IELTS Data Reading Passage 226 – DNA Computers
You should spend about 20 minutes on Questions 1-13 which are based on IELTS Data Reading Passage 226 – DNA Computers Reading Passage Below:-
DNA Computers
{A} From a modern chemist’s perspective, the structure of DNA in our genes is rather mundane. The molecule has well-known importance for life, but chemists often see only a uniform double helix with almost no functional behaviour on its own. It may come as a surprise, then, to learn that this molecule is the basis of a truly rich and strange research area that bridges synthetic chemistry, enzymology, structural nanotechnology, and computer science.
{B} Using this new science, scientists have constructed molecular versions of logic gates that can operate in water solutions. Our building these DNA-based computing modules is to develop nanoscopic machines that could exist in living organisms, sensing conditions and making decisions based on what they sense, then responding with actions such as releasing medicine or killing specific cells.
{C} Scientists have demonstrated some of the abilities of our DNA gates by building automata that play perfect games of tic-tac-toe. The human player adds solutions of DNA strands to signal his or her moves, and the DNA computer responds by lighting up the square it has chosen to take next. Any mistake by the human player will be punished with defeat. Although game playing is a long way from our ultimate goals, it is a good test of how readily the elementary molecular computing modules can be combined in plug-and-play fashion to perform complicated functions, just as the silicon-based gates in modern computers can be wired up to form the complex logic circuits that carry out everything that computers do for us today,
{D} Scientists planned to borrow an approach from electrical engineering and create a set of molecular modules, or primitives, that would perform elementary computing operations. In electrical engineering, the computing primitives are called logic gates, with intuitive names such as AND, OR, and NOT. These gates receive incoming electrical signals that represent the Os and ls of binary code and perform logic operations to produce outgoing electrical signals. For instance, an AND gate produces an output 1 only if its two incoming inputs are both 1. Modern-day computers have hundreds of millions of such logic gates connected into very complex circuits, like elaborate structures built out of just a few kinds of Lego blocks. Similarly, scientists hoped that our molecular modules could be mixed together into increasingly complex computing devices.
{E} Scientists did not aim, however, to compete with silicon-based computers. Instead, because someone had just finished a brief stint with a pharmaceutical company, related scientists settled on developing a system that could be useful for making “smart” therapeutic agents, such as drugs that could sense and analyze conditions in a patient and respond appropriately with no human intervention after being injected. For example, one such smart agent might monitor glucose levels in the blood and decide when to release insulin. Thus, our molecular logic gates had to be biocompatible.
{F} Such molecular modules could have innumerable functions. For instance, in diseases such as leukaemia, numerous subpopulations of white blood cells in the immune system display characteristic markers on their cell surfaces, depending on the cells’ lineage and their stage of development. Present-day therapies using antibodies eliminate large numbers of these subpopulations at once because they target only one of the surface markers. Such indiscriminate attacks can suppress the patient’s immune system by wiping out too many healthy cells, leading to serious complications and even death. Molecular modules capable of working together to sense and analyze multiple markers—including performing logical operations such as “markers A and either B or C are present, but D is absent” might be able to select the specific subpopulations of cells that are diseased and growing out of control and then eliminate only those cells..
{G} Another application of our modules could be in the analysis of DNA, looking for a large array of possible genetic mutations or identifying one of a wide variety of microbiological pathogens. Our most advanced tic-tac-toe-playing automaton combines 32 different short DNA sequences (oligonucleotides). That many logic gate inputs could analyze four billion possible combinations of oligonucleotides and partition them into thousands of patterns, each pattern being characteristic of certain pathogens or genotypes.
{H} Researchers reported logic gates based on synthetic molecules as long ago as the early 1990s. In 1993, for instance, A. Prasanna de Silva and his collaborators at Queen’s University Belfast made AND gates out of small organic molecules that would fluoresce only if both hydrogen ions (from acid) and sodium ions were bound to them. In 1997 J. Fraser Stoddart, now at Northwestern University, and his co-workers made exclusive OR” (XOR) gates, in which the molecules fluoresce in the presence of either, but not both, of the inputs (in this case, hydrogen ions and molecules called amines). These examples, however, were not biocompatible, because they required concentrations of acid and other compounds that would harm living cells.
{I} In the mid-1990s another researcher exploited DNA’s ability to store information in its sequence of bases—the molecules conventionally abbreviated as A, T, G, and C, which pair up to form the rungs connecting the two strands of the famous double-helix structure. Their techniques, however, were very different from the kind of system we envisaged, namely, one in which molecular logic gates floating in solution would process inputs and outputs in a fashion very analogous to the workings of silicon logic gates. Nevertheless, DNA clearly had a lot of potential for biocompatible computation, and a couple of other advances gave us the tools to invent our own brand of DNA logic gates.
{J} Special dye molecules attached to each end of the substrate strands enable laboratory workers to monitor the cleaving process. At one end of the substrate, the dye molecule is a “quencher,” which prevents the fluorescent marker dye at the other end from fluorescing as long as the strand remains intact, keeping the quencher close enough to be effective. After the strand is cut, its two pieces move apart and the marker dye molecule can fluoresce unhindered. As the work of the DNA enzymes progresses, cutting more and more strands, the solution gradually lights up with the marker dye’s fluorescent colour.
Questions 1-5
Do the following statements agree with the information given in Reading Passage?
In boxes 1-5 on your answer sheet, write
| TRUE | if the statement is True |
| FALSE | if the statement is false |
| NOT GIVEN | If the information is not given in the passage |
Question 1:- The application based on the structure of DNA molecules ranges from macro- realms to microscopic domains.
Question 2:- The modern computer-based on silicon gates also experienced a similar process from invention to application.
Question 3:- The original intention for researchers to study DNA computers was to surpass the traditional computers someday.
Question 4:- The research on DNA can also benefit from molecular modules which are invented based the exploration of the structure of DNA itself.
Question 5:- The application of DNA for biocompatible computation can be realized in the near future.
Questions 6-10
The reading Passage has seven paragraphs A-J.
Which paragraph contains the following information?
Write the correct letter A-J, in boxes 6-10on your answer sheet.
Question 6:- the therapeutic use to deal with glycometabolism
Question 7:- the main flaw for two teams of researchers’ contribution to molecular gates
Question 8:- given molecules for colouring specific processes
Question 9:- the link between DNA molecules and several odd research branches
Question 10:- the selective elimination of targeted cells
Questions 11-13
Complete the following summary of the paragraphs of Reading Passage, using no more than three words from the Reading Passage for each answer. Write your answers in boxes 11-13 on your answer sheet.
| A principle applied in ……….11………. can be used to produce new forms involving………12………. which are not based on numerous ………13……… linked with intricate electrical networks and expected to become more and more complicated computations. |
IELTS Data Reading Passage 226 – DNA Computers Answers
| 1 | TRUE | 8 | J |
| 2 | NOT GIVEN | 9 | A |
| 3 | FALSE | 10 | F |
| 4 | TRUE | 11 |
ELECTRICAL ENGINEERING
|
| 5 | NOT GIVEN | 12 | LOGIC GATES |
| 6 | E | 13 |
MOLECULAR MODULES
|
| 7 | H |