Early Theories Pangenesis egg and sperm consist of particles which develop into parts of the body where they were derived Aristole Homunculus miniature person in sperm Leeuwenhoek ID: 301918
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Slide1
Classical GeneticsSlide2
Early Theories
Pangenesis
– egg and sperm consist of particles, which develop into parts of the body where they were derived – AristoleHomunculus – miniature person in sperm - Leeuwenhoek - Egg contains the entire persons – de GraafBlending of parental traits – lead to our current view of inheritance.Slide3
Mendel – The Father of Genetics
Was a monk – only way he could further his
education
He bred, tended, and analyzed over 28000 pea plants.Started with true breeding plants.Slide4
Mendel’s Laws
Law of Segregation
– all individuals have two copies of each factor (gene). These copies separate randomly during gamete formation and each gamete only gets one copy.
Law of Independent Assortment – two alleles for one genes segregate independently of the alleles for other genes during gamete formation.Slide5
Key Terms
Monohybrid cross
– looking at only
SINGLE characteristicDihybrid cross – looking at TWO characteristicsAlleles –same gene but different instructionSlide6
More Terms - YIPEE
Dominant
– genes which determine the expression of the trait
Recessive – genes which are overruled by dominant genesComplete Dominance – one gene shows over the otherSlide7
More Terms – Having fun yet?!
Genotype
– combination of alleles of any given trait
Phenotype – physical form you can observe.Slide8
Guess What? – MORE TERMS!!!
Homozygous
– two identical alleles.
Heterozygous – two different alleles for each traitSlide9
Almost Done with Terms -
Punnett Square
Test Cross
– a cross between an organism of unknown genotype and a homozygous recessiveSlide10
Generations - Labelling
Parental
–
P generation First filial – F1 – the offspring from parental generationSecond filial – F2 – the offspring from the F1Slide11
In cats, long hair is recessive to short hair. A true-breeding (homozygous) short-haired male is mated to a long-haired female. What will their kittens look like?Slide12
Two cats are mated. One of the parent cats is long-haired (recessive allele). The litter which results contains two short-haired and three long-haired kittens. What does the second parent look like, and what is its genotype?Slide13
Mrs. And Mr. Smith both have widow’s peaks (dominant). Their first child also has a widow’s peak, but their second child doesn’t. Mr. Smith accuses Mrs. Smith of being unfaithful to him. Is he necessarily justified? Why or why not? Work the genetics problem predicting the frequencies of the versions of this trait among their prospective children.