Discovery of discrete inherited units The existence of discrete inheritable units was first suggested by Gregor Mendel (1822–1884). From 1857 to 1864, in Brno (Czech Republic), he studied inheritance patterns in 8000 common edible pea plants, tracking distinct traits from parent to offspring. He described these mathematically as 2n combinations where n is the number of differing characteristics in the original peas. Although he did not use the term gene, he explained his results in terms of discrete inherited units that give rise to observable physical characteristics.
Charles Darwin developed a theory of inheritance he termed pangenesis, from Greek pan ("all, whole") and genesis ("birth") / genos ("origin").[6][7] Darwin used the term gemmule to describe hypothetical particles that would mix during reproduction.
Specifically, in 1889, Hugo de Vries published his book Intracellular Pangenesis, in which he postulated that different characters have individual hereditary carriers and that inheritance of specific traits in organisms comes in particles. De Vries called these units "pangenes" (Pangens in German), after Darwin's 1868 pangenesis theory.
Discovery of DNA Advances in understanding genes and inheritance continued throughout the 20th century. Deoxyribonucleic acid (DNA) was shown to be the molecular repository of genetic information by experiments in the 1940s to 1950s.[12][13] The structure of DNA was studied by Rosalind Franklin and Maurice Wilkins using X-ray crystallography, which led James D. Watson and Francis Crick to publish a model of the double-stranded DNA molecule whose paired nucleotide bases indicated a compelling hypothesis for the mechanism of genetic replication.
In the early 1950s the prevailing view was that the genes in a chromosome acted like discrete entities, indivisible by recombination and arranged like beads on a string. The experiments of Benzer using mutants defective in the rII region of bacteriophage T4 (1955-1959) showed that individual genes have a simple linear structure and are likely to be equivalent to a linear section of DNA.
Collectively, this body of research established the central dogma of molecular biology, which states that proteins are translated from RNA, which is transcribed from DNA. This dogma has since been shown to have exceptions, such as reverse transcription in retroviruses. The modern study of genetics at the level of DNA is known as molecular genetics.
In 1972, Walter Fiers and his team were the first to determine the sequence of a gene: that of Bacteriophage MS2 coat protein.[18] The subsequent development of chain-termination DNA sequencing in 1977 by Frederick Sanger improved the efficiency of sequencing and turned it into a routine laboratory tool. An automated version of the Sanger method was used in early phases of the Human Genome Project.
离散继承单元的发现 离散遗传单元的存在最早是由格里高尔·孟德尔(1822-1884)提出的。从1857年到1864年，在捷克共和国的Brno，他研究了8000种常见的可食用豌豆的遗传模式，追踪从父母到后代的不同特征。他在数学上把这些描述为2n种组合，其中n是原始豌豆中不同特性的数量。虽然他没有使用“基因”这个词，但他用离散的遗传单元来解释他的结果，这些单元产生了可观察到的物理特征。
查尔斯·达尔文发展了一种他称之为泛生论的遗传理论，来自希腊语pan(“全，全”)和genesis(“诞生”)/ genos(“起源”)。达尔文用gemmule这个词来描述在繁殖过程中可能混合在一起的假想粒子。
具体来说，1889年Hugo de Vries出版了他的《细胞内泛生论》一书，在书中他假定不同的性状具有个体的遗传载体，并且生物体中特定性状的遗传是以粒子的形式存在的。德弗里斯根据达尔文1868年的泛生论将这些单位命名为“泛生体”。
发现DNA的 20世纪，基因和遗传的研究不断取得进展。脱氧核糖核酸(DNA)在20世纪40 - 50年代的实验中被证明是遗传信息的分子仓库。Rosalind Franklin和Maurice Wilkins利用x射线晶体学研究了DNA的结构，James D. Watson和Francis Crick发表了一个双链DNA分子模型，其配对的核苷酸碱基为基因复制机制提供了一个令人信服的假设。
在20世纪50年代早期，流行的观点是染色体上的基因表现得像离散的实体，不能被重组分割，排列得像一串珠子。Benzer利用噬菌体T4 rII区缺陷突变体进行的实验(1955-1959)表明，单个基因具有简单的线性结构，可能相当于DNA的线性片段。
总的来说，这一研究体系确立了分子生物学的中心教条，即蛋白质是从RNA翻译而来的，而RNA是从DNA转录而来的。这一理论后来被证明是有例外的，例如逆转录病毒的逆转录。现代遗传学在DNA水平上的研究被称为分子遗传学。
1972年，Walter Fiers和他的团队首次确定了一个基因的序列:噬菌体MS2外壳蛋白的序列。1977年，Frederick Sanger开发了链终止DNA测序，提高了测序效率，使之成为实验室的常规工具。在人类基因组计划的早期阶段使用了Sanger方法的自动化版本。