Gene interactions Flashcards
What are gene interactions?
Interactions between allelic and non-allelic genes of the same genotype in the production of phenotypic characteristics
What is the wild type gene?
the gene that encodes for the phenotype most common in particular natural population
what is the mutant gene?
any form of that allele other than the wild type
What is Haplosufficiency?
When an individual who is homozygous or heterozygous dominant and sufficient to produce wild-type phenotypes
What is haploinsufficiency?
When an individual who is heterozygous or hemizygous is incapable of producing the wild-type phenotype
Which is the functional allele?
The dominant
What does it mean if an organism is haploinsufficient?
when a single copy of the standard (so-called wild-type) allele at a locus in heterozygous form is insufficient to produce the standard phenotype
Name the 5 types of gene interactions
- Dominant/recessive
- Co-dominant
- Incomplete dominance
- Sex-linked
- Multiple alleles
What is the type of interaction called between alleles at different loci?
epistasis
What is epistasis?
Interactions between alleles at different loci
“the masking of the phenotypic effects of alleles at one gene loci by alleles of another gene loci “
What is co-dominance?
When neither allele is recessive so both alleles are expressed in the phenotype equally
i.e: blood groups A and B in humans to create ABO
What are lethal genes?
Genes that can cause the death of the organisms that carry them.
Sometimes, death is not immediate; it may even take years, depending on the gene
Give an example of lethal genes
Cystic fibrosis Sickle-cell anemia Huntington's disease Yellow mice Tail-lessness in manx cats
What are sub-lethal genes
when genes have the potential to be lethal in certain situations - not all individuals with the genes will die as a consequence
i.e: Haemophilia
What are dominant and recessive lethal genes?
Dominant - when just one dominant copy of the gene is fatal
Recessive - when two copies are needed to be fatal
what are sex-linked genes
traits are genetic characteristics determined by genes located on sex chromosomes
Give an example of a sex-linked gene
Haemophilia A in thorougbred horses is transmitted by X chromosome
The gene for tabby cats are only found in female cats
What are multiple alleles?
When there are three or more possible alleles for one individual trait
i.e: coat colour
what is polygenetic inheritance?
occurs when one characteristic is controlled by two or more genes – often genes are large in quantity but with small effect
what is incomplete dominance?
where a heterozygote phenotype intermediates between two homozygote phenotypes - neither allele is completely expressed so the phenotype is a mixture of the two
example: black and white chickens = a blue chicken
What is pleiotrophy?
when one gene influences two or more seemingly unrelated phenotypic traits
give an example of pleiotrophy?
40% of white furred cats with blue eyes are also deaf (Hartl & Jones, 2005)
what is the masking of the phenotypic effects of alleles at one gene loci by alleles of another gene loci known as?
Epistasis
What is the epistatic allele?
The allele that does the masking
what is the hypostatic allele?
The allele that is being masked
what is the MASKED allele known as?
the hypostatic allele
what is the allele that does the masking known as
the epistatic allele
what is dominant epistasis?
When the dominant allele of one gene masks the expression of ALL alleles of another gene
what is recessive epistasis?
when the recessive allele of one gene masks the effects of either allele of the second gene when present in homozygous form
