英语翻译In fact,the specific biological mechanisms that allow parents to transmit their features to their offspring were an enormous mystery until about 140 years ago.Scientists back then knew that parents somehow made a tiny copy of themselves i

英语翻译In fact,the specific biological mechanisms that allow parents to transmit their features to their offspring were an enormous mystery until about 140 years ago.Scientists back then knew that parents somehow made a tiny copy of themselves i
英语翻译
In fact,the specific biological mechanisms that allow parents to transmit their features to their offspring were an enormous mystery until about 140 years ago.Scientists back then knew that parents somehow made a tiny copy of themselves inside an egg or a sperm,but they had no idea what these copies were or how they worked.
Then,in the 1860s,an Austrian monk named Gregor Mendel started breeding peas in his garden.Where others saw only plants,Mendel looked deeper and found the basic units of heredity we now call genes.If you remember from the last chapter,genes are the parts of a chromosome that are transcribed to mRNA and are ultimately translated to the proteins essential to cellular processes.Mendel had no knowledge of protein synthesis and had never seen a chromosome,but his simple experiments with peas and the laws he developed to describe the behavior of hereditary—now termed classical genetics—have provided the foundation for the modern field of molecular genetics,the study of heredity on the molecular level.
For the SAT II Biology,you need a solid understanding of the basic laws and patterns of both classical genetics and molecular genetics.Questions on genetics can make up anywhere from 14 to 20 percent of the core of the SAT II Biology.In addition,the “M” section of the Biology E/M test focuses on evolution in terms of molecular biology,including genetics.
Basis of Inheritance:Meiosis
Mitosis takes a diploid cell and creates a nearly exact copy.Mitosis has two main functions:(1) it leads to the creation of all of the somatic (body) cells in humans and other living organisms; (2) in organisms that undergo asexual reproduction,diploid parent cells undergo mitosis to create identical daughter copies of themselves.Mitosis creates a daughter cell with chromosomes that are identical to the chromosomes in its parent cell.
But humans and most other complex plants and animals each have a unique set of chromosomes.This diversity of chromosomes is the result of sexual reproduction,which involves the contribution of the genetic material from not one,but two parents.During sexual reproduction the father’s haploid sperm cell and the mother’s haploid ovum (egg) cell fuse to form a single-celled diploid zygote that then divides billions of times to form a whole individual.
In order for sexual reproduction to take place,however,the parents first need to have haploid sperm or ova,also called sex cells,germ cells,or gametes.Meiosis is the name for the special type of cell division that produces gametes.

英语翻译In fact,the specific biological mechanisms that allow parents to transmit their features to their offspring were an enormous mystery until about 140 years ago.Scientists back then knew that parents somehow made a tiny copy of themselves i
In fact,the specific biological mechanisms that allow parents to transmit their features to their offspring were an enormous mystery until about 140
years ago.Scientists back then knew that parents somehow made a tiny copy of themselves inside an egg or a sperm,but they had no idea what these
copies were or how they worked.
实际上,生物从上一代遗传到下一代的秘密直到140年才被揭开.那时候的科学家已经觉察到父母貌似是在精子和卵子里面有一份微
小的复制,但是他们不清楚这些复制是什么以及怎么起作用的.
If you remember from the last chapter,genes are the parts of a chromosome that are transcribed to mRNA and are ultimately translated to the
proteins essential to cellular processes.Mendel had no knowledge of protein synthesis and had never seen a chromosome,but his simple
experiments with peas and the laws he developed to describe the behavior of hereditary—now termed classical genetics—have provided the
foundation for the modern field of molecular genetics,the study of heredity on the molecular level.
接着,1860年,一个叫孟德尔的奥地利和尚开始在他的花园里面种豌豆.在常人眼里的植物,孟德尔却在细心研究之后发现了我们
现在称之为基因的遗传基本物质.如果你还记得上一章的内容,基因就是染色体的一部分,他们转录成信使RNA,然后转译成对细胞
活动很重要的蛋白质.孟德尔没有蛋白质合成的知识,也从来没见过染色体,但是他的简单的豌豆实验和他发明的遗传理论解释了
遗传的行为--现在我们称为经典基因学---给现代分子基础上的遗传学,也就是分子基因学,奠定了基础
For the SAT II Biology,you need a solid understanding of the basic laws and patterns of both classical genetics and molecular genetics.Questions on
genetics can make up anywhere from 14 to 20 percent of the core of the SAT II Biology.In addition,the “M” section of the Biology E/M test focuses on
evolution in terms of molecular biology,including genetics.
SAT二级的生物,你需要对经典基因学和分子基因学的基本理论有清楚的认识.基因学的题占了SAT二级的生物学的14-20%.另外,生
物学E/M测试的的M部分主要在进化论上面,包括分子生物学的基因学.
Basis of Inheritance:Meiosis
Mitosis takes a diploid cell and creates a nearly exact copy.Mitosis has two main functions:(1) it leads to the creation of all of the somatic (body) cells
in humans and other living organisms; (2) in organisms that undergo asexual reproduction,diploid parent cells undergo mitosis to create identical
daughter copies of themselves.Mitosis creates a daughter cell with chromosomes that are identical to the chromosomes in its parent cell.
But humans and most other complex plants and animals each have a unique set of chromosomes.This diversity of chromosomes is the result of
sexual reproduction,which involves the contribution of the genetic material from not one,but two parents.During sexual reproduction the father’s
haploid sperm cell and the mother’s haploid ovum (egg) cell fuse to form a single-celled diploid zygote that then divides billions of times to form a
whole individual.
In order for sexual reproduction to take place,however,the parents first need to have haploid sperm or ova,also called sex cells,germ cells,or
gametes.Meiosis is the name for the special type of cell division that produces gametes.
遗传的基础：减数分裂
有丝分裂让一个二倍体生成一个同样的复制.有丝分裂有两个重要的功能：1.它构建了人和其它生物的所有体细胞2.在单性生殖的生
物体里面,上一代生物体通过有丝分裂生成同样的新个体.新个体里面的染色体和母体完全相同.但是包括人在内的其它复杂动植
物都有一组独特的染色体.这些多样性的染色体从不是一个而是两个父母通过有性生殖的结果.在有性生殖的过程里,来自父本的
单倍体精子和母本的单倍体卵细胞合成一个二倍体受精卵细胞,这个细胞接下来复制上亿次成为新的个体
有性生殖要发生,需要父母的单倍体,也被称为性细胞/配偶子的精细胞和卵细胞.减数分裂就是细胞生成这样的配偶子的特殊分裂方式

