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Genetics Practice. Do Now: match the following words with their definitions. Sponge Bob Genetics. Review & Questions. Genetics Self-Test. You have 15 minutes to complete 10 genetics questions which range in difficulty from easy to very hard.
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Genetics Practice Do Now: match the following words with their definitions
Sponge Bob Genetics • Review & Questions
Genetics Self-Test • You 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 we’ve been working on for the last week
Self-test Results • Bear hair • Since straight hair is dominant: • SS straight hair • Ss straight hair (heterozygous) • Ss curly hair
Bear-hair cross • Heterozygous bear on top, curly haired bear on side. • Genotype ratio: 1:1 Ss:ss • Phenotype ratio: 1:1 straight:curly
Heterozygous Bear Cross • Genotype ratio: 1:2:1 SS:Ss:ss • Phenotype ratio 3:1 straight:curly
Fruit Flies • Since 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)
Two red-eyed flies with white-eyed offspring • Since 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)
Codominance • Since there are 3 phenotypes (red, white, and roan), you immediately know this is codominance or incomplete dominance • Since the third phenotype is a result of BOTH alleles being expressed, it must be codiminance. • Red x Roan = 50% will be roan
Roan x Roan • 1:2:1 Red:Roan:White
Morning Glories • Since the third phenotype in this example is a blending of the two phenotypes, it is an example of incomplete dominance • VV = violet • VV’ = light purple • V’V’ = white • 1:2:1 violet:light purple: white
Sex-linked heredity • When a gene is located on the sex chromosomes, it is said to be a sex-linked trait • X+X+ normal f • X+Xo carrier f • XoXo color-blind f • X+Y normal m • XoY color-blind m • 50% of males will be color blind • 50% of females will be carriers
Rate Yourself • Only count a question as right if you got ALL parts right • < 6 right = deep trouble • 6-7 right = not too good • 8 right = on track • 9 right = nice • 10 right = AWESOME!