ch 4 extensions of mendelian inheritance Flashcards
mendelian inheritance
a pattern of inheritance that follows mendel’s laws; this pattern involves the transmission of eukaryotic genes that are located on the chromosomes found within the cell’s nucleus
simple mendelian inheritance
an inheritance pattern involving simple, dominant/recessive relationship that produces observed ratios in the offspring that readily obey mendel’s laws
wild-type alleles
an allele that is fairly prevalent in a natural population, generally found in more than 1% of the population; for polymorphic genes, there is more than one wild-type allele
genetic polymorphism
when two or more alleles occur in population; each allele is found at a frequency of 1% or higher
mutant allele
an allele that has been created by altering a wild-type allele by mutation
gain-of-function mutations
a mutation that changes a gene product so that it gains a new or abnormal function
dominant-negative mutations
a mutation that produces an altered gene product that acts antagonistically to the normal gene product; shows a dominant pattern of inheritance
haploinsufficiency
the phenomenon in which an individual has only a single functional copy of a gene and that single functional copy does not produce a normal phenotype; shows a dominant pattern of inheritance
incomplete penetrance
a situation in which an allele that is expected to cause a particular phenotype does not
expressivity
the degree to which a trait is expressed; for example, flowers with deep read have a high expressivity of the red allele
temperature-sensitive allele
an allele for which the resulting phenotype depends on the environmental temperature
incomplete dominance
a pattern of inheritance in which a heterozygous that carries two different alleles exhibit a genotype that is intermediate to those of the corresponding homozygous individual; a heterozygous may have pink flowers, whereas the homozygous have red or white flowers
overdominance (heterozygote advantage)
an inheritance pattern in which a heterozygous has greater reproductive success than either of the corresponding homozygous
multiple alleles
two or more alleles of the same gene found within a population
codominance
a pattern of inheritance in which two alleles are both expressed in the heterozygous condition; for example, a person with the genotype IA and IB has the blood type AB and expresses both surface antigens A and B
x-linked inheritance
an inheritance pattern in certain species that involves genes that are located only on the X chromosome
hemizygous
indicates that a male had a single copy of an x-linked gene; a male mammal is said to be hemizygous for x-linked genes
x-linked recessive
an inheritance pattern in which a gene is found on the x-chromosome and the disease-causing allele is recessive relative to a corresponding dominant allele
reciprocal cross
a pair of crosses in which the traits of the two parents differ with regard to sex; for example, one cross could be a red eyed female fly and a white eyed male fly the reciprocal cross would be a red eyed male fly and a white eyed female fly
sex-linked genes
gene that is located on only one of the chromosomes
y-linked genes (holandric genes)
genes (or alleles of genes) that are located only on the y chromosome
pseudoautosomal inheritance
the inheritance pattern of genes that are found on both the x and y chromosomes; even though such genes are located physically on the sex chromosomes, their pattern of inheritance is identical to those of autosomal genes
sex-influenced inheritance
an inheritance pattern in which an allele is dominant in one sex but recessive in the opposite sex
sex-limited inheritance
an inheritance pattern in which a trait is only found in one of the two sexes (ie beard development)
