영어 모의고사 (자동 편성)

Bacteria have been cutting up invading viral DNA for billions of years, long before any scientist ①thought to borrow the trick for use in a laboratory. The CRISPR-Cas9 system, as it is now known, relies on a short guide RNA that matches a specific DNA sequence, ②lead a scissor-like enzyme called Cas9 directly to that exact location in the genome. Once Cas9 arrives at the target site, it slices both strands of the DNA helix, and the cell's own repair machinery rushes in ③to mend the cut, often introducing a small change in the process. By supplying the cell with a template during this repair step, scientists can direct that machinery ④to insert a specific new sequence rather than merely disabling the original gene. What once required years of painstaking work to alter a single gene can now, with a properly designed guide RNA, ⑤be accomplished within days, a shift in speed that has reshaped nearly every corner of biological research.

A cluster of neurons smaller than a pea can now spontaneously ①organizing itself into layered structures that mimic, in miniature, the architecture of a developing human brain. Grown from stem cells coaxed to follow the same developmental cues that guide an embryo, these brain organoids have begun ②firing electrical signals in patterns that faintly resemble the activity recorded in an infant's brain. For researchers studying disorders such as autism or schizophrenia, this offers something long unavailable: a living model of human brain development that can be ③observed and manipulated directly, without ever touching an actual patient. Because organoids lack sensory organs, a body, or any connection to the outside world, most neuroscientists argue that the structures cannot generate anything ④resembling subjective experience, however brain-like their electrical activity may appear. Even so, the pace at which these organoids are growing more complex has convinced some ethicists that the field would benefit from ⑤establishing clear boundaries now, before the science outruns the conversation about what it means.

A biosensor works by pairing a biological component, such as an enzyme or antibody, with an electronic device that ①convert a biological reaction into a signal a computer can read. When the target molecule, whether glucose in blood or a trace of a pathogen, ②binds to the biological component, it triggers a small measurable change that the device translates into a readable number. This design has already transformed diabetes management, ③letting patients monitor blood sugar continuously through a small sensor worn under the skin rather than pricking a finger several times a day. Engineers are now racing to extend the same principle ④to detect subtler targets, from cancer cells circulating in the bloodstream to trace contaminants in drinking water. The central challenge is not detecting the target but doing so reliably outside a controlled laboratory, since a sensor that performs well on a clean lab bench can behave erratically once ⑤exposed to a real body or a real river.

A cotton plant that manufactures its own insecticide sounds like science fiction, yet it has been growing in fields around the world for ①decades. Scientists achieved this by isolating a gene from a soil bacterium that produces a protein ②toxic to specific insect pests but ⑤harmless to humans, then inserting that gene into the plant's own genome so that every cell manufactures the protective protein. Other genetically modified crops carry a gene that allows them to survive direct exposure to a particular herbicide, letting farmers spray a field to kill weeds without harming the crop growing among them. Supporters point to yield increases and ③reduced pesticide spraying documented across millions of hectares, while critics worry about weeds and insects evolving resistance to these built-in defenses over time, much as bacteria evolve resistance to antibiotics. Regulatory agencies in most countries now require ④minimal testing before a genetically modified crop reaches the market, evaluating everything from its nutritional content to its potential effects on nearby ecosystems.

Two patients diagnosed with the same disease and prescribed the same medication can respond in strikingly different ways, one recovering quickly while the other experiences little benefit or even harmful side effects. Precision medicine starts from the observation that this variation often traces back to differences buried in each patient's genome, differences that determine how efficiently a body absorbs, breaks down, or responds to a given drug. _______________. This approach has proven especially valuable in cancer treatment, where tumors from two patients with the same diagnosis may carry entirely different genetic mutations that respond to entirely different drugs. Widespread adoption still faces real obstacles, since genetic sequencing remains expensive in many regions and few doctors have been trained to interpret the flood of genetic data such tests now produce.

