Exceptions to Mendel's Rules of Genetics Mrs. Herman 2017
Mendel Genetics with a dominate and recessive trait the dominate completely masks the appearance of any other trait and there is no mixing or blending.
When the offspring s phenotype is a blend of the parent s phenotypes.
Notice that the same letters are used to represent the alleles; however, there are 3 phenotypes instead of just 2 RR = Red rr = White Rr = pink
Incomplete dominance practice problem In goblins, the number of horns shows incomplete dominance. Complete a cross between a goblin with two horns and a goblin with no horns. HH = no horns Hh = one horn hh = two horns?
Incomplete dominance practice problem In goblins, the number of horns shows incomplete dominance. Complete a cross between a goblin with two horns and a goblin with no horns. HH = no horns Hh = one horn hh = two horns h h H Hh Hh H Hh Hh Offspring would have Hh = one horn
When both alleles can be are completely expressed at the same time. This can be observed in the offspring as spots, stripes, speckles, etc. BB = black WW = white BW = checkered
Notice that in Codominance, two different letters will be used in the Punnett Square.
Codominance Practice Problem In horses, coat color is a codominant trait. What would the offspring look like if a roan horse was crossed with a red horse? Red = RR White = WW Roan = RW or WR
Codominance Practice Problem In horses, coat color is a codominant trait. What would the offspring look like if a roan horse was crossed with a red horse? Red = RR White = WW Roan = RW or WR R R RR W RW R RR RW 50% of the offspring would be Red, 50% of the offspring would be Roan
Sex-linked Traits Sex chromosomes determine if an offspring is male or female. Females have X X Male have X Y Some traits and diseases are sex-linked such as color-blindness, baldness and hemophilia.
Sex-linked Traits Afflicted = a person (organism) that has the disease or trait Carrier = a person (organism) that carries the allele, but it is not expressed (shown) Normal = a person (organisms) that does not have the allele at all and does not show the trait or disease
Sex-linked Traits The allele is written with both the gender and a superscript of the disease/trait.
Sex-linked Traits Practice Problem Eye color in fruit flies is a sex-linked trait. Cross a red eyed male with a white eyed female. Determine the phenotypes and genotypes of the offspring.
Sex-linked Traits Practice Problem Eye color in fruit flies is a sexlinked trait. Cross a red eyed male with a white eyed female. Determine the phenotypes and genotypes of the offspring.
Deals with genes with more than 2 variations. Example: Human blood has 3 alleles (A,B,O)
Blood type can be written as follows: Blood Type (phenotype) Genotype Genotype (alternative) A AA or AO I A I A or I A i B BB or BO I B I B or I B i AB AB I A I B O OO ii
Answer Parents #1 = Child z Parents #2 = Child x Parents #3 = Child y
Polygenetic Alleles Traits that are produced by many sets of genes interacting with each other. Examples: eye color, height, skin color
Beyond Mendelian Inheritance Genetics of Magical Ability
If the dragons in Harry Potter have fire power alleles F (strong fire) and F (no fire) that follow incomplete dominance, what are the phenotypes for the following dragon fire genotypes? Genotype = FF Genotype = FF Genotype = F F
If the dragons in Harry Potter have fire power alleles F (strong fire) and F (no fire) that follow incomplete dominance, what are the phenotypes for the following dragon fire genotypes? Genotype = FF Phenotype = strong fire Genotype = FF Phenotype = moderate fire (blended trait) Genotype = F F Phenotype = no fire
If merpeople have tail color alleles B (blue) and G (green) that follow the codominance inheritance rule, what are possible genotypes and phenotypes? Genotypes: BB GG BG Phenotypes: blue tail (BB) green tail (GG) blue & green tail (BG)
Multiple alleles have more than 2 variations. Ex., human blood type has 3 different allele variants, A, B, and O. Genotypes Phenotypes AA,AO A blood type AB AB blood type BB, BO B blood type OO O blood type
If parents have A (AO) and B (BB) blood types, what are the possible genotypes and phenotypes of their children?
If parents have A (AO) and B (BB) blood types, what are possible genotypes and phenotypes of their children? Genotypes: AB and BO Phenotypes: AB and B blood types
What is the genotype for Harry s eye color? If he had any siblings, what colors would their eyes be? Eye color in humans has multiple alleles: B = brown (codominant with green) G = green (codominant with brown) b = blue (recessive to both brown and green) Draw a Punnett Square with Harry s parents: assuming Lily with green eyes (GG) and James with hazel eyes (BG).
There is a 50% chance that Lily and James would have a child with green hazel eyes. Harry inherited the green eyes