4-5翻譯

We have developed two ways to change the genetic traits of populations
We have used artificial selection to change the genetic characteristics of populations with similar genes. In this process, we select one or more desirable genetic traits in the population of a plant or animal, such as a type of wheat, fruit, or dog. Then we use selective breeding to end up with population of the species containing large numbers of individuals with the desired traits. Note that artificial selection involves crossbreeding between genetic varieties of the same species and thus is not a form of speciation.
Artificial selection has yield food crops with higher yield, cows that give more milk, tree that grow faster, and many different types of dogs and cats. But traditional crossbreeding is a slow process. Also ,it can combine traits only from species that are close to one another genetically.
Now scientists are using genetic engineering to speed up our ability to manipulate genes. Genetic engineering, or gene splicing, is the alteration of an organism’s genetic material, through adding, deleting, or changing segments of its DNA, to produce desirable traits or eliminate undesirable ones. It enables scientists to transfer genes between different species that would not interbreed in nature. For example, genes from a fish species can be put into a tomato plant to give it certain properties.
The result organisms are called genetically modified organisms or transgenic organisms. Compared to traditional crossbreeding, gene splicing take about half as much time to develop a new crop or animal variety. It also enables us to transfer genes from different type of species without breeding them – a process that both hold great promise and raises a number of legal, ethical, and environmental issues.
Scientists have used gene splicing to develop modified crop plants, new drug, pest-resistant plants, and animal that grow rapidly. They have also creates genetically engineered bacteria to extract minerals such as copper from their underground ores and to clean up spills of oil and other toxic pollutants.
Bioengineers have developed many beneficial genetically modified organisms : chickens that lay low-cholesterol eggs, wheat that thrives in drought conditions, bananas that don’t
Genetic engineers have also produced two mice, the Schwarzenegger mouse, which has muscle-building genes, and the marathon mouse, which never seems to tire. And they are in hot pursuit of a Methuselah mouse that can live much longer than a conventional mouse.
我們使用人為淘汰改變人口的基因特徵與相似的基因人口的基因特徵。 在這個過程，我們在植物或動物的人口選擇一個或更多中意的基因特徵，例如麥子、果子或者狗的類型。 然後我們使用有選擇性的飼養最終獲得包含很大數量的個體以期望特徵的種類的人口。 注意人為淘汰介入雜交育種在同一個種類的基因品種之間和因而不是物種形成的形式。 人為淘汰有出產量給更多牛奶的食用農作物與更高的出產量，快速地增長的母牛，樹和狗和貓的許多不同的類型。 但傳統雜交育種是一個緩慢的過程。 並且，它可能結合仅特徵從是緊挨互相基因上的種類。 現在科學家使用遺傳工程加速我們的能力操作基因。 遺傳工程或者基因接合，是有機體的基因的改變，通過增加，刪除或者它的脫氧核糖核酸的改變的段，導致中意的特徵或消滅不受歡迎的人一个。 它使科學家轉移基因不會混種本質上的區別種類之間。 例如，基因從魚種類可以被放入番茄給它某些物產。 結果有機體稱基因上修改過的有機體或transgenic有機體。 與傳統雜交育種，基因接合的作為比較大約半同樣多時間開發新的莊稼或動物品種。 它也使我們從種類的另外類型轉移基因，不用飼養他們-擁有巨大諾言的過程并且提出一定數量的法律，道德和環境問題。 科學家使用了基因接合開發迅速地增長的修改過的莊稼、新的藥物、蟲抗性植物和動物。 他們有也創造基因上設計的細菌從他們的地下礦石提取礦物例如銅和清掃油和其他毒性汙染物溢出。 Bioengineers開發了許多有利基因上修改過的有機體： 下低膽固醇蛋，麥子在天旱情況，香蕉興旺沒有基因工程師也生產了二隻老鼠、Schwarzenegger老鼠，有肌肉大廈基因和馬拉松老鼠，從未似乎疲倦的。 并且他們在比一隻常規老鼠能長期居住對一隻Methuselah老鼠的緊追不舍中。