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  • 性生殖 -- -- 高级

    Mating in common frogs

    Sexual vs. asexual: what's the main difference?
    ::性对性:主要区别是什么?

    Truly, it's just that sexual reproduction is the combining of sex from two parents, each providing half the amount of genetic material .
    ::确实,性生殖是双亲的性结合, 每一人提供一半的遗传物质。

    Sexual Reproduction
    ::性生殖

    Why do you look similar to your parents, but not identical? First, it is because you have two parents. Second, it is because of sexual reproduction. Whereas produces genetically identical clones, sexual reproduction produces genetically diverse individuals. Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. As both parents contribute half of the new organism’s genetic material, the offspring will have traits of both parents, but will not be exactly like either parent.
    ::为什么你看起来和父母相似,但并不完全相同?第一,是因为你有双亲。第二,这是因为性生殖。在生产基因相同的克隆时,性生殖会产生基因多样化的个人。性生殖是通过结合两种生物的遗传材料来创造新生物体。 由于父母双方贡献了新生物体的遗传材料的一半,因此后代将具有父母双方的特征,但不会完全像父母双方一样。

    Organisms that reproduce sexually by joining gametes , a process known as , must have a mechanism to produce haploid gametes. This mechanism is , a type of that halves the number of . Meiosis occurs only in gamete producing cells within the gonads . During meiosis the pairs of chromosomes separate and segregate randomly to produce gametes with one chromosome from each pair. Meiosis involves two nuclear and cell divisions without an interphase in between, starting with one diploid cell and generating four haploid cells ( Figure  ). Each division, named meiosis I and meiosis II, has four stages: prophase , metaphase , anaphase , and telophase . These stages are similar to those of , but there are distinct and important differences.
    ::性繁殖的有机体通过连成调子(一个称为调子的过程)必须有一个生成杂交调子的机制。 这个机制是, 一种机制, 一种机制, 使调子数量减半。 美化只在果子中的调子产细胞中发生。 在梅思滋期间, 染色体的对子分离并随机分离, 产生配有每对一种染色体的调子。 美思涉及两个核和细胞分裂, 两者之间没有相互交错, 从一个浸泡细胞开始, 产生四个杂交细胞( Figure ) 。 每个分区, 叫做 meiosis I 和 meiosis II , 都有四个阶段: 前期、 元阶段、 阶段和 调子阶段。 这些阶段与 相似, 但有不同且重要的差异 。

    Prior to meiosis, the cell’s is replicated, generating chromosomes with two sister chromatids. A human cell prior to meiosis will have 46 chromosomes, 22 pairs of homologous autosomes , and 1 pair of sex chromosomes . Homologous chromosomes , or homologues, are similar in size, shape, and genetic content; they contain the same genes , though they may have different of those genes. The genes/alleles are at the same loci on homologous chromosomes. You inherit one chromosome of each pair of homologues from your mother and the other one from your father. Sexual reproduction is the primary method of for the vast majority of , including almost all and plants. Fertilization joins two haploid gametes into a diploid zygote , the of a new organism. The zygote enters G 1 of the first , and the organism begins to grow and develop through mitosis and cell division.
    ::在美化之前,细胞被复制,用两个姐妹染色体生成染色体。在美化之前,人类细胞将拥有46种染色体、22对同质异体和1对性染色体。同族染色体或同族体在大小、形状和遗传内容上都相似;它们含有相同的基因,尽管它们可能与这些基因不同。基因/异性在同族染色体上处于同一个地方。你继承了你妈妈和父亲的每对同族体的染色体。性生殖是绝大多数人,包括几乎所有人和植物的主要方法。肥料化将两种手动的游戏结合到一种新生物的乳汁果中。zygote进入第一种染色体的G1,而生物则开始通过消化和细胞分裂来生长和发展。

    lesson content
    During meiosis the number of chromosomes is reduced from a diploid number (2n) to a haploid number No. During fertilization, haploid gametes come together to form a diploid zygote and the original number of chromosomes (2n) is restored.

    Summary
    ::摘要

    • Sexual reproduction involves haploid gametes and produces a diploid zygote through fertilization.
      ::性生殖涉及手淫的调子,通过施肥产生低脂的zygote。
    • Fertilization joins two haploid gametes into a diploid zygote.
      ::肥化把两个杂乱无章的游戏 结合成一个低潮的zygote。

    Review
    ::回顾

    1. Define sexual reproduction.
      ::定义性生殖。
    2. List the main differences between asexual and sexual reproduction.
      ::列出性生殖与性生殖的主要区别。
    3. Define meiosis.
      ::确定线性硬化症的定义。
    4. How many chromosomes does a diploid human cell have? How many chromosomes does a haploid human cell have?
      ::阴极人类细胞有多少染色体?