English Reading Comprehension

How many arguments did the new student offer to counter the geography master's routine argument?

Directions: Read the passage and answer the given question.

Returning home after a decade-and-half abroad, our ge­ography master remained incurably addicted to foreign ways and ideas for years after landing here. He would forever stick to his theory of Africans suffering from a curse inflicted on them by the Almighty God for some heinous sins committed centuries ago. He would, in support of this theory ask listen­ers, “Why would our mosquito inflict deadly malaria on us whereas the British mosquito does not bite? Why aren't there poisonous snakes in Britain whereas here most snakes are deadly? Why should the deadly sickle cell disease be peculiar to the black race?”

Of course, he would hardly wait for answers to these and similar questions before jumping to the same inevitable con­clusion. However, he met his match one day when a new student joined the class and heard the litany we were used to. The new boy calmly said. "Sir, I happened to know a few white men who suffer from the sickle cell disease: some are Italians and some are Spanish. The mosquito is equally deadly in India, South East Asian countries and South America. The United States and some other South American countries have their deadly snakes. And, sir, I know many white folks; some of them British, who would prefer our brilliant sunshine to their horribly cold winter." And he sat down.

I had never, before that day, seen our master so con­sumed with anger. He directed a burning look at the poor boy who had no answer to this new battle. Without as much as saying a single word, the master stalked out of the classroom. Needless to say, our anger was turned on the new boy, who had decided to rock the boat without taking the time to sound the water. A delegation was sent to the master to apologise to him. He was appeased. But we all noticed something rather unusual thereafter; never again did he dwell on the issue of Africans being the accursed people.

The unshakable serenity of the Hunza people is possibly attributable to

Directions: Read the passage and answer the given question.

The earthly paradises of Bali and of the South Sea Islands, and the gentle, non-acquisitive civilization of Burma have been aptly described and romanticized. One can add to them the Nicobar Islands, where a small population lives happily on a very low cultural level. But perhaps the most remarkable and the least known of these earthly paradises is the small kingdom of Hunza in the Himalayas, which was recently visited and enthusiastically described by the journalist, Noel Barber (Daily Mail, 5, 6, 8 June 1962).

A fair-skinned population of 18,000,  live in a fertile and almost inaccessible valley not far from the Sinkiang border, 8,000 feet up. A legend has it that they are the descendants of three deserters from the army of Alexander the Great, who settled here with Persian wives - which make one inclined to believe that pacifism may be hereditary, because these people had no war in 2,000 years. They have no money, no crime, and no diseases, they rarely die before ninety. Their psychosomatic control is almost unbelievable, childbirth is painless and toothache, a joke. They keep their numbers stationary without contraceptives, and without abortion, but by sheer abstinence, though Noel Barber saw the new born son of a chuckling father aged eighty-nine. Their diet, which consists mostly of apricots and raw vegetables, may have something to do with their unshakeable serenity. It makes one gasp with surprise that human nature can be like this. One is reminded of Huxley's Island, but unlike the Palanese, the Hunza people have no art, only serenity.

Which word in the passage can replace the expression 'a sudden intake of breath'?

Directions: Read the passage and answer the given question.

The earthly paradises of Bali and of the South Sea Islands, and the gentle, non-acquisitive civilization of Burma have been aptly described and romanticized. One can add to them the Nicobar Islands, where a small population lives happily on a very low cultural level. But perhaps the most remarkable and the least known of these earthly paradises is the small kingdom of Hunza in the Himalayas, which was recently visited and enthusiastically described by the journalist, Noel Barber (Daily Mail, 5, 6, 8 June 1962).

