Midterm Flashcards
Dominance (allelic) serries
Complex relationship. Contains incomplete dominance and codominance
Wild type alleles
Most common, usually shown with a + superscript
Functional enzyme or protein is produced
Usually dominant over the loss of function allele (enzyme/ protein is either non- functional, not produced or produced less)
haploinsufficiency
When half of the protein is synthesized, but this is enough for the wild type phenotype
The gain of function mutations
This is an exception to the rule, dominant alleles. A detrimental function
haploinsufficiency
In a heterozygote, when half as much protein is synthesized and it is not enough
Lethal alleles
Affect on the tail is dominant, the lethal effect is recessive
environmental factors that affect penetrance and expressivity
Age, sex, chemicals, temperature (some pigments of cat hair is only in lower extremities where it is cooler)
Norm of reaction
How the genotype is affected by the reaction
genetic interaction
Combination of alleles from two or more genes can result in different phenotypes because of interactions between their products at the cellular or biochemical levels
Complementation
genes at different loci produce a single phenotype (this is the difference between dominance, where alleles are at the same loci)
The other gene supplies the wild type allele to complement the mutated allele
9:7
Heterogenous trait
A mutation in any one of a number of genes can give rise to the same phenotype`
Epistasis
Epistatic gene masks the hypostatic gene
Recessive epistasis
9:3:4
Dominant epistasis
12:3:1
Pleiotropy
A single gene can be responsible for a number of distinct and seemingly unrelated phenotypic effects
Inbreeding (consanguineous mating)
Double bars in a pedigree
Increases the probability they will be recessive for mutant alleles, can cause genetic problems
Heterosis
when two different inbred lines are crossed, the hybrids are heterozygous for many genes
hardy Weinberg principle
random mating, no mutation, migration or natural selection. Only needed when talking about genotype frequencies, use part of it when talking about allele frequencies
Phenocopy effect
Poisoning which produces a phenotype which mimics a genetically caused phenotype
Dosage compensation
Way of equalizing gene expression in the face of different gene dosage (numerous genes seem to escape for unknown reason)
X inactivation
Proposed that Barr bodies are inactive x chromosomes if a cell contains more than two x chromosomes all but one are inactive. therefore, females are functionally hemizygous for x- linked genes at the functional level
The x chromosome that is deactivated is completely random, happens early on in development
This is an example of dosage compensation in females
Aneuploidy
The number of sets of chromosomes does not change, individual chromosomes change. For some reason, humans can tolerate aneuploidies when it comes to sex chromosomes much better than autosomes.
Nullisomy
2n-2
Monosomy
2n-1
Trisomy
2n+1
Double trisomy
2n+1+1
Tetrasomy
2n+2
Turner syndrome
(XO) Short stature (can receive growth therapy, as well as estrogen at puberty for breast development) wide chested, normal IQ, webbing of the knee is common
Ovaries fail to develop, uterus and oviducts can be small and immature
Klinefelter syndrome
(XXY) sterile
Phenotypic features differ after puberty, breast development and female body fat distribution
testosterone therapy coupled with breast tissue removal will result in a more typical male phenotype
Triple X females
Phenotypically normal, can be taller than average, some fertility problems
Jacob’s syndrome
(XYY)
Phenotypically normal, usually taller than average
