Gene Transmission and Inheritance Patterns | 基因的遗传传递方式与规律

📚 Gene Transmission and Inheritance Patterns | 基因的遗传传递方式与规律

Genetics is the study of how traits are passed from parents to offspring. The fundamental rules were first described by Gregor Mendel in the nineteenth century, and modern molecular biology has since revealed their physical basis in chromosomes and DNA. This article reviews the key patterns and laws of inheritance required for the CIE A-Level Biology syllabus.

遗传学是研究性状如何从亲代传递给子代的科学。孟德尔在19世纪首先描述了基本规律，现代分子生物学则进一步揭示了这些规律在染色体和DNA上的物质基础。本文系统复习 CIE A-Level 生物学大纲中关于基因遗传传递方式与规律的核心内容。

1. Foundations of Inheritance | 遗传的基本概念

A gene is a length of DNA that codes for a functional product, usually a protein. Alternative forms of the same gene are called alleles; they occupy the same locus on homologous chromosomes.

基因是一段编码功能性产物（通常是蛋白质）的DNA。同一基因的不同形式称为等位基因，它们位于同源染色体上的同一基因座。

An organism with two identical alleles is homozygous; with different alleles it is heterozygous. The visible or measurable effect is the phenotype, while the underlying allelic combination is the genotype. In complete dominance, only the dominant allele is expressed in the heterozygote.

具有两个相同等位基因的个体称为纯合子；具有两个不同等位基因的个体称为杂合子。可观察或可测量的性状表现称为表型，而其背后的等位基因组合称为基因型。在完全显性中，杂合子只表达显性等位基因。

2. Mendel’s Law of Segregation | 孟德尔分离定律

Mendel crossed pure-breeding tall and dwarf pea plants. All F₁ offspring were tall,

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