首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
In 1999 when MiShel and Carl Meissner decided to have children, they tackled the next big issue: Should they try to have a girl?
In 1999 when MiShel and Carl Meissner decided to have children, they tackled the next big issue: Should they try to have a girl?
admin
2012-02-27
36
问题
In 1999 when MiShel and Carl Meissner decided to have children, they tackled the next big issue: Should they try to have a girl? It was no small matter. MiShel’s brother had become blind from a hereditary condition in his early 20s, and the Meissners had learned that the condition is a disorder passed from mothers to sons. If they had a boy, he would have a 50 per cent chance of having the condition. A girl would be unaffected. The British couple’s inquiries about sex selection led them to Virginia, US, where a new sperm-separation technique, called MicroSort, was experimental at the time. When MiShel became pregnant she gave birth to a daughter. Now they will try to have a second daughter using the same technique.
The technique separates sperm into two groups—those that carry the X-chromosome (染色体) producing a female baby and those that carry the Y-chromosome producing a male baby.
The technology was developed in 1990s, but the opening of a laboratory in January 2003 in California marked the company’s first expansion. "We believe the number of people who want this technology is greater than those who have access to it," said Keith L. Blauer, the company’s clinical director.
This is not only a seemingly effective way to select a child’s gender. It also brings a host of ethical (伦理的) and practical considerations—especially for the majority of families who use the technique for nonmedical reasons.
The clinic offers sex selection for two purposes: to help couples avoid passing on a sex-linked genetic disease and to allow those who already have a child to "balance" their family by having a baby of the opposite sex.
Blauer said the company has had an impressive success rate: 91 per cent of the women who become pregnant after sorting for a girl are successful, while 76 per cent who sort for a boy and get pregnant are successful.
The technique separates sperm based on the fact that the X chromosome is larger than the Y chromosome. A machine is used to distinguish the size differences and sort the sperm accordingly.
The sperm-separation technique is based on the fact that the chromosomes responsible for babies’ sex ______.
选项
A、are of different shapes
B、are of different sizes
C、can be identified
D、can be reproduced
答案
B
解析
文章最后一段作者说:分离精子的技术是基于X染色体比Y染色体大。科学家用一种机器把大小不同的染色体分开。
转载请注明原文地址:https://kaotiyun.com/show/Nshi777K
0
在职申硕(同等学力)英语
相关试题推荐
女性,70岁,右下唇皮肤肿物不断增大半年,直径约1.5cm大小,近半个月来破溃出血。病理检查肿瘤细胞异型性明显,角化珠形成,已浸润至肌肉组织。符合该患者诊断的是
TodayblackchildreninsouthAfricaarestillreluctanttostudysubjectsfromwhichtheywereeffectivelybarredforsolong.
Shouldeitherofthesesituationsoccur,wrongcontrolactionsmightbetakenandapotentialaccidentsequenceinitiated.
Americanculturehasnotbeenimmunetoculturalinfluencesfromoutside.TheideaofdemocracycamefromtheancientGreeks:th
TheVikingshaveleftmanytracesoftheirsettlementwhicharestillvisibletoday.Archaeologyprovidesphysicalevidenceoft
Directions:Inthispartyouaretowriteacompositionofnolessthan150wordsabout"WomeninModernTimes".Youshouldwrit
Manystudentsfindtheexperienceofattendinguniversitylecturestobeaconfusingandfrustratingexperience.Thelecturersp
MoreAmericanmothersthaneverareworking,andmoreworkersaremothers.Yettheirmarchintotheworldofpaidworkcontinues
AfascinatingnewstudyrevealsthatAmericansaremorelikelytocalltheirchildren"intelligent,"whileEuropeanparentsfocu
Ifyoustarteachdaydesperatelywishingforanextrahourinbed,thefollowingislikelytoleaveyoufeelingevenmorebad-t
随机试题
现场钻取路面结构的代表性试样时,芯样的直径不宜小于集料最大粒径的()倍。
国际物流信息系统的主要特征包括()
Allovertheworld,forestsaresafeguardingthehealthoftheplanetitself.Theydothis【C1】______protectingthesoil,providi
术后半卧位的目的不包括()。
影响药物稳定性的外界因素不包括()。
背景资料:某堤防工程项目业主与承包商签订了工程施工承包合同。合同中估算工程量为5300m3,单价为180元/m3。合同工期为6个月。有关付款条款如下:(1)开工前业主应向承包商支付估算合同总价20%的工程预付款;(2)业主自第
可转换公司债券的利率由发行公司与主承销商确定,但必须符合国家的有关规定。()
下列关于贷款档案管理期限的说法中,不正确的是()
企业按照销售百分率法预测出来的资金需要量,是企业在未来一定时期资金需要量的增量。()
徐徐:缓缓
最新回复
(
0
)