Mendelian genetics helps us understand how traits and genetic disorders are passed down from parents to their children. The ideas behind this come from Gregor Mendel, who discovered three main principles: dominance, segregation, and independent assortment.
Mendelian genetics looks at disorders that happen because of changes in just one gene. Here are two examples:
Cystic Fibrosis: This disorder is caused by a change in the CFTR gene on chromosome 7. It is an autosomal recessive disorder, which means you need two copies of the mutated gene to be affected. About 1 in 25 people of European descent carry one copy of this gene.
Huntington's Disease: This is an autosomal dominant disorder, meaning only one copy of the mutated gene is needed to be affected. The gene is on chromosome 4, and about 1 in 10,000 people have this mutation. If a person has the gene, there is a 50% chance they will pass it to their children.
Autosomal Dominant: Usually, if someone has the disorder, at least one of their parents also has it. Huntington's is a good example of this type.
Autosomal Recessive: In this case, both parents must carry the gene for their child to be affected. For instance, if two parents are carriers of the Cystic Fibrosis gene, there is a 25% chance their child will have the disorder.
To predict the chances of having certain traits or disorders, we can use Punnett squares. For example, if two heterozygous parents (Bb) have children, we expect the following genetic makeup:
By understanding these principles, families dealing with genetic disorders can get better advice and understand their risks.
Mendelian genetics helps us understand how traits and genetic disorders are passed down from parents to their children. The ideas behind this come from Gregor Mendel, who discovered three main principles: dominance, segregation, and independent assortment.
Mendelian genetics looks at disorders that happen because of changes in just one gene. Here are two examples:
Cystic Fibrosis: This disorder is caused by a change in the CFTR gene on chromosome 7. It is an autosomal recessive disorder, which means you need two copies of the mutated gene to be affected. About 1 in 25 people of European descent carry one copy of this gene.
Huntington's Disease: This is an autosomal dominant disorder, meaning only one copy of the mutated gene is needed to be affected. The gene is on chromosome 4, and about 1 in 10,000 people have this mutation. If a person has the gene, there is a 50% chance they will pass it to their children.
Autosomal Dominant: Usually, if someone has the disorder, at least one of their parents also has it. Huntington's is a good example of this type.
Autosomal Recessive: In this case, both parents must carry the gene for their child to be affected. For instance, if two parents are carriers of the Cystic Fibrosis gene, there is a 25% chance their child will have the disorder.
To predict the chances of having certain traits or disorders, we can use Punnett squares. For example, if two heterozygous parents (Bb) have children, we expect the following genetic makeup:
By understanding these principles, families dealing with genetic disorders can get better advice and understand their risks.