基因突变的分子机制与生物进化

在自然群体中发现的遗传变异和物种之间的差异是人们普遍熟知的。同时我们都知道,最原始的生命非常小而且简单,可现在却有     

"现代生物进化理论简介"一节课的教学设计

“现代生物进化理论简介”是现行高中《生物》(人教版)第7章“生物的进化”的中心内容。也是对以前学过的生物学知识综合运用并与后续一章“生物与环境”有一定联系的教学内容。教学大纲对这一节的要求是识记。在我们所见到的对这一节课的教学设计上,多数教师都是通过以讲授为主线进行教学活动     

"生命起源和生物进化"专题的复习建议

高中教材“生命起源和生物进化”一章 ,由于历史的原因 ,内容较单薄 ,观念较陈旧 ,课时较少 ,过去一直被视为“角落知识”,没有引起师生们足够的重视。但随着近年来 ,生物学科思想的发展 ,生物学课程观念的演变 ,这部分内容已愈来愈显现出其重要的科学价值、社会价值、人文价值、创新价值和能力价值。自 1999年高考实施“3+ X”以来 ,这部分内容已成为考查学生思维品质、科学方法、价值取向、人文素质的极好素材 ,成为高考命题的一个新观点。因此 ,师生需加强对此内容复习策略的研究。本文拟从复习方式、知识视野、学科思想、题型示例 4个…     

科学研究方法外显化 自主构建生物进化历程——八年级生物进化教学设计

以“生物进化的历程”教学为例,将生物进化研究方法作为主线,通过分解课前小组学习任务,学生课上汇报交流,总结研究方法之间的异同,从而认识到方法互为补充的意义。教师提供不同生物类群的结构一览表,学生再利用学习到的科学方法自主构建出生物进化的历程。将真实科学研究过程的研究方法外显出来,使生物进化的历程这种纵向的概念构建过程自主发生,提升学生的科学思维。     

生物进化的"溶源菌"关系演变进程

从免疫学角度分析了病毒与噬菌体建立的“溶源菌”关系．提出了生物进化中的“溶源菌”进程观点,对一些生物进化问题做出了新的解释,包括生物在进化历程中如何抵抗疾病危害、保存物种并繁衍后代,寒武纪大爆发,生物进化在一定范围内出现的不连续性,生物间基因组的“C值悖理”及“重复基因序列”的由来等。结合转基因技术的成熟运用,提出了新的生物进化关系式:B=A x．有利于进化理论的深化完善。     

"生物进化的重要证据——化石"的教学设计

初中阶段要帮助学生形成进化思想和理解进化理论,形成进化观点,作为生物进化直接证据的化石是重要的载体.在"生物进化的重要证据——化石"的教学中,通过挖掘化石与进化的关系,分解概念,以核心问题引领,搭建概念形成支架,帮助学生形成重要概念.观察化石、"地层书"为载体的系列学习活动,使学生经历了识别、判断、关联信息、筛选、验证...     

生物进化研究的回顾与展望

生物进化是自然科学的永恒之迷。随着历史的发展和科学的进步,生物进化思想从早期的萌芽,到自然选择学说、新达尔文主义,从现代综合理论,到分子进化的中性学说。再到新灾变论和点断平衡论等。当前,由于生物学各分支学科的飞速发展．它们就各自的研究对象在宏观和微观上不断地拓展和深入,并在不同的层次上形成了广泛的交叉、渗透和融合,现代的进化生物学研究从宏观的表型到微观的分子,从群体遗传改变的微进化到成种事件以及地史上生物类群谱系演化的宏进化,从直接的化石证据到基于形态性状、分子证据和环境变迁的综合推理,从基于遗传基础的比较基因组学到演化机理的进化发育生物学等。可以预见,在新的世纪里,在哲学和具体方法论(如系统论、控制论和信息论)的指导下,在生命科学、其他自然科学乃至社会科学工作者的通力合作下,综合遗传、发育和进化等研究领域的各种理论成果,生物进化理论即将出现也一定会出现的一个新的大综合和新的大统一。     

"现代生物进化理论的主要内容"复习课教学

在"现代生物进化理论的主要内容"高三一轮复习课教学中,以"装在试管里的进化"——大肠杆菌的进化研究为情境,通过材料探寻、经典实验分析及验证实验设计、概念图构建、知识应用等环节,引导学生自主回顾知识、建立知识框架,真正树立生物进化的观点和辩证唯物主义观点,同时提升科学思维、科学探究能力,加深对科学本质的理解和感悟.     

