Fig. 2.2

Mendel’s breakthrough:

Patterns, particles, and principles of heredity

1822-1884

Syllabus

Genetics1. Structure and function of genes.

2. How genes are transmitted from cells to cells, parents to children?

3. How phenotypes are controlled by the genotypes?

Fig. 2.4

Fig. 2.7

A new experimental approach

A new experimental approach

1. Garden pea: self-fertilization or cross-fertilization, and large number of individuals within a relatively short

growing seasons.

2. Mendel examined the inheritance of clear-cut alternative forms.

3. Mendel collect pure-breeding lines, which produce offspring carrying specific parental traits that remain constant form generation to generations.

4. To control mating, to ensure that the progeny he observed really resulted from the special fertilization he intended.

5. Mendel worked with large numbers of plants.

Fig. 2.8a

Fig. 2.9

Monohybrid crosses reveal units of inheritance and

the law of segregation

1866, Experiment on plant hybrids

recessivedominant

Every plant carries two copies of a unit of inheritance (genes),

Each gene comes in alternative forms (alleles).

Fig. 2.11

Punnett square

The Law of Segregation

• The law of segregation: alleles separate during gametes formation, and re-unit randomly at fertilization.

Fig. 2.15

Dihybrid crossed revealsthe law of independentassortment

Fig. 2.16 The law of independent assortment

Mendel’s work1. Explain the reappearance of hidden trait,

2. Disprove the idea of blended inheritance

3. Show the mother and father make an equal genetic contribution to the next generation.

4. Deduced two basic rules of gene transmission.

Blended inheritance

Patent trait become mixed and forever changed in the offsprings

Old misconceptions about heredity

Fig. 2.19

The science of genetics begins with the rediscovery of Mendel

Mendelian inheritance in Humans

Table 2.1

囊腫纖維症

囊腫纖維症

苯酮尿症

Fig. 2.20

A vertical pattern of inheritance indicates a rare dominant trait

Huntington disease

Pedigree:A family history

Fig. 2.21

A horizontal pattern of inheritance indicates a rare recessive trait

Cystic fibrosis