新東方網>英語>英語學習>語法詞彙>流行語>正文
英文閱讀：雞生蛋，蛋生雞？
2008-04-28 17:11
來源：中國日報網站
作者：
關於這個問題的討論似乎是經久不衰，可答案又不是那麼容易得出的。那麼，咱們就接著討論討論吧。
This question appears regularly in the question file, so let's take a shot at it.
In nature, living things evolve through changes in their DNA. In an animal like a chicken, DNA from a male sperm cell and a female ovum(卵) meet and combine to form a zygote(受精卵) -- the first cell of a new baby chicken. This first cell divides innumerable times to form all of the cells of the complete animal. In any animal, every cell contains exactly the same DNA, and that DNA comes from the zygote.
Chickens evolved from non-chickens through small changes caused by the mixing of male and female DNA or by mutations(突變) to the DNA that produced the zygote. These changes and mutations only have an effect at the point where a new zygote is created. That is, two non-chickens mated and the DNA in their new zygote contained the mutation(s) that produced the first true chicken. That one zygote cell divided to produce the first true chicken.
Prior to that first true chicken zygote, there were only non-chickens. The zygote cell is the only place where DNA mutations could produce a new animal, and the zygote cell is housed in the chicken's egg. So, the egg must have come first.
名稱名稱
微信掃碼關注"新東方網"服務號
回復""立刻獲取！
版權及免責聲明
① 凡本網註明"稿件來源：新東方"的所有文字、圖片和音視頻稿件，版權均屬新東方教育科技集團（含本網和新東方網） 所有，任何媒體、網站或個人未經本網協議授權不得轉載、連結、轉貼或以其他任何方式複製、發表。已經本網協議授權的媒體、網站，在下載使用時必須註明"稿件來源：新東方"，違者本網將依法追究法律責任。
② 本網未註明"稿件來源：新東方"的文/圖等稿件均為轉載稿，本網轉載僅基於傳遞更多信息之目的，並不意味著贊同轉載稿的觀點或證實其內容的真實性。如其他媒體、網站或個人從本網下載使用，必須保留本網註明的"稿件來源"，並自負版權等法律責任。如擅自篡改為"稿件來源：新東方"，本網將依法追究法律責任。
③ 如本網轉載稿涉及版權等問題，請作者見稿後在兩周內速來電與新東方網聯繫，電話：010-60908555。