文档介绍：Chapter 2 Mendel’s Law: The Basic Principles of Inheritance 第二章孟德尔遗传规律
Monohybrid crosses: The principle of segregation
Dihybrid crosses: The principle of independent assortment
Extensions of Mendel’s laws
Formulating and testing ic hypotheses
Mendelian Principles in Animals
Mendel’s study of heredity
His parents were farmers in Moravia, then a part of the Hapsberg Empire in Central Europe
At the age of 21, Mendel left the farm and entered a Catholic monastery in the city of Brünn
In 1847 he was ordained a priest, taught at the local high school, taking time out between 1951 and 1953 to study at the University of Vienna
After returning to Brünn, he resumed his life as a teaching monk and began his experiment with garden pea
In 1865, Mendel presented his results before the local Natural History Society
孟德尔选择豌豆作为杂交材料的原因
豌豆的形状和色泽极易区分和分析;豌豆
为自花授粉植物,易于杂交。
The garden pea
One peculiarity of pea reproduction is that the petals of the
flower close down tightly, preventing pollen grains from
entering or leaving. This enforces a system of self-fertilization
Each variety of peas are distinguished by a particular
characteristic. Mendel’s focus on these singular differences
between pea strains allowed him to study the inheritance of
one trait at a time.
Mendel eeded because he focused his attention on
contrasting differences between plants
孟德尔试验成功的原因
前人的试验有两个问题:没有对杂交子代按性状分类计数和没有运用统计分析
孟德尔成功之处在于:运用假说-推理方法,注意实验材料的选择,引入群体分析和数量统计分析
Monohybrid crosses: The principle of segregation 分离定律
Homozygous×Homozygous
All F1 offspring
are heterozygous
and purple color.
Ratio of 1:2:1
Tall and dwarf
varieties are
crossed-fertilized
All progeny
are tall.
Tall 3:
Dwarf 1
Mendel’s explanation for segregation 对分离现象的解释
Inheritant traits are determined by genes 遗传性状由基因决定
There are a pair of genes controlling a trait in a cell体细胞中有两个基因控制一个性状
A pair of gene segregate from each other during the formation of gametes 在性细胞形成中成对的基因彼此分离
Each gamete carries an allele 每个性细胞含一个基因
bina