Chapter 3 - Other types of inheritance Flashcards
What are sex chromosomes
They carry the genes that code for structural and functional proteins involved in determining the sex of an individual
Autusomes
Chromosomes not involved with determining sex
What are the two sets of chromosomes found?
Female = X (longest in human genome)
Male = Y (shortest)
What is a sex-linked character?
Any character controlled by a gene located on a sex chromosome.
Most are found on X chromosome because it is long = X-linked genes.
Male = Y-linked genes
What is a well-known X-linked disease?
Haemophilia
What is haemophilia?
A person cannot produce proper functioning clotting proteins in their blood
What allele must be present for a person with haemophilia?
Haemophilia is coded by a recessive allele
A person cannot have a dominant allele
Which gender can be the only carrier for haemophilia?
Females
What does it mean to be a carrier?
Heterozygous for a recessive disorder. They don’t have the phenotype but can possibly pass it to their offspring.
What do males require to show haemophilia
one copy of the recessive allele
What is discrete variation
Character controlled by a single gene and produced distinct and a finite number of different phenotypes
What is polygenic?
Character controlled by the interaction of more than one gene. Multiple genes work together for a single character.
What is polygenic inheritance?
Characters that show continuous variation in the phenotype like colours in hair, skin and eye.
What is continuous variation?
More than two or three different phenotypes for the same character
How do we determine polygenic phenotypes?
The presence of every dominant allele increases the production of pigment.
More pigment = darker colour phenotype.
