大學(xué)生物專業(yè)英語(yǔ)lessonth-wenkub
2023-01-28 19:15:23 本頁(yè)面
【正文】 。 Together the G1, S, and G2 phases are called interphase. G1, S, 和 G2一起稱為分裂間期 。 The normal cell cycle consists of four phases. 正常細(xì)胞周期由 4個(gè)時(shí)期組成 。 those with cells containing a single set of parental chromosomes are called haploid. 細(xì)胞里含有兩套親本染色體的生物體稱二倍體；細(xì)胞里含有單套染色體的生物體稱單倍體 。 College of Life Sciences Hubei Normal University 2022/2/10 10 A pictorial display of an anism39。 Within the nucleus are the chromosomes—tightly coiled strands of DNA and clusters of associated proteins. 細(xì)胞核里的是染色體－－緊密盤(pán)繞成螺旋的 DNA鏈和相關(guān)的成簇蛋白質(zhì) 。 College of Life Sciences Hubei Normal University 2022/2/10 8 Long stretches of the continuous DNA molecule wind around these clusters of proteins, or histones, forming beadlike plexes known as nucleosomes. 長(zhǎng)鏈 DNA分子纏繞著成簇的蛋白質(zhì) ， 或組蛋白 ，形成珠鏈狀的核小體 。s chromosomes in the coiled, condensed state is known as a karyotype. 生物體中的致密的超螺旋狀態(tài)的染色體的表型稱為核型 Karyotype reveal that in most cells all but sex chromosomes are present as two copies, referred to as homologous pairs. 表型顯示：在大多數(shù)細(xì)胞里 ， 除了性染色體外 ， 其它的染色體都是成對(duì)出現(xiàn)的 ， 稱之為同源染色體對(duì) 。 College of Life Sciences Hubei Normal University 2022/2/10 12 College of Life Sciences Hubei Normal University 2022/2/10 13 2. The cell cycle 細(xì)胞周期 College of Life Sciences Hubei Normal University 2022/2/10 14 The 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. 細(xì)胞周期遵循特定的程序：細(xì)胞生長(zhǎng) ， 分裂準(zhǔn)備 ， 分裂成 2個(gè)子細(xì)胞 ， 每個(gè)子細(xì)胞再循環(huán) 。 College of Life Sciences Hubei Normal University 2022/2/10 16 The first three include G1, the period of normal metabolism。 College of Life Sciences Hubei Normal University 2022/2/10 17 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. 細(xì)胞周期的第四個(gè)時(shí)期是 M期，有絲分裂期，復(fù)制的染色體濃縮，移動(dòng)并細(xì)胞分裂。 (分裂前期 ， 高度濃縮的兩個(gè)染色單體通過(guò)著絲粒連接在一起形成染色體 ) College of Life Sciences Hubei Normal University 2022/2/10 21 As prophase ends and metaphase begins, the condensed chromosomes bee associated with the spindle. 分裂前期結(jié)束 ， 緊接著是分裂中期 ， 濃縮的染色體與紡錘體相連 。 College of Life Sciences Hubei Normal University 2022/2/10 23 As mitosis proceeds, the spindle microtubules play a crucial role in ensuring that both paired and separated chromatids move in the right directions at the proper times. 在有絲分裂過(guò)程中 ， 紡錘體微管在確保染色單體配對(duì)和在適當(dāng)時(shí)間以正確方向進(jìn)行分離中發(fā)揮了關(guān)鍵性的作用。 College of Life Sciences Hubei Normal University 2022/2/10 25 Mitosis: prophase metaphase anaphase telophase ?chromosome condensation ?mitotic spindle assembly ?nuclear envelope breakdown ?chromosomes align in the cen
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