微生物介绍500字作文【一】
Dear Sir or Madam:
In my capacity as the chairman of Biochemistry and Molecular Biology Department, the School of Life Science, Nankai University, I deem it a pleasure to recommend Mr. Bruce Liu as a worthy candidate for graduate studies at the Department of Cell and Molecular Biology of your esteemed university.
Over the past four years, I delivered two important courses Genetics and Cell Engineering to the Mr. Liu‘s class and his performance was impressive. He is endowed with a strong curiosity in the quest for new knowledge. Before attending each class, he would make full preparations so that he could quickly assimilate what was being taught. Sometimes he could come up with some surprisingly thought-provocative questions and he had a habit of discussing important problems with me in great detail. During those discussions, he often brought with him valuable materials that he obtained from a large quantity of technical literature. Such an initiative enabled him to broaden his ken of knowledge extensively and to cultivate and significantly improve his ability in reading technical literature in English and to follow the latest scientific and technological development in the world. Therefore, even before he graduated, he had already distinguished himself from the rest of his classmates in his English proficiency. Furthermore, his indefatigable spirit of reading large amount of technical materials was not simply intended to secure high scores in his coursework, but more importantly, to satisfy his almost insatiable interest in biology.
Apart from this, I was also very impressed by Mr. Liu‘s hands-on ability in conducting experiments. For many complicated experiments, he undertook them with a rigorous and conscientious attitude and would always complete them satisfactorily. In dealing with crucial steps involved in the experiments, he tended to make bold hypotheses and conduct substantial observations, ultimately achieving remarkable results. All those testify to Mr. Liu‘s tremendous potential in academic research, especially in his analytical skills and in the execution of experimental procedures.
In addition to his scholastic aptitudes, Mr. Liu can be described as trustworthy in personality. His kind-hearted nature and his integrity have created many friends for him. By no means a bookworm, Mr. Liu took an active part in extracurricular activities in which he enhanced his group spirit and the sense of collectivism. His willingness to assist his classmates has brought him a very high reputation.
