Some are exchanged via small loops of DNA called plasmids.

一些基因会通过被称为质的DNA小环交换。

Additionally to the genetic material contained within the nucleoid, many bacteria contain extra chromosomal DNA molecules called plasmids.

除了包在拟核中的遗传物质外，许多细菌有额外的DNA分子，称为质。

However, plasmids often contain genes that confer a selective advantage to the bacterium such as resistance to antibiotics.

不过质通常包赋予细菌选择性优势的基因，例如抗生素耐药性。

Then they dropped the plasmid into a living bacterium, or yeast.

然后他们将质放入活细菌或酵母中。

Plasmids have relatively few genes and their genetic information is not essential to the bacterium and cells that lack them usually function normally.

质所的基因相对较少，并且它们的基因对细菌说并不是必须的，缺少质的细胞往往也常生长。

The plasmid enters and multiplies itself within a cell and can then be transferred to others.

质进入细胞并在细胞内繁殖， 然后转移到其他细胞中。

So essentially, these plasmids are the vehicles that transfer genes for antibiotic resistance between different bacterial species.

因此，从本质上讲，这些质是在不同细菌物种之间转移抗生素抗性基因的载体。

This plasmid mutation has been seen in other places before; in China, in animals and some human patients.

这种质突变前在其他地方也见过；在中国，在动物和一些人类患者中。

Purification of the desired target fragment.

5。将片段与新的质载体连接组建一个新的重组分子。

Initially, production in bacteria was the only route available and cDNA clones were used as they contained no introns.

cDNA需要与原核生物的转录和翻译信号相连，并且需要插入多拷贝的质。

But this is the first time the plasmid has been found in the United States, and it could get passed around quickly.

但这是第一次在美国发现这种质，它能会很快传播开。

Phage h can be used to clone fragments larger than plasmid vectors, and phage M13 allows cloned DNA to be isolated in single-stranded form.

更多载体被改造能同时拥有质和噬菌体的一些特性，像被称为粘的质-噬菌体λ杂交体。

More specialized vectors have been engineered to use aspects of plasmids and bacteriophages, such as the plasmid-bacteriophage h hybrids known as cosmids

质和噬菌体已经在很多种类的细菌中被使用表达基因，并且一些噬菌体也许已经被用将DNA整合到宿主基因组上。

Or, in plain english, plasmids are part of the reason that, one day, antibiotics may not be able to help your strep throat anymore.

或者，用简单的英语说，质是有一天抗生素能无法再帮助您治疗链球菌性咽喉炎的部分原因。

I did all these experiments actually, with my own hands, I was 58 years old, I was still culturing plasmids and feeding cells, so it is very unlikely.

实际上，所有这些实验都是我亲手做的，当时我 58 岁，我还在培养质和喂养细胞，所这是非常不能的。

The cytoplasm contains ribosomes which are the site of protein synthesis, the nucleoid which contains the genetic material, and plasmids which contain genes that confer a selective advantage to the bacterium.

细胞质中有核糖体，它们是蛋白质合成的部位；拟核有遗传物质及质；质有赋予细菌选择性优势的基因。

This might be used to investigate a short region of a large cloned fragment in more detail, or to transfer a gene to a vector designed to express it in a particular species, for example.

大肠杆菌中的质载体为例（最常见），这个过程分为下步骤。

And the thing that makes this mutation especially troubling is that it was found on a plasmid -- a little piece of DNA that can be easily shared between neighboring bacteria, meaning it can spread more easily.

让这种突变特别麻烦的是它是在质上发现的——一小段 DNA 很容易地在相邻细菌之间共享，这意味着它更容易地传播。

Vectors also incorporate a selectable marker, a gene which allows host cells containing the vector to be selected from amongst those which do not, usually by conferring resistance to a toxin, or enabling their survival under certain growth conditions.

最初的大肠杆菌载体是染色体外的环形质，并且相当数量的噬菌体（感染细菌的病毒）也被用在大肠杆菌中。