谈系谱分析中的一个概率问题

人类遗传学中常涉及到系谱分析问题。通过对某个家系的遗传分析,不仅可以了解这个家系中各个成员的基因型分布情况,而且还可估计他们婚配后所生子女出现各种基因型的概率,因此,系谱分析与概率分析有着密切的关系,如果对这类问题不加注意,很容易得出错误结论。特别当...     

个体运动的病毒传播行为模拟

提出了一个基于二维规则网格的SIS(Susceptible-Infected-Susceptible)动态疾病传播模型,并用元胞自动机方法进行计算机模拟,考查该模型中感染概率、治愈概率、人群密度及人群的流动对疾病传播的影响,结果表明,系统的稳态感染比例随感染概率和人群密度的增加而增大,随治愈概率的增加而减小,同等条件下流动人群比静止人群更容易传播疾病,根据这些研究结论最后给出了对应的疾病预防和控制措施。     

遗传分析中的相关计算

遗传概率的计算也许是许多考生头痛的一个问题,花了很长时间,最后计算出来的概率还是不正确,现在我们一起来探讨遗传中的几种计算概率的题型的解题思路和方法。     

应用贝叶斯理论推断DNA分子标记基因型

引入贝叶斯理论用以从DNA分子标记的表现型（电泳谱带）推断其基因型（DNA来源）。结果表明,根据标记座位独立贫富而确定的遗传信息不完全标记的基因型概率,与根据令近的遗传信息完全标记的基因型和有关重组率算得的相应贝叶斯概率,通常都有很大的差异,所以在进行数量性状基因定位和标记辅助选择等工作之前,应当计算每一个体基因组上所有遗传信息不完全座位的有关基因型的贝叶斯概率。文中列出计算未知基因型的贝叶期概率的详细过程,也讨论了贝叶斯概率的若干推广应用。     

多项选择题解题概率初步分析——以部分执业资格考试为例

多项选择题是执业资格考试常见的题型之一,应试难度较大。部分考试辅导机构和个人也根据考试经验进行总结,提出"宁缺勿滥"的建议,做定量分析的很少。笔者根据自己的应考经验及对历年考题的分析,运用客观概率法和主观概率法进行量化研究,验证了"宁缺勿滥"的建议,同时也得出了解题时主观概率的参考标准。     

对两个概率计算问题的分析

在概率计算中经常遇到这样一类问题:双亲为杂合子,产生了1个显性性状的个体,如果这一个体再与另一显性性状的个体交配,求所得后代的表现型概率。针对这一问题,在计算中可能会出现各种错误,下面对其进行具体讨论。例1 某种常染色体上的隐性遗传病在人群中的发病率为1／2 500。有1对夫妇均正常,其中一方的母亲是该病患者,请问,这对夫妇的子女患该种遗传病的可能性有多大?     

二项分布在遗传学概率计算中的应用

二项分布是概率论中描述离散型随机变量的一个理论分布。举例介绍了二项分布在遗传学概率计算中的重要应用。     

明确遗传学中的几个概率统计问题

遗传学教学中常用到概率统计知识,这对学生分析试验数据,掌握遗传规律是非常必要的。我们在教学中,感觉到有的教科书中对一些概率统计问题的提法并不恰当,或是不符合概率统计原理,或是引起学生误解,在此笔者提出几点看法,与各位教师商榷。     

小议遗传概率的计算

所谓概率,就是在一定条件下某一独立事件或相关事件所能产生的理论上的比率,通称几率,即机会。概率可能发生,也可能不发生。因此,概率是随机的,而不是固定的。概率只能大于或等于0,或者是小于或等于1。即概率只能在0与1之间。近几年,我在高中生物教学和复习过程中,根据概率的概念与基本定律,对常见的三种类型遗传几率的计算题的解题的思路、分析和方法步骤,给学生进行了讲述,收到较好的效果。一、单一的基本事件的概率的计算,即亲本只存在一种基因型时子代发生某一基因     

