【生物-选修3：现代生物科技专题】
在体内，人胰岛素基因表达可合成出一条称为前胰岛素原的肽链，此肽链在内质网中经酶甲切割掉氨基端一段短肽后称为胰岛素原，进入高尔基体的胰岛素原经酶乙切割去除中间片段C后，产生A、B两条肽链，再经酶丙作用生成由51个氨基酸残基组成的胰岛素。目前，利用基因工程技术可大量生产胰岛素。回答下列问题：
（1）人体内合成前胰岛素原的细胞是____________，合成胰高血糖素的细胞是______________。
（2）可根据胰岛素原的氨基酸序列，设计并合成编码胰岛素原的__________序列，用该序列与质粒表达载体构建胰岛素原基因重组表达载体。再经过细菌转化、筛选及鉴定，即可建立能稳定合成_____________的基因工程菌。
（3）用胰岛素原抗体检测该工程菌的培养物时，培养液无抗原抗体反应，菌体有抗原抗体反应，则用该工程菌进行工业发酵时，应从______________中分离、纯化胰岛素原。胰岛素原经酶处理便可转变为胰岛素。
As you are probably aware, the latest job markets news isn’t good: Unemployment is still more than 9 percent, and new job growth has fallen close to zero. That’s bad for the economy, of course. And it may be especially discouraging if you happen to be looking for a job or hoping to change careers right now. But it actually shouldn’t matter to you nearly as much as you think.
That’s because job growth numbers don’t matter to job hunters as much as job turnover (人员更替) data. After all, existing jobs open up every day due to promotions, resignations, terminations (解雇), and retirements. (Yes, people are retiring even in this economy.) In both good times and bad, turnover creates more openings than economic growth does. Even in June of 2007, when the economy was still moving ahead, job growth was only 132,000, while turnover was 4.7 million!
And as it turns out, even today — with job growth near zero — over 4 million job hunters are being hired every month.
I don’t mean to imply that overall job growth doesn’t have an impact on one’s ability to land a job. It’s true that if total employment were higher, it would mean more jobs for all of us to choose from (and compete for). And it’s true that there are currently more people applying for each available job opening, regardless of whether it’s a new one or not.
But what often distinguishes those who land jobs from those who don’t is their ability to stay motivated. They’re willing to do the hard work of identifying their valuable skills; be creative about where and how to look; learn how to present themselves to potential employers; and keep going, even after repeated rejections. The Bureau of Labor Statistics data shows that 2.7 million people who wanted and were available for work hadn’t looked within the last four weeks and were no longer even classified as unemployed.
So don’t let the headlines fool you into giving up. Four million people get hired every month in the U.S. You can be one of them.
如图所示，一个质量为的物体与绕在定滑轮上的绳子相连，绳子的质量可以忽略，它与定滑轮之间无滑动。假设定滑轮质量为，半径为，其转动惯量为，滑轮轴光滑。试求该物体由静止开始下落的过程中，下落速度与时间的关系。
如图所示，质量为，长为直杆，可绕水平轴无摩擦地转动。设一质量为的子弹沿水平方向飞来，恰好射入杆的下端，若直杆（连同射入的子弹）的最大摆角为，则子弹的速度为（ ）
如图所示，一质量为的均匀细直杆，端靠在光滑的竖直墙壁上，端置于水平地面上，杆身与竖直方向角，端对壁的压力大小为（ ）
一个质量为、半径为并以角速度旋转的均质飞轮的边缘飞出，且速度方向正好竖直向上，如图所示。余下部分的转动动能为（ ）（可忽略重力距的影响）