A fair-skinned population of 18,000,  live in a fertile and almost inaccessible valley not far from the Sinkiang border, 8,000 feet up. A legend has it that they are the descendants of three deserters from the army of Alexander the Great, who settled here with Persian wives - which make one inclined to believe that pacifism may be hereditary, because these people had no war in 2,000 years. They have no money, no crime, and no diseases, they rarely die before ninety. Their psychosomatic control is almost unbelievable, childbirth is painless and toothache, a joke. They keep their numbers stationary without contraceptives, and without abortion, but by sheer abstinence, though Noel Barber saw the new born son of a chuckling father aged eighty-nine. Their diet, which consists mostly of apricots and raw vegetables, may have something to do with their unshakeable serenity. It makes one gasp with surprise that human nature can be like this. One is reminded of Huxley's Island, but unlike the Palanese, the Hunza people have no art, only serenity.

The word in the passage that means ‘in body form' is _______.

Directions: Read the passage and answer the given question.

The great white shark is at the top of the marine food chain. In the shark family, it is the king that will eat anything, even other sharks. But as it gets older, bigger and slower, it develops a preference for seals, penguins and carrion - especially dead whales.

In locating their food, most sharks use all their senses including excellent vision. Their sense of smell is incredible and their ears are aided by pressure-sensitive cells along each side of their body. Nothing escapes this eavesdropping system, which is attuned to vibrations in the water. Sharks also have a sixth sense which enables them to detect the weak electrical fields emanating from the beating heart or the muscles of a potential prey.

The white shark's most fearsome assets are its huge head, its black eyes, and its razor-sharp, serrated teeth. The circulatory system of the white shark is different from that of most other sharks. Its blood temperature is about three to five degrees Celsius above water temperature. This speeds up digestion and adds to its strength and endurance.

It is known that the white shark spits out its wounded prey after an initial, powerful bite. Then it waits for the victim to die before eating it. Why does it use this bite-and­ spit strategy? Experts speculate that this is because of its eye. Unlike other sharks, the white shark has no eyelid like membrane to protect its eyes. Rather, it rotates them in their­ sockets when a collision is imminent. At the moment of impact, the eye is exposed, perhaps to the flaying, claws of a seal. "Therefore for the white shark a quick mortal strike and release is common behaviour.”

The public image of sharks has been greatly coloured by the novel Jaws which was turned into a popular movie. Overnight the white shark became evil incarnate. However, it is not a demon craving human flesh. The smell of blood does not drive it into a feeding frenzy as it does certain other sharks. Nevertheless it is the dangerous animal that should be treated with caution and respect.

The word in the passage that means ‘unbelievable' is _______.

Directions: Read the passage and answer the given question.

The great white shark is at the top of the marine food chain. In the shark family, it is the king that will eat anything, even other sharks. But as it gets older, bigger and slower, it develops a preference for seals, penguins and carrion - especially dead whales.

In locating their food, most sharks use all their senses including excellent vision. Their sense of smell is incredible and their ears are aided by pressure-sensitive cells along each side of their body. Nothing escapes this eavesdropping system, which is attuned to vibrations in the water. Sharks also have a sixth sense which enables them to detect the weak electrical fields emanating from the beating heart or the muscles of a potential prey.

The white shark's most fearsome assets are its huge head, its black eyes, and its razor-sharp, serrated teeth. The circulatory system of the white shark is different from that of most other sharks. Its blood temperature is about three to five degrees Celsius above water temperature. This speeds up digestion and adds to its strength and endurance.

It is known that the white shark spits out its wounded prey after an initial, powerful bite. Then it waits for the victim to die before eating it. Why does it use this bite-and­ spit strategy? Experts speculate that this is because of its eye. Unlike other sharks, the white shark has no eyelid like membrane to protect its eyes. Rather, it rotates them in their­ sockets when a collision is imminent. At the moment of impact, the eye is exposed, perhaps to the flaying, claws of a seal. "Therefore for the white shark a quick mortal strike and release is common behaviour.”

The public image of sharks has been greatly coloured by the novel Jaws which was turned into a popular movie. Overnight the white shark became evil incarnate. However, it is not a demon craving human flesh. The smell of blood does not drive it into a feeding frenzy as it does certain other sharks. Nevertheless it is the dangerous animal that should be treated with caution and respect.

