英语听力：自然百科 人类血型的秘密

Kasey on Why Tell me Why. Someone asked why veins¹ are blue and blood is red. So that's part of this question: why do we have different blood types?

"Blood types are inherited, just like you inherit your eye color, or your hair texture², so you get a gene³ from each parent, and that determines what the child's blood type is gonna be."

There's sort for blood types?

"There is, there is A, type A, type B, type AB, and type O. The only difference is what sugar molecule⁴ is added to that point. So they are actually kind of generate from each other.

So for you to have O, both of your parents must be O. An O can contribute an O.

But, if, for example, your father was A and your mother was O, he could actually, one of his parents might have also been O, so he can contribute either an A gene or an O gene, that you could be O, cause you get an O from him and from your mother, while your sister might be an A.

There are some studies that show that the reason that A, B, O and AB have been distributed the way they were was because of forces that they think of primarily connected to the organism that causes malaria⁵. It turned out to be that people who had type O were actually able to survive an attack of malaria. It appeared that malaria organism was more readily able to attach to red cells that were type A or type B, and actually kill those patients before they have a chance to reproduce.

Those people who had type O actually would get sick, but wouldn't die, and had an opportunity to reproduce, and that's how the gene goes forward.

And then, if you look at a map of where malaria is now and where the different peoples are, you can see that the type O was followed, there is where there's malaria, A and B has gone to colder climates where malaria wasn't a problem, and then AB was just, you know, combination of the races."

1 veins   

n.纹理；矿脉( vein的名词复数 )；静脉；叶脉；纹理

参考例句：

• The blood flows from the capillaries back into the veins. 血从毛细血管流回静脉。 来自《简明英汉词典》
• I felt a pleasant glow in all my veins from the wine. 喝过酒后我浑身的血都热烘烘的，感到很舒服。 来自《简明英汉词典》

2 texture   

n.(织物)质地；(材料)构造；结构；肌理

参考例句：

• We could feel the smooth texture of silk.我们能感觉出丝绸的光滑质地。
• Her skin has a fine texture.她的皮肤细腻。

3 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。

4 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

5 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。