运用数学探究生物进化的实质

生物进化的实质是种群基因库基因频率在环境选择作用下的定向改变,这个变化过程.运用数学计算与分析,引导学生自主探究,深刻理解生物进化的实质.在计算、分析与讨论的合作交流过程中体验和尝试数学探究的过程和方法,建构知识、提高能力、丰富情感体验.     

Evolutional Genetics and Diseases of Civilization

Inclination for hyperinsulinemia that was formed in the human population at early stages of development and was fixed genetically in the process of evolution is suggested to underlie pathogenesis of the currently most widely spread diseases of the cardiovascular system (atherosclerosis and hypertension) as well as diabetes mellitus of the 2 type and obesity that are concomitant with a high frequency. Under conditions of civilization, chronic hyperinsulinemia can develop in response to the regularly excessive nutrition. The consequence of the excessive food consumption and the chronic hyperinsulinemia can be overcrowding with lipids (triglycerides) of adipose tissue—the organism lipid store. The natural protective reaction of the cell that contains the limitedly possible amount of lipids is a decrease of the number of insulin receptors and development of insulin resistance. The insulin resistance, in turn, provides the appearance of hyper- and dislipoproteinemia alongside with hyperglycemia. One of the most clinically significant ways of achievement of homeostasis is storage of lipids in the arterial wall. Atherogenic and other concomitant metabolic disorders, specifically changes of blood coagulation properties providing susceptibility to hypercoagulation, affect the blood rheological properties and seem to lead to pathology of the entire vascular system: chronic venous insufficiency, disturbance of microcirculation, and arterial atherosclerosis. There is substantiated the natural interconnection of atherosclerosis, type 2 diabetes, obesity, and arterial hypertension that at present are accepted as the main clinical manifestations of the so-called “metabolic syndrome.” It is suggested that the basis for arterial hypertension might be disturbances of microcirculation leading to an increase of peripheral vascular resistance as well as insufficiency of renal blood supply at the level of arterial and microcirculatory bed.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 186–191.Original Russian Text Copyright © 2005 by Liberman.     

Evolutional and biological aspects of placentophagia

Over the last 30 years it could be observed that a very small minority of modern humans consumes the human placenta that belongs to the afterbirth. This behavior, which is known by the technical term of placentophagia, is the focal point of the present essay. Placentophagia is a behavior common among almost all kinds of mammals, even primates can be observed ingesting at least amniotic fluid during the birth. However, humans of traditional human cultures consume the afterbirth only in rare cases. In detail, the present essay discusses the hypothesis that human placentophagia has a phylogenetic basis and the hypothesis that human placentophagia is physiologically reasonable. It is concluded that the behavior of the human placentophagia neither possesses a phylogenetic basis nor can be regarded as physiologically reasonable.     

Perspective on Mutagenesis and Repair: The Standard Model and Alternate Modes of Mutagenesis

ABSTRACT

The basic ideas of replication, mutagenesis, and repair have outlined a picture of how point mutations occur that has provided a valuable framework for theory and experiment, much as the Standard Model of particle physics has done for our concept of fundamental particles. However, alternative modes of mutagenesis are being defined that are changing our perspective of the “Standard Model” of mutagenesis, requiring an expanded model. The genome is now envisioned as being in dynamic equilibrium between a multitude of forces for mutational change and forces that counteract such change. By maintaining a delicate balance between these forces, cells avoid unwanted or excessive mutations. Yet, cells allow mutagenesis to occur under certain conditions. We can define an emerging paradigm. Namely, mechanisms exist that can direct point mutations to specific designated genes or regions of genes. In some cases, this is achieved by specific enzymes, and in other cases high mutability is programmed into the sequence of certain genes to help generate diversity. In yet additional cases, general mutability is increased under stress, and selective forces allow the recovery of favorable mutants.     

The Construction and Use Of A Scale Model

Abstract

Scale models, constructed from simple, readily available materials are an excellent means of presenting archeological data to the general public.

Scale models of historic and prehistoric sites are one of the most graphic ways of presenting to the public some of the information acquired through arc heological investigation. A miniature reconstruction can be made with a very limited amount of equipment and materials.     

"Race" and the Construction of Human Identity

Race as a mechanism of social stratification and as a form of human identity is a recent concept in human history. Historical records show that neither the idea nor ideologies associated with race existed before the seventeenth century. In the United States, race became the main form of human identity, and it has had a tragic effect on low-status "racial" minorities and on those people who perceive themselves as of "mixed race." We need to research and understand the consequences of race as the premier source of human identity. This paper briefly explores how race became a part of our culture and consciousness and argues that we must disconnect cultural features of identity from biological traits and study how "race" eroded and superseded older forms of human identity. It suggests that "race" ideology is already beginning to disintegrate as a result of twentieth-century changes.