The students of the class got annoyed with the new boy because

Directions: Read the passage and answer the given question.

Returning home after a decade-and-half abroad, our ge­ography master remained incurably addicted to foreign ways and ideas for years after landing here. He would forever stick to his theory of Africans suffering from a curse inflicted on them by the Almighty God for some heinous sins committed centuries ago. He would, in support of this theory ask listen­ers, “Why would our mosquito inflict deadly malaria on us whereas the British mosquito does not bite? Why aren't there poisonous snakes in Britain whereas here most snakes are deadly? Why should the deadly sickle cell disease be peculiar to the black race?”

Of course, he would hardly wait for answers to these and similar questions before jumping to the same inevitable con­clusion. However, he met his match one day when a new student joined the class and heard the litany we were used to. The new boy calmly said. "Sir, I happened to know a few white men who suffer from the sickle cell disease: some are Italians and some are Spanish. The mosquito is equally deadly in India, South East Asian countries and South America. The United States and some other South American countries have their deadly snakes. And, sir, I know many white folks; some of them British, who would prefer our brilliant sunshine to their horribly cold winter." And he sat down.

I had never, before that day, seen our master so con­sumed with anger. He directed a burning look at the poor boy who had no answer to this new battle. Without as much as saying a single word, the master stalked out of the classroom. Needless to say, our anger was turned on the new boy, who had decided to rock the boat without taking the time to sound the water. A delegation was sent to the master to apologise to him. He was appeased. But we all noticed something rather unusual thereafter; never again did he dwell on the issue of Africans being the accursed people.

The major difference between the kingdom of Hunza and the other earthly paradises described in the passage is that

Directions: Read the passage and answer the given question.

The earthly paradises of Bali and of the South Sea Islands, and the gentle, non-acquisitive civilization of Burma have been aptly described and romanticized. One can add to them the Nicobar Islands, where a small population lives happily on a very low cultural level. But perhaps the most remarkable and the least known of these earthly paradises is the small kingdom of Hunza in the Himalayas, which was recently visited and enthusiastically described by the journalist, Noel Barber (Daily Mail, 5, 6, 8 June 1962).

A fair-skinned population of 18,000,  live in a fertile and almost inaccessible valley not far from the Sinkiang border, 8,000 feet up. A legend has it that they are the descendants of three deserters from the army of Alexander the Great, who settled here with Persian wives - which make one inclined to believe that pacifism may be hereditary, because these people had no war in 2,000 years. They have no money, no crime, and no diseases, they rarely die before ninety. Their psychosomatic control is almost unbelievable, childbirth is painless and toothache, a joke. They keep their numbers stationary without contraceptives, and without abortion, but by sheer abstinence, though Noel Barber saw the new born son of a chuckling father aged eighty-nine. Their diet, which consists mostly of apricots and raw vegetables, may have something to do with their unshakeable serenity. It makes one gasp with surprise that human nature can be like this. One is reminded of Huxley's Island, but unlike the Palanese, the Hunza people have no art, only serenity.

Which of the following is not an argument that the geography master used to substantiate his theory?

Directions: Read the passage and answer the given question.

Returning home after a decade-and-half abroad, our ge­ography master remained incurably addicted to foreign ways and ideas for years after landing here. He would forever stick to his theory of Africans suffering from a curse inflicted on them by the Almighty God for some heinous sins committed centuries ago. He would, in support of this theory ask listen­ers, “Why would our mosquito inflict deadly malaria on us whereas the British mosquito does not bite? Why aren't there poisonous snakes in Britain whereas here most snakes are deadly? Why should the deadly sickle cell disease be peculiar to the black race?”

