This definitions covers Key Definitions within Inherited Disorders for GCSE Biology. Genetic disorders, family pedigrees, and probability calculations It is section 5 of 10 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 5 of 10
Practice
25 questions
Recall
20 flashcards
Key Definitions
Cystic fibrosis: An inherited disorder caused by two copies of a recessive allele (ff) that produces a faulty CFTR protein, resulting in thick sticky mucus in the lungs and digestive system. It is the most common life-threatening genetic disorder in the UK.
Polydactyly: An inherited condition caused by a dominant allele (P) that results in extra fingers or toes. Only one copy of the allele is needed for the condition to appear. It is usually not harmful and can be surgically corrected.
Carrier: A heterozygous individual (Ff) who has one recessive allele for a condition but does not show any symptoms because the dominant allele is expressed. Carriers can pass the recessive allele to their children.
Recessive disorder: A genetic condition that is only expressed when an individual inherits two copies of the recessive allele (homozygous recessive). Both parents must carry the allele for a child to be affected.
Dominant disorder: A genetic condition caused by a dominant allele, so only one copy is needed for the condition to appear. An affected parent (Pp) has a 50% chance of passing it to each child.
Genetic screening: Testing an individual's DNA to determine whether they carry alleles for a particular genetic disorder. Can be carried out on embryos (pre-implantation), fetuses (prenatal), or adults (carrier testing).
Pre-implantation genetic diagnosis (PGD): A technique used during IVF in which cells from an embryo are tested for genetic disorders before it is implanted in the uterus, allowing only unaffected embryos to be selected.