| 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 |
Biology Lab Midterm