Of course, he would hardly wait for answers to these and similar questions before jumping to the same inevitable con­clusion. However, he met his match one day when a new student joined the class and heard the litany we were used to. The new boy calmly said. "Sir, I happened to know a few white men who suffer from the sickle cell disease: some are Italians and some are Spanish. The mosquito is equally deadly in India, South East Asian countries and South America. The United States and some other South American countries have their deadly snakes. And, sir, I know many white folks; some of them British, who would prefer our brilliant sunshine to their horribly cold winter." And he sat down.

I had never, before that day, seen our master so con­sumed with anger. He directed a burning look at the poor boy who had no answer to this new battle. Without as much as saying a single word, the master stalked out of the classroom. Needless to say, our anger was turned on the new boy, who had decided to rock the boat without taking the time to sound the water. A delegation was sent to the master to apologise to him. He was appeased. But we all noticed something rather unusual thereafter; never again did he dwell on the issue of Africans being the accursed people.

What does the author say about the complexion of Hunza population?

Directions: Read the passage and answer the given question.

The earthly paradises of Bali and of the South Sea Islands, and the gentle, non-acquisitive civilization of Burma have been aptly described and romanticized. One can add to them the Nicobar Islands, where a small population lives happily on a very low cultural level. But perhaps the most remarkable and the least known of these earthly paradises is the small kingdom of Hunza in the Himalayas, which was recently visited and enthusiastically described by the journalist, Noel Barber (Daily Mail, 5, 6, 8 June 1962).

A fair-skinned population of 18,000,  live in a fertile and almost inaccessible valley not far from the Sinkiang border, 8,000 feet up. A legend has it that they are the descendants of three deserters from the army of Alexander the Great, who settled here with Persian wives - which make one inclined to believe that pacifism may be hereditary, because these people had no war in 2,000 years. They have no money, no crime, and no diseases, they rarely die before ninety. Their psychosomatic control is almost unbelievable, childbirth is painless and toothache, a joke. They keep their numbers stationary without contraceptives, and without abortion, but by sheer abstinence, though Noel Barber saw the new born son of a chuckling father aged eighty-nine. Their diet, which consists mostly of apricots and raw vegetables, may have something to do with their unshakeable serenity. It makes one gasp with surprise that human nature can be like this. One is reminded of Huxley's Island, but unlike the Palanese, the Hunza people have no art, only serenity.

The geography master developed a special affinity to foreign ways and ideas because

Directions: Read the passage and answer the given question.

Returning home after a decade-and-half abroad, our ge­ography master remained incurably addicted to foreign ways and ideas for years after landing here. He would forever stick to his theory of Africans suffering from a curse inflicted on them by the Almighty God for some heinous sins committed centuries ago. He would, in support of this theory ask listen­ers, “Why would our mosquito inflict deadly malaria on us whereas the British mosquito does not bite? Why aren't there poisonous snakes in Britain whereas here most snakes are deadly? Why should the deadly sickle cell disease be peculiar to the black race?”

Of course, he would hardly wait for answers to these and similar questions before jumping to the same inevitable con­clusion. However, he met his match one day when a new student joined the class and heard the litany we were used to. The new boy calmly said. "Sir, I happened to know a few white men who suffer from the sickle cell disease: some are Italians and some are Spanish. The mosquito is equally deadly in India, South East Asian countries and South America. The United States and some other South American countries have their deadly snakes. And, sir, I know many white folks; some of them British, who would prefer our brilliant sunshine to their horribly cold winter." And he sat down.

I had never, before that day, seen our master so con­sumed with anger. He directed a burning look at the poor boy who had no answer to this new battle. Without as much as saying a single word, the master stalked out of the classroom. Needless to say, our anger was turned on the new boy, who had decided to rock the boat without taking the time to sound the water. A delegation was sent to the master to apologise to him. He was appeased. But we all noticed something rather unusual thereafter; never again did he dwell on the issue of Africans being the accursed people.

The word in the passage that can replace the expression 'cruel and wicked' is

Directions: Read the passage and answer the given question.

