3.4 Inheritance


 
Inheritance: important terms
In this introductory video, we have a look at the most important terms relating to the topics inheritance.


 
Types of crosses
This video gives an overview of the different types of crosses, such as autosomal dominant, recessive, sex-linkage and co-dominance.


 
Monohybrid crosses
Monohybrid crosses are also known as single-factor crosses.


 
Autosomal recessive inheritance
Here a condition is passed on on a non-sex chromosome. The condition is expressed, if two recessive alleles are present.


 
Autosomal dominant inheritance
Here a condition is passed on on a non-sex chromosome. The condition is expressed, even if only one allele is present (heterozygous).


 
Co-dominance
The inheritance of blood groups (ABO system) is an example of a co-domnant inheritance and multiple alleles.


 
Test cross
A test cross takes place when an organism with an unknwn genotype (Rr or RR) is crossed with an organism of a known genotype (rr). Based on the offspring, the genotype of the parents can be deduced.


 
Sex linkage
Here an allele is present on a sex chromosome, usually the X-chromosome.


 
Pedigree analysis
A pedigree is a graphical representation of a family tree. It is possible to deduce the genotype of individuals based on the pedigree diagram.