联合晚报生物专业英语(蒋悟生 第二版)课文翻译lesson three

2021年1月20日发(作者：匾)
Lesson Three
（
2
学时）

Cellular Reproduction:

Mitosis and Meiosis
教学目 的：使学生掌握
细胞的有丝分裂和
无丝分裂
的作用机理，
有丝分裂和
无丝分裂
之间的区别和相同点。
相关英
语词汇以及主要用法。
教学重点：有丝分裂和
无丝分裂
中相关的概念和功能，
及相关英语词
汇的掌握教学难 点：
专业英语词汇的记忆讲授方法：
以学生翻译为主，
老师讲解相关专业知
识 辅助学生理解授课时间：
4
月
12
日教学内容：


The Nucleus and ChromosomesThe cell nucleus is the main repository of genetic information.

Within the nucleus are the chromosomes tightly coiled strands of DNA and clusters of associated
proteins.

Long stretches of the continuous DNA molecule wind around these clusters of proteins,
or histones, forming beadlike complexes known as nucleosomes. More coiling and supercoiling
produces
a
dense
chromosome
structure.
Each
long
strand
of DNA
combines
with histones
and
nonhistone proteins to make up the substance chromatin.
细胞核是贮藏
遗传信息
的 主要场所。
DNA
盘绕成螺旋线以及相关的成簇蛋白质。
DNA
螺旋线缠绕成 簇的
组蛋白
形成珠链状的核
小体。这些螺旋和超螺旋形成致密的染色体组结构。每个长 链
DNA
与
组蛋白
和非
组蛋白
一
起构成
染 色质
物质。

A
pictorial
display
of
an
organism's
chromosomes
in
the
coiled,
condensed
state
is
known
as
a
karyotype.

Karyotype
reveal
that
in
most
cells
all
but
sex
chromosomes
are
present
as
two
copies,
referred
to
as
homologous
pairs.

Non-sex
chromosomes
are
called
autosomes.

Organisms whose cells contain two sets of parental chromosomes are called diploid; those with
cells containing a single set of parental chromosomes are called haploid.

染色体致密的超螺旋
状态我们称染色体组。
除了性染色体外，
大多数细胞的染色体组成对出现，
称 同源染色体对。
非性染色体称常染色体。
生物细胞含有两套父母本染色体的称
二倍体< br>；
含有单套染色体的称
单倍体。

The Cell CycleThe cell cycle is a regular sequence in which the cell grows, prepares for division,
and divides to form two daughter cells, each of which then repeats the cycle.

Such cycling in
effect makes single-celled organisms immortal.

Many cells in multicellular organisms, including
animal muscle and nerve cells, either slow the cycle or break out of it altogethe r.
在细胞生长过程
中，细胞循环遵循特定程序，分裂准备，分裂成
2
个子细 胞，子细胞再循环。此循环使得单
细胞永生。
多细胞生物中的许多细胞，包括动物肌肉和神经细 胞，
要么降低循环速度，
要么
同时分裂。

The normal cell cycle consists of four phases.

The first three include G1, the period of normal
metabolism; S phase, during which normal synthesis of biological molecules continues, DNA is
replicated,
and
histones
are
synthesized;
and
G2,
a
brief
period
of
metabolism
and
additional
growth.

Together the G1, S, and G2 phases are called interphase.

The fourth phase of the cell
cycle is M phase, the period of mitosis, during which the replicated chromosomes condense and
move
and
the
cell
divides.

It
is
believed
that
properties
of
the
cell
cytoplasm
control
the
cell
cycle, along with external stimulators and inhibitors such as chalones.
正 常细胞循环由
4
个时期组成。
头三期包括
G1,
正常新陈代谢；S
期
,
正常新陈代谢同时，
DNA
复制
，组蛋白合成；

G2
期，短期的新陈代谢和少许生长。
G1, S,
和
G2
称分裂间期。最后
是
M
期，有丝分裂期，复制的染色体组浓缩，移动并 细胞分裂。据称是
染色质
控制了细胞
循环，伴随外部激活因子和抑制因子如抑素。




Mitosis: Partitioning the Hereditary MaterialBiologists divide the mitotic cycle into four phases.

At the beginning of prophase the chromosomes each consist of two highly condensed chromatids
attached to each other at a centromere.

As prophase ends and metaphase begins, the condensed
chromosomes
become
associated
with
the
spindle.

Eventually
the
chromosomes
become