W4: Pedigree analysis & Punnett Squares

Question 1

3 examples of autosomal recessive disorders

Answer 1

Cystic fibrosis
Sickle cell disease
Tay-Sachs disease

Question 2

Are lethal recessive alleles more or less common than lethal dominant alleles? Why?

Answer 2

Lethal RECESSIVE alleles are more common
- The lethal dominant allele only lasts one generation and is not transmitted. Whereas, the recessive lethal allele might not immediately manifest the phenotype of death

Question 3

Normal and Lethal example of Dominant (DD or Dd) inherited disorders

Answer 3

• Normal disorder - achondroplasia (dwarfism); 1/10000 people
• Lethal disease - Huntington’s disease
  
  • Late onset, already reproduced before lethal

Question 4

Is Hungtinton’s disease autosomal dominant or recessive?

Answer 4

Autosomal dominant

Question 5

How to distinguish if pedigree or dominant or recessive

Answer 5

1. If two affected people have an unaffected child, it must be dominant
2. If two unaffected people have an affected child, it must be recessive
3. If every affected person has an affected parent, it is dominant