题干

来自约翰霍普金斯医学院,细胞动力学中心等处的研究人员利用一种新技术,观测到每一刻人类活细胞中一个分子的精确运动,从而帮助科学家们了解一个蛋白为什么和如何在一个位点是用于细胞分裂和生长,而在另外一个位点却是意味着细胞死亡。“一种特殊蛋白的激活位点,以及这种活性的长短能影响细胞对外界刺激作出的反应”,Takanari Inoue博士表示,“我们的目标就是通过这种新型技术,在细胞的各处快速操纵蛋白活性。下列关于蛋白质的叙述正确的是:     

A:所有的蛋白质都是由氨基酸构成的,所有的生物都有必需氨基酸和非必需氨基酸

B:所有的生物都有独立合成蛋白质的能力

C:蛋白质提前表达或过量表达可能导致生物性状发生改变

D:研究蛋白质的激活位点,只对治疗癌症有重要作用

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C

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   Height is just one of the thousands of features your genes decide. In fact, because you have two parents, your genes provide you a height that usually lands somewhere between the height of each parent. If both your parents are tall, then most probably you will be tall, too, but if you have questions about how tall you're going to be, ask your doctor if he or she can help you find it out.
    But genes don't decide everything. For example, eating an unhealthy diet can keep you from growing to your full potential(潜力). Getting plenty of sleep and enough exercise will help you grow to the expected height.
    No doubt you're wondering how fast you should grow. It depends. There's no perfect or right answer. Generally speaking, kids grow about 2 inches (6 centimeters) a year between age 3 and the time when they start puberty (when your body starts changing and becoming more grown up).
    Your doctor will know how your growth has been going over the years. Two centimeters here and 2 inches there are not nearly as important as the height you're at now, how you've been growing up to this point, and what other changes your body may be going through.
    Don't be scared if you seem to have grown a lot in a very short time. Everyone has a growth spurt(高峰)during puberty. The age for starting puberty is about 10 for girls and about 11 for boys. But it can be earlier or later ----between 7 and 13 for girls and 9 and 15 for boys.
    You'll usually begin to notice that you're growing faster about a year or so after your body starts to show the first changes of puberty.