Returning home after a decade-and-half abroad, our ge­ography master remained incurably addicted to foreign ways and ideas for years after landing here. He would forever stick to his theory of Africans suffering from a curse inflicted on them by the Almighty God for some heinous sins committed centuries ago. He would, in support of this theory ask listen­ers, “Why would our mosquito inflict deadly malaria on us whereas the British mosquito does not bite? Why aren't there poisonous snakes in Britain whereas here most snakes are deadly? Why should the deadly sickle cell disease be peculiar to the black race?”

Of course, he would hardly wait for answers to these and similar questions before jumping to the same inevitable con­clusion. However, he met his match one day when a new student joined the class and heard the litany we were used to. The new boy calmly said. "Sir, I happened to know a few white men who suffer from the sickle cell disease: some are Italians and some are Spanish. The mosquito is equally deadly in India, South East Asian countries and South America. The United States and some other South American countries have their deadly snakes. And, sir, I know many white folks; some of them British, who would prefer our brilliant sunshine to their horribly cold winter." And he sat down.

I had never, before that day, seen our master so con­sumed with anger. He directed a burning look at the poor boy who had no answer to this new battle. Without as much as saying a single word, the master stalked out of the classroom. Needless to say, our anger was turned on the new boy, who had decided to rock the boat without taking the time to sound the water. A delegation was sent to the master to apologise to him. He was appeased. But we all noticed something rather unusual thereafter; never again did he dwell on the issue of Africans being the accursed people.

Which of these can be compared to the human genome after the new finding?

Directions: Answer the given question based on the following passage:

Junk. Barren. Non-functioning. Dark matter. That’s how scientists had described the 98% of human genome that lies between our 21,000 genes, ever since our DNA was first sequenced about a decade ago. The disappointment in those descriptors was intentional and palpable.
It had been believed that the human genome — the underpinnings of the blueprint for the talking, empire-building, socially evolved species that we are — would be stuffed with sophisticated genes, coding for critical proteins of unparalleled complexity. But when all was said and done, and the Human Genome Project finally determined the entire sequence of our DNA in 2001, researchers found that the 3 billion base pairs that comprised our mere 21,000 genes made up a paltry 2% of the entire genome. The rest, geneticists acknowledged with unconcealed embarrassment, was an apparent biological wasteland.
But it turns out they were wrong. In an impressive series of more than 30 papers published in several journals, including Nature, Genome Research, Genome Biology, Science and Cell, scientists now report that these vast stretches of seeming “junk” DNA are actually the seat of crucial gene-controlling activity — changes that contribute to hundreds of common diseases. The new data come from the Encyclopaedia of DNA Elements project, or ENCODE, a $123 million endeavor begun by the National Human Genome Research Institute (NHGRI) in 2003, which includes 442 scientists in 32 labs around the world.
ENCODE has revealed that some 80% of the human genome is biochemically active. “What is remarkable is how much of the genome is doing at least something. It has changed my perception of the genome,” says Ewan Birney, ENCODE’s lead analysis coordinator from the European Bioinformatics Institute.
Rather than being inert, the portions of DNA that do not code for genes contain about 4 million so-called gene switches, transcription factors that control when our genes turn on and off and how much protein they make, not only affecting all the cells and organs in our body, but doing so at different points in our lifetime. Somewhere amidst that 80% of DNA, for example, lie the instructions that coax an uncommitted cell in a growing embryo to form a brain neuron, or direct a cell in the pancreas to churn out insulin after a meal, or guide a skin cell to bud off and replace a predecessor that has sloughed off.
“What we learned from ENCODE is how complicated the human genome is, and the incredible choreography that is going on with the immense number of switches that are choreographing how genes are used,” Eric Green, director of NHGRI, told reporters during a teleconference discussing the findings. “We are starting to answer fundamental questions like what are the working parts of the human genome, parts list of the human genome and what those parts do.”

Which of the following best describes the purpose of the author in the passage?

