Gene Therapy Summary (A-Level 2nd Year)

Gene Therapy


 Genes code for proteins + they give rise to characteristics (working enzymes, petal
colours
 Alleles are different versions of the same gene (proteins) = (variety of petal colours)
 Recessive alleles code for non-functioning protein
 Homozygous dominant + heterozygous have at least 1 allele that codes for a
functioning protein
 Homozygous recessive – no alleles code for functioning protein, so non-function
protein made.
 Genetic disorders can be caused by both dominant + recessive alleles (mostly
recessive alleles cause genetic diseases)



What is Gene Therapy + How it works?
 Medical treatment for genetic disorders that alters/replaces allele that cause the
disorder.


If disorder is caused by….
 Recessive allele – dominant allele is added = cystic fibrosis
 Dominant allele – extra DNA inserted into allele to inactivate it = Huntington’s



Somatic vs germ line:
 Somatic (body) gene therapy = alleles altered in specific somatic cells (normal
body cells)
Vector = delivery mechanism for desired allele to get into cells of interest. Cells of interest
change depending on the genetic disease present.
 Vector injected into muscles = muscular dystrophy.


 Vector inhaled into respiratory system = cystic fibrosis

 Vectors introduced into blood stem cells/bone marrow transplant = scid




 Germ line gene therapy = alleles altered in gametes