click below
click below
Normal Size Small Size show me how
Genetics Chapter 5
Interactions between genes
Question | Answer |
---|---|
INDEPENDENT GENES Phenotypes and Example | 9:3:3:1 Spotted Horse and Pepper color |
EPISTASIS (definition) | One gene masks or modifies the expression of the second gene |
RECESSIVE EPISTASIS Phenotype and Example | 9:3:4 Labrador Retrievers |
DUPLICATE RECESSIVE EPISTASIS Phenotype and Example | 9:7 Physa Snail color |
DOMINANT EPISTASIS Phenotype and Example | 12:3:1 Squash color |
DOMINANT DUPLICATE EPISTASIS Phenotype and Example | 15:1 Dominant chicken color |
MODIFIER GENES Definition and Example | Genes that interact with and affect the expression of another gene (Modify but do NOT mask) Cat color and Horse red pigmenting |
SUPERIMPOSED MINOR GENES Example | Spotting alleles prevent pigments from reaching some hairs S allele on cats, dogs and horses (more on cats and dogs, less on horses) |
ENVIRONMENTAL INFLUENCES Types of traits and Examples | Sex-influenced and sex-limited traits (male pattern baldness) Temperature-sensitive traits (Himalayan rabbits and cats) |
PLEIOTROPY Definition and Examples | A single gene affects multiple traits White eye mutation in Drosophila affects kidney function Lethal white foal disease in horses causes white coat and defective digestive system |
POLYGENIC TRAIT Definition and Examples | A single trait is affected by multiple genes Eye color in drosophila controlled by 100 different genes Human height |
CYTOPLASMIC INHERITANCE Definition and Example | Phenotype of offspring determined by genes inherited only from the mother (inherit mitochondria from mother) Leaf color of four o'clock plants |
MATERNAL EFFECTS Definition and Example | Phenotype of offspring determined by products (mRNAs) from mother's genes Shell coiling in Limnaea |
GENOMIC IMPRINTING Definition and Types | Genes whose expression is affected by the sex of the transmitting parent paternally imprinted=maternally expressed maternally imprinted=paternally expressed |
GENOMIC IMPRINTING How? | Results from methylation differences that arise during gametogenesis Heavy methylation inactivates either maternal or paternal allele (epigenic modification) |
INCOMPLETE DOMINANCE Definintion and Example | All three genotypes have different phenotypes Chicken color, eggplant color, flower color |
CO-DOMINANCE Definition and Example | Traits associated with BOTH alleles seen in heterozygote (NOT actually dominance) MN and ABO blood proteins |
Number of possible genotypes (Due to multiple alleles) | genotypes=n(n+1)/2 n=number of different alleles at a given locus |
ALLELE SERIES Definition and Example | Alles taht produce alternative phenotypes can have serial dominance relatinships C color in rabbits, mice, cats (full-color>part-colored>heat-sensitive>albino) |
RECESSIVE LETHAL Definition and Examples | Offspring homozygous for lethal allele die 1:2 phenotype, no recessive homozygote Yellow color in mice and Tail-less cats |
EARLY LETHAL | One class of offspring in crosses is missing |
POSTNATAL LETHAL Definition and Example | Incomplete skew in birth ratio Spotting (Ov gene) in horses Ratio NOT 1:2:1 or 1:2 |
DOMINANT LETHAL Definition and Example | NO embryonic dominant lethals known because all carriers would die and allele would be lost only detectable if death after reproductive age Huntington's disease in humans |
EXPRESSIVITY Definition and Example | Extent to which genotype is expressed in an individual (how much phenotype you see) Horse or dog spots (how big) |
PENETRANCE Definition and Example | Percent of individuals with genotype who show phenotype at all (whether or not you see the phenotype) Polydactyly |