Directions: Answer the given question based on the following passage:

Junk. Barren. Non-functioning. Dark matter. That’s how scientists had described the 98% of human genome that lies between our 21,000 genes, ever since our DNA was first sequenced about a decade ago. The disappointment in those descriptors was intentional and palpable.
It had been believed that the human genome — the underpinnings of the blueprint for the talking, empire-building, socially evolved species that we are — would be stuffed with sophisticated genes, coding for critical proteins of unparalleled complexity. But when all was said and done, and the Human Genome Project finally determined the entire sequence of our DNA in 2001, researchers found that the 3 billion base pairs that comprised our mere 21,000 genes made up a paltry 2% of the entire genome. The rest, geneticists acknowledged with unconcealed embarrassment, was an apparent biological wasteland.
But it turns out they were wrong. In an impressive series of more than 30 papers published in several journals, including Nature, Genome Research, Genome Biology, Science and Cell, scientists now report that these vast stretches of seeming “junk” DNA are actually the seat of crucial gene-controlling activity — changes that contribute to hundreds of common diseases. The new data come from the Encyclopaedia of DNA Elements project, or ENCODE, a $123 million endeavor begun by the National Human Genome Research Institute (NHGRI) in 2003, which includes 442 scientists in 32 labs around the world.
ENCODE has revealed that some 80% of the human genome is biochemically active. “What is remarkable is how much of the genome is doing at least something. It has changed my perception of the genome,” says Ewan Birney, ENCODE’s lead analysis coordinator from the European Bioinformatics Institute.
Rather than being inert, the portions of DNA that do not code for genes contain about 4 million so-called gene switches, transcription factors that control when our genes turn on and off and how much protein they make, not only affecting all the cells and organs in our body, but doing so at different points in our lifetime. Somewhere amidst that 80% of DNA, for example, lie the instructions that coax an uncommitted cell in a growing embryo to form a brain neuron, or direct a cell in the pancreas to churn out insulin after a meal, or guide a skin cell to bud off and replace a predecessor that has sloughed off.
“What we learned from ENCODE is how complicated the human genome is, and the incredible choreography that is going on with the immense number of switches that are choreographing how genes are used,” Eric Green, director of NHGRI, told reporters during a teleconference discussing the findings. “We are starting to answer fundamental questions like what are the working parts of the human genome, parts list of the human genome and what those parts do.”

Which of these is true according to the contents of the passage?

Directions: Answer the given question based on the following passage:

