【英语时差8,16】动物界的染色体有何不同？（上）

In mammals, the sex of a baby is determined¹ by the combination of chromosomes³ it inherits from its parents. Nearly every cell in a male body has two different sex chromosomes–one is shaped like an X and one is shaped like a Y. Females also have two sex chromosomes in each cell but they are both X-shaped. When the male sperm⁴ and the female egg come together, each one contributes one sex chromosome². The female always contributes an X chromosome while the male can provide either an X or a Y. If the male provides an X then the embryo⁵ has two X chromosomes and becomes a female. If the male provides a Y then the embryo has one of each and grows into a male.

1 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

2 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

3 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

4 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

5 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。