Підготовка до здачі TOEFL. BACTERIA. QUESTIONS?

Сьогоднішній Reading — це яскравий приклад того, як треба вчитися розкодовувати текст, навіть, якщо ти ну зовсім не в темі. Тобі в тому допоможуть вже відомі слова, фрази і (звучить так розумно!) граматичні конструкції.

Give bacteria a bit of self-awareness and they can be smarter about producing biofuel.
That's the conclusion from researchers at the University of California, Berkeley, who report a genetic sensor that enables bacteria to adjust their gene expression in response to varying levels of key intermediates for making biodiesel. As a result, the microbes produced three times as much fuel. Such a sensor-regulator system could eventually make advanced biofuels cheaper and bring them a step closer to being an economically viable replacement to petroleum-based products.

One issue that has limited the amount of biofuels that a microbe makes is an imbalance of the different biological ingredients, or precursors, used to make the final fuel product. In a study published this week in Nature Biotechnology, Jay Keasling, professor of chemical engineering and bioengineering at UC Berkeley, and colleagues describe a biological sensor system that lets bacteria regulate genes in its biofuel-production pathways according to the amount of certain precursors in the cell.

The researchers augmented a previously reported strain of engineered E. coli that creates biodiesel from two biological building blocks—fatty acids and ethanol. Over the life cycle of that strain, one precursor can be produced at a higher level than another, an inefficient and sometimes harmful situation.

"The pathways weren't in balance," says Keasling. "The cells were wasting resources producing one precursor at a higher level than another." What's more, he says, biofuel production would sometimes consume too many fatty acids, which the bacteria need at certain stages of their life cycle, making the strain unstable.

Keasling and coworkers designed a microbe, using a naturally occurring sensor, that responds to the amounts of internal fatty acids and related molecules and tunes the activity of its pathways accordingly. When limited amounts of fatty acid are in the cell, the sensor-regulator molecules put the brakes on both the ethanol-producing pathway and the fatty acid-converting pathway. Conversely, when the bacteria contain higher levels of fatty acids, the brakes on these pathways are released.

The sensor-regulator system improves the engineered bacteria in two ways, says Keasling: the metabolic pathways are better balanced so that one precursor isn't overproduced relative to the other, and the modified bacteria are more stable because the biofuel production isn't robbing the cell of the ability to grow. This "self-awareness" increased the amount of biodiesel made by the bacteria to 28 percent of theoretical maximum, a threefold increase over the previously reported strain.  

Although the improvement is significant, biodiesel production is still too limited to bring the fuel into the mainstream. "There are many issues, including metabolic imbalances, that need to be solved to make biofuels a reality," said Keasling in an e-mail. For instance, expanding these largely experimental cultures to commercial scale—on the order of a million liters—will be a challenge.

While the genetic regulator will not be the only key to opening up the nascent biofuels field, it is an elegant strategy for improving yields, says James Liao, a biomolecular engineer at the University of California, Los Angeles. "The sensor-regulator system will be a very useful tool in the toolbox we currently have."

VOCABULARY

bacteria: singular bacterium

viable: able to be done, or worth doing

The present system is simply no longer viable.
commercially/economically/financially viable (=capable of producing a profit):

Hospitals plan to stop services that are not financially viable.
 

to augment: to increase the size, amount, or value of something

The team of editors was augmented by freelancers.
 

to tune: to develop or to train someone or something

Try to tune your ear to distinguish between the sounds.
 

a brake: an action or a situation that prevents something from developing or making progress

put a brake/the brakes on something:
The high level of debt put a brake on economic recovery.
release the brakes on smth: opposite to put the brakes on smth
 

to rob sb/ sth of smth: to take money or property illegally from a person or place, often using threats or violence

Daniel was robbed of his car, briefcase, and mobile phone.
 

threefold, adj: three times as much

a threefold increase in price
 

to bring sth into the mainstream

nascent: beginning or formed recently

nascent skills
 

yield, n. : an amount of something that is produced

And here are some tricky QUESTIONS:

1. What did the author mean by the following statement: 'Give bacteria a bit of self-awareness and they can be smarter about producing biofuel.'
A. Microbes are more intelligent at producing biofuel.
B. Bacteria need to be self conscious for producing biofuel.
C. Individual bacterium needs to liberate itself.
D. A scientific effort is needed to make bacteria more efficient at biofuel production.

2. The word 'precursor' refers to which of the following:
A. an ingredient for the recipe of biofuel.
B. an organiccompound that will be processed by bacteria.
C. a state in which engineered E.Coli exists.
D. a condition needed for engineered E.Coli to survive.

3. The "self-awereness"mentioned by the author refers to:
A. a sensor-regulator system and metabolic pathways;
B. better biofuel production;
C. production of fatty acids and ethanol plus stable bacterial growth;
D. the threefold biofuel production increase.

4. According to the author why is biodisel still too limited for mainstream production?
A. Because the bacterial cultures are hard to grow.
B. The engineered microbes still have many issues.
C. There are many problems including metabolic disharmony.
D. Because the genetic regulator is the only available "device" for increasing the efficiency of biofuel production.


SPEAKING: THE BIGGEST CHALLENGE IN YOUR LIFE
 

Так-так, чекаю твої "промови" розміром 30 секунд  на адресу [email protected].

Tell about the biggest challenge in your life. Use some specific examples and explain why it was a challenge.

LISTENING: SCHOOL KILLS CREATIVITY

TED.com. Чудове джерело для інформативного і надихаючого listening. Одним з таких радо з тобою поділюся: School kills creativity by Ken Robinson! Крім чудової британської англійської, цікаві думки і британський гумор :)

 
INDEPENDENT WRITING: QUESTIONS?
  
Одна з моїх улюблених стратегій в написанні essay, то питання. Так вже повелося, що я люблю задавати зустрічні питання:) Просто.. ніколи ж не знаєш, що в голові людини, що перевірятиме твою роботу.. Якою б вона об'єктивною не була. Тому мої питання часом просто мають на меті нагадати перевіряючому, що ми з ним не одного cultural background і в нас зовсім різні values in life. Ну, чи щось таке.

Говорячи про питальну стратегію, маю наголосити, що вона не має бути спробою втечі від теми — цього тобі не пробачать, якою б гарною англійською ти не володів.

Питальна стратегія далеко не найлегша, особливо, коли в тебе є часові обмеження.

Отож, questions

Мета: привернути увагу читача.

SIMPLE QUESTIONS

Ну отак от все коротко і просто, і здавалося б, навіщо присвячувати питанням пост. Перечитуючи ваші ессе, які я радо отримую на [email protected], помічаю, що не я одна люблю питання. Проблема: граматичне “оформлення” питань.

Ми вводимо питання в твір по-різному: directly or indirectly.
Directly: Why are museums so popular?
Indirectly: I wonder why museums are so popular.
Річ в тім, що в “непрямому” питанні є питальне слово, але порядок слів після нього такий, як в стверджувальному реченні:

N.B. не забуваємо, що в разі yes/no question ми використовуєм if or whether в якості питального слова.

Чекаю на ваші творіння з використанням питальної чи іншої стратегії на [email protected]. This week the task is: