大學(xué)生物專業(yè)英語(yǔ)lessonth-文庫(kù)吧
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【正文】 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 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) 。 Such cycling in effect makes singlecelled anisms immortal. 此循環(huán)可以有效的使得單細(xì)胞生物永生 。 College of Life Sciences Hubei Normal University 2022/2/10 15 Many cells in multicellular anisms, including animal muscle and nerve cells, either slow the cycle or break out of it altogether. 多細(xì)胞生物中的許多細(xì)胞 ， 包括動(dòng)物肌肉和神經(jīng)細(xì)胞 ，要么減慢周期速度 ， 要么一起脫離細(xì)胞周期 。 The normal cell cycle consists of four phases. 正常細(xì)胞周期由 4個(gè)時(shí)期組成 。 College of Life Sciences Hubei Normal University 2022/2/10 16 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. 前三個(gè)時(shí)期包括 G1,正常新陳代謝時(shí)期； S期 , 生物分子的合成繼續(xù) ， 同時(shí) ， DNA復(fù)制 ， 組蛋白合成； G2 期， 新陳代謝和進(jìn)一步生長(zhǎng)的短暫時(shí)期 。 Together the G1, S, and G2 phases are called interphase. G1, S, 和 G2一起稱為分裂間期 。 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。 College of Life Sciences Hubei Normal University 2022/2/10 18 It is believed that properties of the cell cytoplasm control the cell cycle, along with external stimulators and inhibitors such as chalones. 據(jù)稱是細(xì)胞質(zhì)中的物質(zhì)與外來(lái)的激活因子和抑制因子如抑素等一起控制了細(xì)胞周期。 College of Life Sciences Hubei Normal University 2022/2/10 19 3. Mitosis: partitioning the hereditary material 有絲分裂： 遺傳物質(zhì)的分離 College of Life Sciences Hubei Normal University 2022/2/10 20 Biologists divide the mitotic cycle into four phases. 生物學(xué)家將有絲分裂劃分為 4個(gè)階段 。 At the beginning of prophase the chromosomes each consist of two highly condensed chromatids attached to each other at a centromere. 分裂前期 ， 每個(gè)染色體是由高度濃縮的通過(guò)著絲粒連接在一起的兩個(gè)染色單體組成 。 (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 。 (在分裂前期后期和分裂中期前期 ， 濃縮的染色體與紡錘體相連 ) Eventually the chromosomes bee arranged in
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