Women have to get their reproducing done early. The menopause curtails it, and even before that a woman’s fertility falls significantly over the years. Men—those who can find willing partners, at least—do not suffer in quite the same way, as many stories of celebrity elder fathers testify. But perhaps such ageing Lotharios should think twice, for evidence is accumulating that their offspring are at greater-than-average risk of genetic disease.
The latest study to this effect has just been published in Nature by Kari Stefansson and his colleagues at deCODE Genetics, a genetic-analysis company based in Reykjavik that was founded to take advantage of Iceland’s excellent medical records and its unique genealogical history. Recent immigrants apart, the relationship of almost everybody on the island to everybody else is known back as far as the first census, in 1703. In many cases it is known back to the first human settlement of the island, in 874.
Dr Stefansson’s study does not reach as far back as that. He and his colleagues examined 78 trios of father, mother and child who are all still alive. In some cases they looked at grandchildren as well. Their goal was to examine the number of new mutations—traits not found in the normal body cells of either parent—in children.
The average answer is about 63. That number, however, varies widely—and the main factor involved in this variation is the age of the father. Mothers transmitted an average of 14 mutations to their children, regardless of age. Fathers showed a much wider range: 20-year-olds passed on an average of 29 mutations; 30-year-olds (the average age of fatherhood in Dr Stefansson’s sample) passed on 49; and 40-year-olds passed 69.
That it is the father, rather than the mother, who causes this effect is probably because a woman’s eggs are created early on, when she is still in her mother’s womb, and are then put into what is, in effect, physiological deep-freeze until they are required for ovulation. Sperm, by contrast, are made continuously throughout life, and each division of their precursor cells brings risk of a misinterpretation of the DNA, and thus a mutation.
Dr Stefansson’s work adds to an existing body of research on the effect of paternal age. Previous studies have linked older fathers with higher rates of schizophrenia and autism in their offspring. In April three teams of researchers identified specific mutations that increase the chance of autism; all three observed that the risk of such mutations in a child rose with his father’s age at conception. But Dr Stefansson and his team are the first to measure the impact of older fathers so precisely.
Modern genomics made their task easier. After sequencing the genomes of each of the people involved, tallying the new mutations in the children was simply a matter of comparing the sequences of the parents with those of their offspring. Though both mother and father contribute to a child’s DNA, their contributions come in large, identifiable blocks. If a mutation is seen, its parentage is thus obvious.
There is, of course, the question of how much this matters, for most mutations have little effect—and a rare few, the stuff of evolution, are actually beneficial. According to Alexey Kondrashov of the University of Michigan, an expert on the matter who wrote an article in Nature to accompany Dr Stefansson’s study, about 10% of mutations are damaging. This means that for the average baby, six of Dr Stefansson’s 63 mutations are probably up to no good.
In Iceland, the average age of fathers at conception has risen from 28 in 1980 to 33 in 2011. Over the same period Dr Stefansson estimates that the number of new mutations in Iceland’s newborns jumped by more than 17%.

Which of these options accurately encapsulates the essence of the passage?

Directions: Answer the given question based on the following passage:

Junk. Barren. Non-functioning. Dark matter. That’s how scientists had described the 98% of human genome that lies between our 21,000 genes, ever since our DNA was first sequenced about a decade ago. The disappointment in those descriptors was intentional and palpable.
It had been believed that the human genome — the underpinnings of the blueprint for the talking, empire-building, socially evolved species that we are — would be stuffed with sophisticated genes, coding for critical proteins of unparalleled complexity. But when all was said and done, and the Human Genome Project finally determined the entire sequence of our DNA in 2001, researchers found that the 3 billion base pairs that comprised our mere 21,000 genes made up a paltry 2% of the entire genome. The rest, geneticists acknowledged with unconcealed embarrassment, was an apparent biological wasteland.
But it turns out they were wrong. In an impressive series of more than 30 papers published in several journals, including Nature, Genome Research, Genome Biology, Science and Cell, scientists now report that these vast stretches of seeming “junk” DNA are actually the seat of crucial gene-controlling activity — changes that contribute to hundreds of common diseases. The new data come from the Encyclopaedia of DNA Elements project, or ENCODE, a $123 million endeavor begun by the National Human Genome Research Institute (NHGRI) in 2003, which includes 442 scientists in 32 labs around the world.
ENCODE has revealed that some 80% of the human genome is biochemically active. “What is remarkable is how much of the genome is doing at least something. It has changed my perception of the genome,” says Ewan Birney, ENCODE’s lead analysis coordinator from the European Bioinformatics Institute.
Rather than being inert, the portions of DNA that do not code for genes contain about 4 million so-called gene switches, transcription factors that control when our genes turn on and off and how much protein they make, not only affecting all the cells and organs in our body, but doing so at different points in our lifetime. Somewhere amidst that 80% of DNA, for example, lie the instructions that coax an uncommitted cell in a growing embryo to form a brain neuron, or direct a cell in the pancreas to churn out insulin after a meal, or guide a skin cell to bud off and replace a predecessor that has sloughed off.
“What we learned from ENCODE is how complicated the human genome is, and the incredible choreography that is going on with the immense number of switches that are choreographing how genes are used,” Eric Green, director of NHGRI, told reporters during a teleconference discussing the findings. “We are starting to answer fundamental questions like what are the working parts of the human genome, parts list of the human genome and what those parts do.”