To summarize, Mr. Liu has been an outstanding student in our department and he is fully qualified to undertake high-level studies in a more challenging environment. His excellent qualities will undoubtedly facilitate him in achieving satisfactory results in his future academic pursuit and in his career.
Yours Sincerely
Professor and Chairman of Biochemistry and Molecular Biology Department
Nankai University
微生物介绍500字作文【二】
形成：细胞停止伸长生长以后时产生。分内层、中层和外层。
特点：由纤维素和其他非半纤维素物质如木质组成。
功能：机械支持。
微生物介绍500字作文【三】
核 膜：为双层结构，包含外膜和内膜。
核纤层：核内膜内侧一层蛋白质网络结构。
核 仁：是rRNA合成加工和装配核糖体亚单位的重要场所。
染色质：是间期细胞核遗传物质的存在形式。染色体是细胞有丝分裂时遗传物质的特定形式。
微生物介绍500字作文【四】
1、分生组织的概念：指植物体内保留的具有持久分裂能力的组织。
2、分生组织组成细胞的特点：细胞壁薄、体积小、原生质浓厚、细胞核大、液泡不明显。
3、分生组织的类型：
按位置分：
1）顶端分生组织分布于根、茎顶端形成初生植物体。
2）侧生分生组织分布于双子叶植物和裸子植物根、茎侧面形成植物体的次生结构。
3）居间分生组织位于植物顶端分生组织被成熟组织隔离而保留下来的部分。
按来源和性质分：
1）原生分生组织直接由植物胚胎里的细胞分裂保留下来的组织。
2）初生分生组织由原分生组织衍生细胞组成，已出现了分化，仍具有分裂能力。
3）次生分生组织由成熟组织经反分化成为具分裂能力的细胞。分为：维管形成层和木栓形成层。
4、组织的形成：成熟组织和非分生组织分生组织衍生的大部分细胞，逐渐丧失分裂能力，进一步生长和分化，形成的其它各种组织。
微生物介绍500字作文【五】
在短短的几个月高中学习生活中，教生物的张敏老师给我留下了深刻的印象。
生物老师很漂亮，乌黑的直发温柔地披在双肩，美丽的大眼睛在眼镜的衬托下显得格外有神，白晳的脸上始终挂着微笑，显得非常平易近人。
生物老师让我触动很深还得从那堂晚自习说起。
那节晚自习，是生物老师的辅导课。上课铃响过，生物老师轻手轻脚地走进教室，唯恐惊扰了正在看书的我们。教室里很安静，能听得到笔尖在纸上摩擦的声音，我趴在桌子上写作业，一道数学证明题已困扰我多时了，我在草稿纸上画了很长时间，也未能算出正确答案，心中不免有些烦躁，索性趴在桌子上看着那道题发呆。
我隐隐约约听见身后有一阵细微的脚步声，我知道一定是生物老师。便抓起笔，在草稿纸上重新演算起那道题目。脚步声在我身边停止。
生物老师轻轻地弯下腰，把我的作业本摆正，柔声说道：“写字姿势要端正，看你本子歪的，离书又这么近，会近视的。”在她低头的一瞬间，我闻到了她的发香，很淡很淡，却令人神清气爽。生物老师朝我微微一笑，走了。
心里突然间像被什么细细小小的东西迅速占据，那种说不出来的感觉让我觉得很幸福也很感动。一个老师，叫学生端正学习姿势，是一件很平常的事情，可又有几个老师在学生写作业时帮学生端正了本子？又有几个老师在关注学生成绩外，又关心着学生的身体呢？我想起在家写作业时，母亲总会把我的本子轻轻端正。现在，生物老师给了我一种母亲在身边的温暖。
看着生物老师坐在讲台上写着备齐笔记，一阵阵感动涌上心头，我感觉有一束阳光倾洒在我的身上。
元旦前的一节生物课上，生物老师说：“新的一年即将到来，你们长大了一岁，而我又老了一年，哎！”老师故意做出那种很伤心的表情。同学们说：“老师您青春永驻！永远美丽！”全班都笑了起来。老师说：“在你们班上课，我觉得很温暖。”其实，生物老师您知道吗，上您的课，我们也感觉很温暖，真的！
班上每人出了一点钱买了些小礼物作为元旦送给了老师。送给生物老师的是一副手套。在板书的时候，生物老师的手就不会太冷，因为那上面载满了全班对生物老师的热爱。老师收到礼物的，特感动的说：“谢谢你们。也希望大家元旦快乐！”
教室里，同学们和生物老师都笑得很开心，这是一节温暖的晚自习。
生物老师仿佛有一根魔力棒，要不然和我们的关系怎么会这么好？魔力就来源于她那颗热爱学生的心。敬爱的生物老师，愿您的笑容永远留在您的脸上。
微生物介绍500字作文【六】
功能： ① 调节物质进出原生质体；
② 协调细胞壁物质的合成和组装；
③ 进行植物激素和与细胞生长、分化有关的环境信号的转导。
流动镶嵌模型突出了膜的流动性和不对称性，认为细胞膜由流动的脂双层和嵌在其中的蛋白质组成。磷脂分子以疏水性尾部相对，极性头部朝向水相组成生物膜骨架，蛋白质或嵌在脂双层表面，或嵌在其内部，或横跨整个脂双层，表现出分布的不对称性。
微生物介绍500字作文【七】
1：细胞周期：一次细胞分裂中期到下一次分裂中期的全部历程。包括：分裂间期和分裂期两个阶段。
2：分裂间期：前一次分裂结束到下一次分裂开始的一段时间。包括：复制前期、复制期和复制后期。
3：细胞分裂的三种形式：有丝分裂，减数分裂，无丝分裂。
4：有丝分裂：
特点：1）多数发生在植物体细胞中。
2）两个过程：一是核分裂，二是胞质分裂。
3）分裂后形成两个新的完整的细胞，与原细胞相同。主要作用是生长发
育和新陈代谢 。
5：减数分裂：
特点：1）与有性生殖有关，多数发生在性细胞中，分裂后产生生殖细胞。
2）细胞连续分裂两次;DNA复制一次。
3）一个母细胞分裂两次产生4个子细胞。
4）染色体数目减半。
