In recent years,scientific and technological developments have drastically changed human life on our planet,as well as our views both of ourselves as individuals in society and of the universe as a whole.Perhaps one of the most profound developments of the 1970s was the discovery of recombinant DNA technology,which allows scientists to introduce genetic material(or genes)from one organism into another.
In its simple form,the technology requires the isolation of a piece of DNA,either directly from the DNA of the organism under study,or artificially synnthesized from an RNA template,by using a viral enzyme called reverse transcriptase.This piece of DNA is then ligated to a fragment of bacterial DNA which has the capacity to replicate itself independently.The recombinant molecule thus produced can be introduced into the common intestinal bacterium Escherishchia coli,which can be grown in very large amounts in synthetic media.Under proper conditions,the foreign gene will not only replicate in the bacteria,but also express itself,through the process of trascription and translation,to give rise to large amounts of the specific protein codd by the foreign gene.
The technology has already been successfully applied to production of several therapeutically important biomolecules,such as insulin,interferon and growth hormones.Many other important applications are under detailed investigation in laboratories throughout the world.
1.Recombinant DNA technology consists primarily of……….
a.producing several thrapeutically important biomolecules
b.giving rise to large amounts of protein
c.introducing genetic material from one organism into another
d.using a viral enzyme called reverse transcriptase
pembahasan:Paragraph 1,sentence 2,says that the technology”allows scientists to introduce genetic materil(or genes)from one organism into another.”The key word in this question is”primarily.”Choice(D) is a small part of the technology.Choice(A)is a result of the technology.Choice(B)is the function of the foreign gene and also involves only a part of the technology.
2.The word”profound”in line 4 is closest in meaning to…..
pembahasan:Substitute the answer choices for “profound” in the sentence.From the context,you can infer that recombinant DNA technology is incredible.The development is not “boring,”choice(B),or”secret,”choice(D).The technology may be” dangerous,”choice(C),but that is not the focus of this sentence.”profound”means”significant”in this use.
3.In line 8,the word”isolation”is closest in meaning to
pembahasan:Paragraph 1,sentence 5,tells us that Escherichia coli a bacterium into which the recombinant molecule can be introduced.It is not itself produced by DNA technology.
4.recombinant DNA technology has been used in the production of all the following biomolecules except
pembahasan:The word”artificially”means”not naturally,”or”synthetically.”
5.In line 10,”artificially”is closest in meaning to
pembahasan:In the sentence,a piece of DNA is being”ligated”to a fragment of bacterial DNA.The only answer choice that makes sense is(D).
6.The word”ligated”in line 12 is closest in meaning to
pembahasan:Sentence 6 states that”the foreign gene will not only replicate in the bacteria,but also express itself.”Thus choice(A)is the one choice that is not true.Choices(B),(C)and(D)are specifically mentioned in the passage.
7.In line 13,the word”fragment”is nearest in meaning to
pembahasan:The”fragment”in the sentence is some bacterial DNA.Choices(B)and(C)do not make sense,and it’s highly unlikely that scientists would be dealing with a “large piece”(D)of DNA.”particle”is the best answer choice.
8.The word”capacity”in line 13 is nearest in meaning to
pembahasan:The sentence states that bacterial DNA has the”capacity”to replicate itself independently.DNA doesn’t have”hormones,”choice(A),”technology,”choice(B),or”space,”choice(D).It does have the”ability”to replicate,however,so that is the best choice.
9.Expression of a gene in Escherichia coli requires
a.the viral enzyme reverse transcriptase
b.the processes of transcription and translation
c.production of insulin and other biomolecules
d.that the bacteria be grown in a synthetic media.
pembahasan:The last sentence of paragraph 1 states that the expression of a gene requires the processes of transcription and translation.Choice(D)is not true because,while the reading states that Escherichia coli may be produced in large amounts is synthetic media,it does not say that it requires synthetic media.
10.The term”recombinant”is used because
a.by ligation,a recombinant molecule is produced,which has the capacity of replication
b.the technique requires the combination of several types of technology
c.by ligation,a recombinant protein is produced;part of whole amino acids come from each different organism
d.Escherichia coli is a recombinant organism
pembahasan:Sentence 4 says,”This piece o DNA is then ligated to a fragment of bacterial DNA which has the capacity to replicate itself independently.”Sentence 5 continues,”he recombinant molecule thus produced……..”This means that two different molecules are ligated(joined)to produce”a recombinant molecule.”Choice(B)is not true,since,although several technologies are combined,the reading does not say that the technologies are recombined.Choice(C)is not true because recombination of molecules is at the level of DNA,and not at the level of their products,the proteins.Choice(D)is not true because escherichia coli is used to obtain expression of the recombinant molecule,but it is a”common intestinal bacterium,”and not a recombinant.
11.The word”replicate”in line 14 is closest in meaning to
pembahasan:The fact that the volcanoes on Mars are believed to be”dormant,”though some show signs of activity,should lead you to choose”inactive”as the synonym for”dormant”and the condition of most of the volcanoes.
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