Science at a Distance

Mendelian Genetics

Lecture notes - Part 1 Lecture notes - Part 2

Lecture Notes

a check up

Use this department to check up on the accuracy of your lecture notes. Make sure that you have written down the following definitions, explanations and important concepts in your notes.

Mendel - Part Three

Independence of Traits

Mendel observed that one trait (such as flower color) was independent of a second trait (such as seed color).

Independent Inheritance of Traits - Starting Material

Mendel performed a series of experiments to show that the inheritance pattern of one trait (such as flower color) was independent of the inheritance pattern of a second trait (such as seed color, or plant height).

Two Factor Crosses - Round One

In the first round of crosses between plants differing in two traits Mendel took the pollen from one parent and used it to fertilize the egg cells of the second plant.

Two Factor Crosses - Round Two

During the second round of crosses, Mendel took the F1 plants with the heterozygous genotypes generated in round one, and crossed them again to produce the F2 generation.

Growing the F2 Generation

Mendel grew the seeds that would give him the F2 generation. When the plants were fully mature he examined all the phenotypes, and found some new ones.

Sex Determination

Long after Mendel and his work, other scientists began work on the genetic determination of other traits. One of these traits was sex gamete production, how it is controlled and how it is determined.

The X and Y Chromosomes

In humans and fruit flies, the genetic determination of sexual identity involves whole chromosomes.

Sex Inheritance

During meiosis, the sex chromosomes (X and Y) pair and are separated into different gametes. Fusion of two gametes at the time of fertilization produces a zygote, who's sex is determined by the combination of chromosomes inherited.

Sex-linked Traits

In humans, the X chromosome carries some genes that are not found on the Y chromosome. Inheritance of the phenotypic traits determined by these genes is therefore linked to the sex of the individual.

The Inheritance of Sex-linked Traits

The pattern of inheritance of genes and traits carried by the X chromosome closely follows the inheritance of the sex of the individuals.

Test Yourself with Quick Check Number MG-3025
Lecture Notes - Part 1 Lecture Notes - Part 2
Mendelian Genetics - Topic Outline
Science at a Distance
© 1997, Professor John Blamire