A cricket contains, gram for gram, roughly as much protein as beef, yet requires a small fraction of the land, water, and feed needed to raise cattle. This efficiency has drawn growing attention from researchers looking for ways to feed a global population that continues to climb while arable land remains essentially fixed. Insects also convert feed into body mass with remarkable efficiency, since they are cold-blooded and therefore spend far less energy regulating body temperature than a cow or pig must. _______________. Food companies have responded by grinding insects into a flour that disappears into protein bars, pasta, and baked goods, letting consumers benefit from the nutrition without ever having to look an insect in the eye.

The immune system produces an almost limitless variety of antibodies, each shaped to latch onto one particular molecular target with remarkable specificity. Monoclonal antibody drugs harness this natural precision by cloning a single antibody-producing cell in the laboratory, generating an army of identical antibodies built to recognize one target, such as a protein on a cancer cell or a molecule driving an autoimmune disease. _______________. Manufacturing monoclonal antibodies remains far more complicated than producing a conventional small-molecule pill, since living cells must be cultivated in carefully controlled bioreactors for weeks before the antibody can be purified and prepared for use. This complexity keeps monoclonal antibody treatments considerably more expensive than most conventional drugs, a cost that continues to shape debates over pricing and access.

When a country physician named Edward Jenner noticed that milkmaids who had caught cowpox seemed immune to smallpox, he set in motion a medical revolution without fully understanding why it worked. (A) This method produced genuine successes, eventually eliminating smallpox worldwide and reducing diseases such as polio and measles, but each new vaccine still required years of laboratory work with no guarantee of success. (B) Advances in molecular biology eventually allowed researchers to isolate a single protein from a pathogen's surface, producing vaccines with fewer side effects, and the most recent shift toward delivering genetic instructions represents the latest chapter in this story. (C) For nearly two centuries afterward, vaccine development proceeded largely by trial and error, weakening or killing a pathogen and testing whether the resulting preparation could train the immune system without causing disease itself.

Even so, the shift has proven immensely practical, sidestepping the objection that halted so much earlier research. A single fertilized egg eventually gives rise to every cell type in the human body, from neurons to bone, a feat that has fascinated biologists for more than a century. ( ① ) Embryonic stem cells retain much of that original versatility, capable in principle of developing into almost any tissue, which is why researchers have long viewed them as a promising raw material for repairing damaged organs. ( ② ) Because harvesting these cells traditionally required destroying a human embryo, the research provoked ethical objections fierce enough to slow funding and legislation in several countries for years. ( ③ ) A breakthrough arrived when scientists discovered that ordinary adult skin cells could be reprogrammed, through the introduction of a handful of specific genes, into a state resembling embryonic versatility without ever touching an embryo. ( ④ ) These induced pluripotent cells, as they are now called, have not entirely erased the ethical debate. ( ⑤ ) They have opened a path for stem cell research that far more scientists and funding agencies are willing to support.

The cell then acts as a temporary factory, translating that instruction into an actual protein without ever altering the cell's permanent genetic code. For decades, most vaccines worked by injecting a weakened or inactivated version of a pathogen, coaxing the immune system into recognizing an enemy it had never truly fought. ( ① ) mRNA vaccines take a fundamentally different route, delivering only a short genetic instruction wrapped in a protective lipid capsule, one that tells the body's own cells how to manufacture a single harmless piece of a virus's outer surface protein. ( ② ) Once those cells display the fragment, the immune system learns to recognize it as foreign and builds a defense, without ever having encountered the actual pathogen. ( ③ ) Because the vaccine contains no live virus and cannot alter a cell's own DNA, developers can redesign the genetic instructions within weeks whenever a pathogen mutates. ( ④ ) This is far shorter than the years-long process required for traditional vaccines. ( ⑤ ) This speed, first proven on a global scale during a recent pandemic, has convinced many researchers that the same platform could eventually be adapted to fight diseases far beyond infectious illness, including certain cancers.