Genetic Pedigrees Flashcards
Define a Pedigree.
Chart showing the presence or absence of a tract within a family across generations.
Define a genotype.
Genetic make up of an organism.
Define a phenotype.
Physical characteristics of an organism.
Define a dominant allele.
Allele that is phenotypically expressed.
Define a recessive allele.
Allele that is only expressed in absence of a dominant allele.
Define an autosomal trait.
Trait that is located on an autosome.
Define a sex-linked trait.
Trait that is located on one of the two sex chromosomes.
Define homozygous.
Having 2 identical alleles for a particular gene.
Define heterozygous.
Having 2 different alleles for a particular gene.
State 2 features of an autosomal dominant pedigree.
Appears in both sexes (with equal frequency). Both sexes transmit to offspring. Does not skip generations. Parents must be heterozygous if unaffected offspring.
State 2 features of an autosomal recessive pedigree.
Appears in both sexes, with equal frequency. Tends to skip generations. If both parents unaffected and offspring affected.
State an example of an autosomal dominant condition.
Huntington’s Disease. Myotonic Dystrophy. Polydactyl. Di George’s Syndrome.
State an example of an autosomal recessive condition.
Cystic fibrosis. Sickle-cell anaemia. Tay-Sachs Disease. Gaucher’s disease. Alkaptonuria.
Define a X-linked Dominant condition.
If male shows trait as must daughters. An unaffected mother CANNOT have affected sons. More common in females.
State an example of an X-linked Recessive condition.
Haemophilia A. Red-green colour blindness.
