediction errors are least tolerable. Add unresolved issues of verification, cybersecurity, and liability, and it’s hard to see regulators approving a system that might make autonomous adjustments on the basis of uncertain inferences.
So while the inventors highlight stability, exchange, and control, the reality is missing maternal tissue biology, lacks a true placental analog, and depends on AI that cannot yet be proven safe across all scenarios. Until those foundations change, “pregnancy robots” remain an intriguing research direction—but not a feasible or ethical replacement for human gestation or established neonatal care.
Important!: Write out the three main ideas and their elaborations/illustrations/details that the lecturer provides. You should connect the points made in the lecture to the points made in the reading! When you hear the question, click to show the passage and question and begin your response.
Summarize the three components of the “pregnancy robot” described in the reading
(ex-utero gestational chamber, synthetic placenta with hormonal control, and AI obstetrician).
Then explain how the professor casts doubt on the feasibility of each component.
Be sure to link each lecture point to the corresponding claim from the reading and use concrete details from the lecture.
Summarize the points made in the lecture, being sure to explain how they cast doubt on the points made in the reading.
[Overview] The text under analysis claims that pregnancy robots can succeed via a gestational chamber, a synthetic placenta with hormonal control, and an AI obstetrician.
The lecture challenges those claims, arguing that missing maternal tissue biology, lack of a true placental analog, and unsafe/insufficient AI control make the proposal premature.
[Body] Firstly, the reading argues a stable ex-utero chamber can mimic the womb, whereas the professor says implantation/decidual biology and spiral-artery remodeling can’t be replicated, risking maldevelopment.
Secondly, the reading’s synthetic placenta and hormone module are questioned: membranes foul, micro-clots form, and endocrine rhythms are complex; the lecturer warns about disrupted imprinting.
Finally, the AI controller is criticized: sensors are incomplete, key variables are unobservable, and distribution shift undermines safety; verification, cybersecurity, and liability remain unresolved.
[Conclusion] Therefore, the lecture systematically casts doubt on each of the reading’s three pillars with technical and ethical counterpoints.
Dear students, this week’s prompt is intentionally provocative: Would human cloning “destroy” the institution of the family, or reinvent it? Assume cloning is safe, legal, and regulated. Think concretely about legal parentage, identity and expectations for the child, and inequality/access. I’m looking for clear positions grounded in reasons and examples.
.
Student 1: Mina
I don’t think cloning would destroy families; it would expand them. Families already come in many forms—adoption, IVF, blended households—yet the core is care and commitment, not DNA ratios. With strict consent and psychological support, cloning could help infertile people become parents and keep children out of long fertility queues. The “identity pressure” concern is real, but that’s a parenting issue, not a technology issue. We already manage expectations with gifted kids or donor-conceived children through counseling and disclosure norms. Likewise, the law can define parentage clearly (e.g., nuclear donor + gestational parent as legal parents) just as it did for IVF. In short, responsible policy would let cloning reinvent family ties without undermining them.
Student 2: David
I’m convinced cloning would erode the family by turning kids into “legacy projects.” A cloned child might face relentless comparisons to the donor—same face, same expectations—which could distort identity formation. Legal parentage would also be messy: if the nuclear donor, gestational parent, and a partner all claim parental status, custody disputes could multiply. Finally, cloning would likely be expensive at first, widening inequality—wealthy families could select fashionable traits while others cannot, pushing social stigma onto the child and normalizing instrumental reasons for having kids. Adoption and existing reproductive tech already provide paths to parenthood without these new risks, so I don’t see a compelling reason to cross this line.
Writing Question:
Write a response (about 120 words) stating your opinion on the issue. Be sure to:
State your own view clearly. It brings you more points if your opinion is different from those of the students.
This is a challenging topic, but I think that …. I strongly agree with Emily’s//James' idea that …. I’d add that …………. WhileJames/Emily raised the relevant point that …, he didn’t mention that ….. As a result, ….
While I appreciate the points mentioned by James and Emily, I think that ……………….
Remember that …, so …. Some people may feel that …., but I think …….. .