Mendelian Inheritance Notes Pt.3

Question 1

How many single-genes traits are known in humans?

Answer 1

6000

Question 2

What can be used to study inheritance?

Answer 2

Pedigrees

Question 3

Concepts of A Pedigree

Answer 3

• Every affected person has at least one affected parent
• Mating between affected person and unaffected person is
  effectively a testcross

Question 4

How to read a pedigree?

Answer 4

Square: Male
Circle: Female
Shaded symbol: Affected individual with the trait
Unshaded symbol: Unaffected individual

Question 5

Some more aspects of pedigrees for dominace

Answer 5

1. Affected children always have at least one affected parent
2. As a result, dominant traits show a vertical pattern of inheritance (The trait is seen in every generation.)
3. Two affected parents can produce unaffected children, if both parents are heterozygotes

Question 6

Some more aspects of pedigrees for recessivness

Answer 6

1. Affected individuals can be the children of two unaffected carriers, particularly as a result of consanguineous (between relatives) mating
2. All the children of two affected parents should be affected
3. Rare recessive traits show a horizontal pattern (The disease skips generations) of inheritance
4. May show a vertical pattern of inheritance if the trait is extremely common in the population