4.6.1.7 Inherited Disorders

Question 1

How do people get certain disorders?

Answer 1

• some disorders are inherited
• genetic disorders are caused by inheriting certain alleles

Question 2

Polydactyly:

Answer 2

having extra fingers or toes

Question 3

What is polydactyly caused by?

Answer 3

caused by a dominant allele

Question 4

Cystic fibrosis:

Answer 4

a disorder of the cell membrane which results in thick mucus in the airways and pancreas

Question 5

What is cystic fibrosis caused by?

Answer 5

• caused by a recessive allele
• both parents need to either be carriers (having one of the recessive alleles) or one must have CF themselves and the other is carrier

Question 6

Embryonic screening:

Answer 6

• a procedure used to determine the presence of faulty genes in an embryo mainly through IVF
• a few embryonic cells are removed and screened for defective alleles

Question 7

What can embryonic screening allow scientists to do?

Answer 7

embryonic screening allows scientists to observe whether the child will have a genetic condition or not

Question 8

How can embryonic screening take place?

Answer 8

• if the embryo is developed in the lab, cells can be taken from it and analysed
• DNA from embryos in the womb can be extracted
• embryos can be extracted from the womb

Question 9

Arguments for embryonic screening:

Answer 9

• reduces the number of people suffering with a disability/disorder (ethical)
• treating disorders is very expensive (economic)
• there are many regulations in place to stop embryo screening for certain traits getting out of hand (social)
• identifies embryos with a genetic disorder

Question 10

Arguments against embryonic screening:

Answer 10

• could encourage people to pick/change characteristics that would not have had a significant impact on the child - creating designer babies (ethical)
  - embryo selection for social reasons e.g. sex rather than health
• expensive to carry out screening (economic)
• may promote prejudice as it suggests that those with genetic disorders don’t have the ability to live a full life or are unwanted (social)
• decisions about terminating a pregnancy have to be made (social)
• the procedure can lead to a miscarriage (social)

Question 11

Process of embryo screening:

Answer 11

• DNA isolated from embryo
• fluorescent probe mixed with embryo DNA
• probe then binds with embryonic DNA
• UV light used to show alleles which cause genetic disorders