Extensions of Mendelian inheritance Flashcards
Incomplete Dominance
The domiant alles isnt completely express when the recessive allele is around & get a mixture of the domiant & recessive allele (ex. breeding a red flower with a white flower & getting a pink flower)
Incomplete Penetrance
People with the genotype may not always express the phenotype (Lower the penetrance less likely you would express it)
Overdominance
When a heterozyogte has an extreme phenotype than either of its parents
(ex. Sickle cell anemia and malaria resistance)
Codominance
When both domiant alleles (genes) are expressed
(ex. ABO blood types)
X-Linked
- Inheritance of gene which is located on X-chromosome
- Male has only one copy of the gene (hemizygous), female has two copies of the gene
(ex. Color blindness)
Sex Influenced
- Effect of sex on the phenotype ( one allele may be dominant in male but recessive in female)
- Sex hormone may regulate gene expression pattern
(male blindenss)
Sex Limited
- Certain trait is shown only one gender
- Sex hormone that is produced from only one gender is essential on producing a particular phenotype
(ex. Gender specific traits)
Lethal Allele
- An allele which is responsible for death of an organism
- Mutated protein from lethal allele may cause detrimental effect to the organism
- In a case of loss-of-function allele, recessive homozygote causes lethal effect to an organism
Wild Type Allele
- Produces functional protein which exerts normal/usual trait
- There may be more than one wild-types (especially phenotypically)
Mutant Allele
Other than wild-type allele that exerts different trait than normal one & May cause polymorphism (various phenotypes) & also May show altered level of protein expression or abnormal protein
Recessive Allele
Character of the allele is masked by the function of dominant allele
Dominant Allele
Presence of one copy of the allele is enough to exert a trait
(Produces enough protein to express phenotype)
Gain-of-function mutation
Mutant gains a new or abnormal function
Dominant-negative mutation (antimorphic mutation)
Encodes a protein that acts antagonistically to the normal protein & Mutated gene product may bind to normal gene product and inactivate the function
Haploinsufficiency
Only one copy of the gene is functional but which is not enough to exert normal phenotype
(ex. Polydactyly)
Gene redundancy
Phenomenon that one gene can compensate for the loss of function of another gene
Causes of gene redundancy
Gene duplication (and subsequent mutations) & Paralogs are duplicated genes that are different due to accumulated mutations
Epistasis
Gene-to-gene interaction where one gene determine if the other gene will be expressed
In Epistatic the gene its phenotype is __________
Expressed
In hypostatic the gene its phonotype is ___________
Supressed
Suppressor mutation
Second mutation of the gene which reverses the effect of the first mutation
Intergenic/extragenic suppressor
Second mutation is not on the same gene that caused phenotypic change by the first mutation
Complementation
A phenomenon in which the presence of two different mutant alleles in the same organism produces the wild type phenotype .
Holandric gene
A gene on the Y chromosome
Conditional Lethal Allele
An allele that is lethal but only under certain environmental conditions such as a temperature sensitive mutant
Gene Interaction
When two or more different genes influence the outcome of a single gene
Gene Knockout
When both copies of a normal gene have been replaced by an inactive mutant gene
Gene modifier effect
When the allele of one gene modifies the phenotypic effect of the allele of a different gene
Hemizygous
Describes the single copy of an X-linked gene in the male. A male mammal is said to be hemizygous for X linked genes
Intergenetic Supressor
A suppressor that is a different gene from the gene that contains the first mutation
Multiple Alleles
When the same gene exists in two or more alleles in a population
Nonessential Genes
Genes that are not absolutely required for survival, although they are likely beneficial
Pleiotrophy
The multiple effects of a single gene on the phenotype of an organism
Polymorphism
The prevalence of two or more phenotypic forms in a population, the phenomenon in which a gene exists in two or more alleles within a population
Reciprocal cross
A pair of crosses in which the traits of two parents differ in regard to sex. Example: red eyed female crossed with a white eyed male and the reciprocal cross would be a red eyed male fly and a white eyed female fly.
Recessive epistasis
A form of epistasis in which an individual must be homozygous for either recessive allele to mask a particular phenotype.
X linked recessive
An allele or trait in which the gene is found on the X chromosome and the allele is recessive relative to a corresponding allele
Semilethal alleles
Lethal alleles that kill some individuals but not all
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 that of autosomal genes.
Maternal effect
Genotype of the mother determines the phenotype of the offspring & the genotype of father or offspring are irrelevant to the phenotype
Polygentic traits
Mnay genes coding for one trait
(ex. Our height)
