The Ghost In Your Genes - 5 基因外遗传现象

It showed that there was clearly more to inheritance than simply the coded sequence of DNA¹.

We then realized that we were dealing² with what is now known as genomic imprinting³. What genomic imprinting means is, in a nutshell, that genes⁵ have a memory of where they came from.

Something other than just the DNA was capable of moving between generations. It was a tantalizing⁶ glimpse into this unknown and unexpected world. A hidden layer acting⁷ on and able to directly control how our genes function. It meant that inheritance was not simply about which genes you inherited, but whether those genes were silenced, switched on or off.

And you can think of it as a, as a light switch. Switch on the gene⁴, the light is shining, the gene is active, makes, makes a cell do a certain thing. Or the light switch is off, everything is dark, that gene is off. The switches remain on or remain off, and that gives the cells their identity.

The activity of genes was being controlled by a switch--the attachment⁸ of a simple chemical which dictated⁹ whether the gene was switched on or off.

Whether those genes are turned on or off is called epigenetics.

Epigenetics, er, you know, up on the genes.

Not only is the sequence important for the DNA, which we've studied for a long time in the past few decades, but we now understand that in addition to that there is this overlying epigenetic phenomenon that allows the genes to get turned on or off.

Epigenetics could explain how a human could be created with less than 30,000 genes and why the Genome Project didn't provide all the answers.

Now if we actually put epigenetics on top of it, where makes it much more complicated on whether genes get activated¹⁰ and to a certain level and so forth¹¹. Then you have a complexity¹² that can start to explain biology much more effectively than the simple sequence of the DNA.

So clearly we have additional levels of complexity that we now need to understand that are beyond the DNA.

The next huge challenge for modern biology is to now decipher the epigenetic code and understand all the combinations of switches that exist.

An accurate chemical map of the human genome tells us surprisingly little about how it actually works. Transcribing¹³ the code of the genes, the Genome Project is not an end, but simply a beginning.


words to memorize

1. genomic imprinting:基因记忆
genomic correlation¹⁴ 基因相关
genomic exclusion¹⁵ 基因排斥

2.in a nutshell:简单说来

3.epigenetics:实验胚胎学

epigenetic:后天生成的，外遗传的

1 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

2 dealing   

n.经商方法，待人态度

参考例句：

• This store has an excellent reputation for fair dealing.该商店因买卖公道而享有极高的声誉。
• His fair dealing earned our confidence.他的诚实的行为获得我们的信任。

3 imprinting   

n.胚教，铭记（动物生命早期即起作用的一种学习机能）；印记

参考例句：

• He gathered her to himself, imprinting kisses upon her lips and cheeks. 他把她抱过来，吻着她的嘴唇和面颊。 来自辞典例句
• It'seems likely that imprinting is an extreme case of conditioning. 看来似乎铭记是适应的一种极端的情况。 来自辞典例句

4 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

5 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

6 tantalizing   

adj.逗人的；惹弄人的；撩人的；煽情的v.逗弄，引诱，折磨( tantalize的现在分词 )

参考例句：

• This was my first tantalizing glimpse of the islands. 这是我第一眼看见的这些岛屿的动人美景。 来自《简明英汉词典》
• We have only vague and tantalizing glimpses of his power. 我们只能隐隐约约地领略他的威力，的确有一种可望不可及的感觉。 来自英汉非文学 - 历史

7 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

8 attachment   

n.附属物，附件；依恋；依附

参考例句：

• She has a great attachment to her sister.她十分依恋她的姐姐。
• She's on attachment to the Ministry of Defense.她现在隶属于国防部。

9 dictated   

v.大声讲或读( dictate的过去式和过去分词 )；口授；支配；摆布

参考例句：

• He dictated a letter to his secretary. 他向秘书口授信稿。
• No person of a strong character likes to be dictated to. 没有一个个性强的人愿受人使唤。 来自《简明英汉词典》

10 activated   

adj. 激活的 动词activate的过去式和过去分词

参考例句：

• The canister is filled with activated charcoal.蒸气回收罐中充满了活性炭。

11 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。

12 complexity   

n.复杂(性)，复杂的事物

参考例句：

• Only now did he understand the full complexity of the problem.直到现在他才明白这一问题的全部复杂性。
• The complexity of the road map puzzled me.错综复杂的公路图把我搞糊涂了。

13 transcribing   

（用不同的录音手段）转录( transcribe的现在分词 )； 改编（乐曲）（以适应他种乐器或声部）； 抄写； 用音标标出（声音）

参考例句：

• They continue to remove molecules until the cell stops transcribing the gene. 他们继续除去分子，直到细胞不再转录基因为止。
• Q: Can I use Voice-to-Text software to help with the transcribing? 问：我能使用声音-到-本文的软件帮助转换吗？

14 correlation   

n.相互关系，相关，关连

参考例句：

• The second group of measurements had a high correlation with the first.第二组测量数据与第一组高度相关。
• A high correlation exists in America between education and economic position.教育和经济地位在美国有极密切的关系。

15 exclusion   

n.拒绝，排除，排斥，远足，远途旅行

参考例句：

• Don't revise a few topics to the exclusion of all others.不要修改少数论题以致排除所有其他的。
• He plays golf to the exclusion of all other sports.他专打高尔夫球，其他运动一概不参加。