Week 3 - Mendelian Genetics Flashcards
What is a phenotype?
A creature’s external/observable features
What are alleles?
Different versions of the same gene, i.e. blue eyes, brown eyes
What is the law of segregation?
Two alleles per cell for a particular trait separate independently into gametes.
What is the law of independent assortment?
The separation of pairs of alleles for each gene is independent of other genes (not all genes obey this rule)
What is a pure-breeding/pure line?
An organism that produces only one progeny (offspring) like themselves
What is incomplete dominance?
When alleles of a gene are not always clearly dominant or recessive, and the heterozygotes have an intermediate phenotype
Co-Dominance
A heterozygous organism displays the phenotype of both alleles of a single gene and is said to display codominance. Neither allele is dominant or recessive.
What is pleiotrophy?
Most genes have multiple phenotypic effects, a property called pleiotrophy.
What is epistasis?
A gene at one locus alters the phenotypic expression of a gene at a second locus. E.g. labrador’s coat colour is determined by two genes, whether the pigment is expressed and if expresses whether the pigment is brown or black.
What is polygenic inheritance?
Those that vary in a population along a continuum. An additive effect of two or more genes on a single phenotype. E.g. skin colour, height
What are some examples of autosomal recessive disorders?
Albinism, sickle cell disease, and cystic fibrosis.
What are some examples of autosomal dominant disorders?
Achondroplasia and Huntington’s disease
What are some examples of sex-linked recessive diseases?
Haemophilia, Duchenne muscular dystrophy
What is aminocentesis?
A type of genetic testing in which a sample of amniotic fluid can be taken starting at the 14th to 16th week of pregnancy.
What is Chorionic Villus Sampling?
A sample of chorionic villus tissue (placenta) can be taken as early as the 8th to 10th week of pregnancy.
