Genetics

Study of heredity and the variation of inherited characteristics Heredity- the biological process where parents pass on certain genes to their offspring

History Gregor Mendel Known as the “father of modern genetics” As an Austrian monk and botanist, he was able to come up with the basic principles about heredity Majority of his research was done on pea plants

Without Mendel, Charles Darwin’s idea of Natural Selection could not be explained 1. All organisms produce more offspring than can survive. 2. Some organisms in a species survive and reproduce better than others. 3. Organisms in a species show wide variation. 4. Variations are inherited and passed on to the next generation.

The Principles of Genetics Variation is random and created by: 1)Mutations 2)Crossing over in meiosis 3)Independent Assortment* 4)Random mating

What Makes a Trait? Traits are genetically determined characteristics; a gene Alleles will make up the alternative forms of that gene. Ex. Hair Color- trait/gene Blonde, Black, Brown, Red- alleles

Trait/genes: Alleles List 5 different traits or genes and 3 Alleles for each 1._______________:_______________ 2._______________:_______________ 3._______________:_______________ 4._______________:_______________ 5._______________:_______________

Characteristics of Traits Genotype The genetic make up Usually represented by a letter or letters Ex. A or Aa Phenotype The observable trait/gene The physical characteristic Ex. Brown hair, Green eyes

Characteristics of Traits Dominant The trait or allele that will mask(or dominate) over the other. Shows up more often Represented by a capital letter Ex. A Recessive The trait or allele that is being masked(or covered). Shows up less often Represented by a lower case letter Ex. a

Characteristics of Traits Homozygous Both genotype alleles are the same Ex. AA or aa, BB or bb Heterozygous Both genotype alleles are different Ex. Aa or Bb

practice What would be an example of : Homozygous Dominant (use the letter “H”)? _ HH___ Heterozygous Dominant? ___Hh__ ___ Homozygous Recessive? __hh______

Practice Round eyes are dominant to oval eyes. List the genotypes -Round __RR_____ -Round __Rr_____ -Oval __rr_______

Practice Small ears are dominant to big ears. List the phenotypes. -AA ___Small Ears_____ -Aa ___Small Ears_____ -aa ___Big Ears_______

Mendel’s 3 Laws

1 st Law – Law of Dominance One allele from the pair will be expressed while the other is unexpressed. -The allele that is expressed is considered dominant. The unexpressed allele is recessive. -Example: Black hair is dominant to Blonde hair

2 nd Law – Law of Segregation States that during meiosis two alleles will separate from each trait. Recall Meiosis – you create gametes. Law of Segregation ensures that each gamete will have one allele from the allele pair.

3 rd Law-Law of Independent Assortment States that alleles distribute randomly or independently during meiosis.  F-O-I-L  YyRr – gametes ____YR______Gamete 1   _______Yr______Gamete 2  _______yR______Gamete 3   _______yr______Gamete 4

F-O-I-L F- First O- Outer I-Inner L-Last F-AB O-Ab I-aB L-ab AaBb “INSIDE-OUTSIDE”

PRACTICE AABb aaBb Aabb How many different allele combinations were created?

Punnett Squares A punnett square is a visual aid that is used to view traits. Gives you a probability for possible outcomes when traits are crossed

Monohybrids are used to view the outcomes in offspring examining only one trait

Genotype and Phenotype Ratio Genotype Ratio: #Homozygous Dominant(BB) : #Heterozygous(Bb) : #Homozygous Recessive(bb) Ex. 0:2:2 Phenotype Ratio: #Dominant Trait : #Recessive Trait Ex. 2:2

Dihybrids Looks at the possibilities of two Different traits. Peas Two Traits: Shape (Round or Wrinkled) Color (Yellow or Green) -RrYy x RrYy FOIL- R rYy

RrYy x RrYy