Gene Variants and Inheritance

In the picture

1. 1A red dot on a chromosome: a dominant variant of a gene.
2. 2A blue dot on a chromosome: a recessive variant of a gene.
3. 3A paired chromosome with two blue dots: two recessive variants, one from each parent.
4. 4A paired chromosome with one red and one blue dot: one dominant and one recessive variant.
5. 5A paired chromosome with two red dots: two dominant variants, one from each parent.

Examples

• Cystic fibrosis is usually inherited when a child gets two recessive disease variants, one from each parent.
• Huntington’s disease can appear when a child inherits one dominant disease variant from either parent.

Quiz: Gene Variants and Inheritance (Age 16)

1. 1

   According to the card, when do recessive gene variants usually cause a genetic disease?

   • Only when both inherited copies of the gene are recessive variants.
   • When one inherited copy is a recessive variant and the other is a dominant variant.
   • When only one inherited copy of the gene is a recessive variant.
2. 2

   According to the card, what is true if a child inherits one dominant variant and one recessive variant for a gene?

   • Neither variant can affect the child because only one dominant copy is inherited.
   • The dominant variant can affect the child even though only one copy is inherited.
   • The recessive variant will always cause the disease because it is paired with a dominant variant.
3. 3

   According to the card, what affects whether a genetic disease appears in a child?

   • The versions of the gene that the child inherits from each parent.
   • Whether the child inherits the gene from only the mother or only the father.
   • Whether the parents are healthy or affected at the time of birth.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.