事实上,父母能把他们的特征传给他们的后代的这个生物机制直到140年前还仍然是一个巨大的谜团。科学家们后来得知父母以某种方式在一个卵子或一个精子里制造出一个他们自身的微小的拷贝，但是对于这些拷贝究竟是些什么，以及他们起着怎样的作用却一无所知。
后来,十九世纪六十年代，奥地利修士格雷戈.孟德尔开始在他的菜园里种豌豆。在他人眼里看来不过是些植物，而孟德尔却看到了更深层的东西，并发现了遗传的基本单...

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事实上,父母能把他们的特征传给他们的后代的这个生物机制直到140年前还仍然是一个巨大的谜团。科学家们后来得知父母以某种方式在一个卵子或一个精子里制造出一个他们自身的微小的拷贝，但是对于这些拷贝究竟是些什么，以及他们起着怎样的作用却一无所知。
后来,十九世纪六十年代，奥地利修士格雷戈.孟德尔开始在他的菜园里种豌豆。在他人眼里看来不过是些植物，而孟德尔却看到了更深层的东西，并发现了遗传的基本单位，也就是我们现在所说的基因。如果你回顾上一章,基因是染色体的一部分，被转录成信使RNA，最终转化成蛋白质，这是必不可少的的细胞代谢过程。孟德尔没有蛋白质合成的相关知识也从未见过染色体,但是他简单的豌豆实验和他发展并描述的遗传行为——现在被称为古典遗传学——为现代的分子遗传学和在分子水平上遗传研究奠定了基础。
关于SAT‖生物学，你需要对古典遗传学和分子遗传学的基本法则和模式有一个深刻的了解。遗传学问题占SAT‖生物学核心内容的14～20%。此外,生物学E/M的M部分就分子生物学来说测试进化部分,包括遗传学。
遗传的分子基础:减数分裂
有丝分裂取一个二倍体细胞和创造一个几乎位几乎一模一样的拷贝。有丝分裂有两个主要功能:一它导致人类和其它生物体的体细胞的创造；二对有机体来说是经历了无性生殖,二倍体母细胞经历有丝分裂以创造恒等的子细胞。有丝分裂创造出与母细胞染色体相同的子细胞。
但是人类和大多数复杂的植物和动物都各自有一套独特的染色体。染色体的多样性是有性生殖产生的结果,其原因包括遗传物质不是由单个个体而是由父母双方提供的。在有性生殖过程中，来自父方的单倍体的精细胞和来自母方的单倍体的卵细胞融合并形成了一个单一的双倍体的合子，然后经过亿万次的分裂形成一个完整的个体。
为了进行有性生殖,不管怎样,父母必须产生一个单倍体的精子或者卵子,也叫性细胞、生殖细胞或者配子。减数分裂是一特殊类型的细胞分裂的名称，这种细胞分裂可以产生配子。

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