Genetics

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

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 History

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. Without Mendel, Charles Darwin’s idea of Natural Selection could not be explained

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

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 What Makes a Trait?

List 5 different traits or genes and 3 Alleles for each _______________:_______________ Trait/genes: Alleles

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

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

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

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

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

Practice Small ears are dominant to big ears. List the phenotypes. -AA

Mendel’s 3 Laws

Mendel’s 1st Law 1st 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 Mendel’s 1st Law 15

Mendel 2nd Law 2nd 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. Mendel 2nd Law 16

Mendel’s 3rd Law 3rd 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 Mendel’s 3rd Law 17

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

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

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

Monohybrid Punnett Squares Monohybrids are used to view the outcomes in offspring examining only one trait Monohybrid Punnett Squares 21

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 Genotype and Phenotype Ratio

Dihybrids Peas Looks at the possibilities of two different traits. Two Traits: Shape (Round or Wrinkled) Color (Yellow or Green) -RrYy x RrYy FOIL- R r Y y Dihybrids Looks at the possibilities of two different traits. 23

RrYy x RrYy