Genetics Practice

Do Now: match the following words with their definitionsGenetics PracticeSponge Bob GeneticsReview & QuestionsGenetics Self-TestYou have 15 minutes to complete 10 genetics questions which range in difficulty from easy to very hard.The self-test will not be graded, but it will let you know how well you understand the material weve been working on for the last weekSelf-test ResultsBear hair

Since straight hair is dominant:

SS straight hairSs straight hair (heterozygous)Ss curly hairBear-hair crossHeterozygous bear on top, curly haired bear on side.

Genotype ratio: 1:1 Ss:ss

Phenotype ratio: 1:1 straight:curlySssSssssSsssHeterozygous Bear CrossGenotype ratio: 1:2:1 SS:Ss:ssPhenotype ratio 3:1 straight:curlySsSSSSssSsssFruit FliesSince white eyes are recessive to red eyes, the white-eyed fly must have the rr genotype.

Since the cross produced some white eyed offspring, the red-eyed parent must be a heterozygote.

Since the phenotype ratio is 1:1, you should expect an equal number of red-eyed and white-eyed offspring (60)RrrRrrrrRrrrTwo red-eyed flies with white-eyed offspringSince this cross produced white-eyed offspring, both parents must have had a copy of the recessive allele. In other words, they are both heterozygous.

Since the phenotype ratio of the cross is 3:1 red:white, we expect there will only be 1/3 as many white eyed flies as red. (10)RrRRRRrrRrrrCodominanceSince there are 3 phenotypes (red, white, and roan), you immediately know this is codominance or incomplete dominanceSince the third phenotype is a result of BOTH alleles being expressed, it must be codiminance.

Red x Roan = 50% will be roanRRRRRRRrRrRrRoan x Roan1:2:1 Red:Roan:WhiteRrRRRRrrRrrrMorning GloriesSince the third phenotype in this example is a blending of the two phenotypes, it is an example of incomplete dominanceVV = violetVV = light purpleVV = white

1:2:1 violet:light purple: whiteVVVVVVVVVVVVSex-linked heredityWhen a gene is located on the sex chromosomes, it is said to be a sex-linked trait

X+X+ normal fX+Xo carrier fXoXo color-blind fX+Y normal mXoY color-blind m

50% of males will be color blind50% of females will be carriersX+XoX+X+X+X+XoYX+YXoYRate YourselfOnly count a question as right if you got ALL parts right

< 6 right = deep trouble6-7 right = not too good8 right = on track9 right = nice10 right = AWESOME!