运用公式求算两种遗传病的概率

遗传病概率计算是高中生物学教学的一个重点和难点。学生一般能熟练地进行一种遗传病概率的求算 ,而对两种遗传病概率的求算则感到十分困难。笔者在实际教学中 ,首先帮助学生总结归纳出求算两种遗传病概率的一般公式 ,然后应用公式解题 ,从而使计算简易准确 ,极大地调动了学生的学习积极性 ,收到了较好的教学效果。下面简述公式的归纳过程及其应用。1　公式的归纳1.1　首先研究一种遗传病的有关情况 ,下面以白化病遗传为例 :表 1亲本子代基因型及比例 子代表现型及比例肤色正常 ( A )白化 ( aa)AA×aa 1Aa 10Aa×Aa 1/ 4AA· 2 / 4Aa· …     

Combining Population Viability Analysis with Decision Analysis

Management of endangered species requires methods to assess the effects of strategies, providing a basis for deciding on a best course of action. An important component of assessment is population viability analysis (PVA). The latter may be formally implemented through decision analysis (DA). These methods are most useful for conservation when used in conjunction. In this paper we outline the objectives and the potential of both frameworks and their overlaps. Both are particularly helpful when dealing with uncertainty. A major problem for conservation decision-making is the interpretation of observations and scientific measurements. This paper considers probabilistic and non-probabilistic approaches to assessment and decision-making and recommends appropriate contexts for alternative approaches.     

Immunoblot Analysis

Immunoblotting (western blotting) is a rapid and sensitive assay for the detection and characterization of proteins that works by exploiting the specificity inherent in antigen-antibody recognition. It involves the solubilization and electrophoretic separation of proteins, glycoproteins, or lipopolysaccharides by gel electrophoresis, followed by quantitative transfer and irreversible binding to nitrocellulose, PVDF, or nylon. The immunoblotting technique has been useful in identifying specific antigens recognized by polyclonal or monoclonal antibodies and is highly sensitive (1 ng of antigen can be detected). This unit provides protocols for protein separation, blotting proteins onto membranes, immunoprobing, and visualization using chromogenic or chemiluminescent substrates.Download video file.^{(92M, mov)}     

Canonical Analysis

Several fundamental properties of canonical variates are developed. In addition, the equivalence of the redundancy coefficient and the composite coefficient of determination is demonstrated; the latter is used in evaluating the prediction of input variables by canonical variates.     

Phosphoproteome Analysis

Protein phosphorylation is directly or indirectly involved in all important cellular events. The understanding of its regulatory role requires the discovery of the proteins involved in these processes and how, where and when protein phosphorylation takes place. Investigation of the phosphoproteome of a cell is becoming feasible today although it still represents a very difficult task especially if quantitative comparisons have to be made. Several different experimental strategies can be employed to explore phosphoproteomes and this review will cover the most important ones such as incorporation of radiolabeled phosphate into proteins, application of specific antibodies against phosphorylated residues and direct staining of phosphorylated proteins in polyacrylamide gels. Moreover, methods to enrich phosphorylated proteins such as affinity chromatography (IMAC) and immunoprecipitation as well as mass spectrometry for identification of phosphorylated peptides and phosphorylation sites are also described.     

Phylogenetic Analysis of Burkholderia Species by Multilocus Sequence Analysis

Burkholderia comprises more than 60 species of environmental, clinical, and agro-biotechnological relevance. Previous phylogenetic analyses of 16S rRNA, recA, gyrB, rpoB, and acdS gene sequences as well as genome sequence comparisons of different Burkholderia species have revealed two major species clusters. In this study, we undertook a multilocus sequence analysis of 77 type and reference strains of Burkholderia using atpD, gltB, lepA, and recA genes in combination with the 16S rRNA gene sequence and employed maximum likelihood and neighbor-joining criteria to test this further. The phylogenetic analysis revealed, with high supporting values, distinct lineages within the genus Burkholderia. The two large groups were named A and B, whereas the B. rhizoxinica/B. endofungorum, and B. andropogonis groups consisted of two and one species, respectively. The group A encompasses several plant-associated and saprophytic bacterial species. The group B comprises the B. cepacia complex (opportunistic human pathogens), the B. pseudomallei subgroup, which includes both human and animal pathogens, and an assemblage of plant pathogenic species. The distinct lineages present in Burkholderia suggest that each group might represent a different genus. However, it will be necessary to analyze the full set of Burkholderia species and explore whether enough phenotypic features exist among the different clusters to propose that these groups should be considered separate genera.