原核生物是缺乏细胞核和细胞器的简单细胞。他们的DNA由一个或两个圆形染色体组成。相比之下,真核生物是具有细胞核,细胞器和多个线性染色体的复杂细胞。在两种类型的细胞中,DNA被复制并分离以有组织的方式形成新细胞。在两种类型的细胞中,细胞质通过胞质分裂过程分裂成子细胞。在这两个过程中,如果一切按计划进行,则子细胞包含父细胞DNA的精确拷贝。在细菌细胞中,该过程更简单,使裂变比有丝分裂更快。因为细菌细胞是完整的生物体,裂变是一种繁殖形式。虽然有一些单细胞真核生物,但有丝分裂最常用于生长和修复而不是繁殖。虽然裂变中复制的错误是在原核生物中引入遗传多样性的一种方式,但有丝分裂中的错误可能在真核生物中引起严重问题(例如,癌症)。有丝分裂包括一个检查点,以确保两个DNA拷贝是相同的。真核生物利用减数分裂和有性繁殖来确保遗传多样性。

美国普林斯顿大学Essay代写:二元裂变与有丝分裂

Prokaryotes are simple cells that lack a nucleus and organelles. Their DNA consists of one or two circular chromosomes. Eukaryotes, in contrast, are complex cells that have a nucleus, organelles, and multiple linear chromosomes. In both types of cells, DNA is copied and separated to form new cells in an organized manner. In both types of cells, cytoplasm is divided to form daughter cells via the process of cytokinesis. In both processes, if everything goes as planned, the daughter cells contain an exact copy of the parent cell’s DNA. In bacterial cells, the process is simpler, making fission faster than mitosis. Because a bacterial cell is a complete organism, fission is a form of reproduction. While there are some single-celled eukaryotic organisms, mitosis is most often used for growth and repair rather than reproduction. While errors in replication in fission are a way to introduce genetic diversity in prokaryotes, errors in mitosis can cause serious problems in eukaryotes (e.g., cancer). Mitosis includes a check point to make certain both copies of DNA are identical. Eukaryotes use meiosis and sexual reproduction to ensure genetic diversity.

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