Lesson Outline Gregor Mendel Genetic Laws and Principles

Gregor Mendel �an Austrian monk who used garden pea plants to explain the inheritance

Gregor Mendel �Mendel examined seven different pea traits �each trait had only two possible

Gregor Mendel �Mendel was the first individual to propose the principal of dominance, the

Genetic Laws and Principles Principle of Dominance �when individuals with different alleles reproduce, the

Genetic Laws and Principles Law of Segregation �chromosome pairs split up during meiosis with

Genetic Laws and Principles Law of Independent Assortment �the inheritance of traits are independent

Lesson Outline √ �Gregor Mendel �Genetic Laws and √ Principles �Crosses �Generation Terms �Punnett

Crosses �we will be looking at three different types of crosses… Monohybrid Cross n

Crosses �we will be looking at three different types of crosses… Dihybrid Cross n

Crosses �we will be looking at three different types of crosses… Test Cross n

Lesson Outline √ �Gregor Mendel �Genetic Laws and √ Principles �Crosses √ �Generation Terms

Generation Terms �P 1 = parent generation �F 1 = first filial generation (children)

Punnett Squares �a punnett square is a chart used by geneticists to determine the

Punnett Squares �in monohybrid crosses, a 2 x 2 punnett square is used

Punnett Squares �the possible gametes produced by the parents are written at the top

Punnett Squares �the gametes are combined to produce all of the possible F 1

� Find the genotypes and phenotypes of the F 1 and F 2 generations

T T t Tt Tt F 1 genotypes = all Tt F 1 phenotypes

� to find the F 2 generation, you cross the offspring produced in the

Punnett Squares �in the case of a cross that involves parents that are homozygous

Punnett Squares F 1 will always have: • Genotypes that are heterozygous • Phenotypes

Punnett Squares F 2 will always have a: • Genotypic ratio of 1: 2:

Test Cross unknown parent BB? or Bb? x known parent bb (homozygous recessive)

Test Cross �Case #1 – unknown parent = BB B B b Bb Bb

Test Cross �Case #2 – unknown parent = Bb B b b Bb bb

Slides: 38

Download presentation

Lesson Outline �Gregor Mendel �Genetic Laws and Principles �Crosses �Generation Terms �Punnett Squares

Gregor Mendel �an Austrian monk who used garden pea plants to explain the inheritance of characteristics Gregor Mendel (1822 -1884)

Gregor Mendel �Mendel examined seven different pea traits �each trait had only two possible variations (alleles) Gregor Mendel (1822 -1884)

Gregor Mendel �Mendel was the first individual to propose the principal of dominance, the law of segregation, and the law of independent assortment

Lesson Outline √ �Gregor Mendel �Genetic Laws and Principles �Crosses �Generation Terms �Punnett Squares

Genetic Laws and Principles Principle of Dominance �when individuals with different alleles reproduce, the offspring will only express the dominant trait

Genetic Laws and Principles Law of Segregation �chromosome pairs split up during meiosis with one member of each pair going into separate gametes

Genetic Laws and Principles Law of Independent Assortment �the inheritance of traits are independent of each another

Lesson Outline √ �Gregor Mendel �Genetic Laws and √ Principles �Crosses �Generation Terms �Punnett Squares

Crosses �we will be looking at three different types of crosses… Monohybrid Cross n involves one trait a

Crosses �we will be looking at three different types of crosses… Dihybrid Cross n involves two traits

Crosses �we will be looking at three different types of crosses… Test Cross n involves the cross of an individual with a homozygous recessive individual (bb) in order to determine the phenotype of the first individual

Lesson Outline √ �Gregor Mendel �Genetic Laws and √ Principles �Crosses √ �Generation Terms �Punnett Squares

Generation Terms �P 1 = parent generation �F 1 = first filial generation (children) �F 2 = second filial generation (grandchildren)

Lesson Outline √ �Gregor Mendel �Genetic Laws and √ Principles �Crosses √ �Generation Terms √ �Punnett Squares

Punnett Squares �a punnett square is a chart used by geneticists to determine the probability of results when two individuals are crossed

Punnett Squares �in monohybrid crosses, a 2 x 2 punnett square is used

Punnett Squares �the possible gametes produced by the parents are written at the top and along the side B Mother = Bb b

Punnett Squares �the possible gametes produced by the parents are written at the top and along the side B Mother = Bb Father = bb b

Punnett Squares �the gametes are combined to produce all of the possible F 1 genotypes B Mother = Bb Father = bb b b Bb Bb b bb bb

� Find the genotypes and phenotypes of the F 1 and F 2 generations when a homozygous tall (T) pea plant is crossed with a homozygous short (t) plant Given: Parent A = TT Gametes: T T Parent B = tt t t

T T t Tt Tt F 1 genotypes = all Tt F 1 phenotypes = all tall

� to find the F 2 generation, you cross the offspring produced in the F 1 generation Given: Parent A = Tt Gametes: T t Parent B = Tt T t

T t T TT Tt tt F 2 genotypes = 1 TT : 2 Tt : 1 tt (1: 2: 1 ratio) F 2 phenotypes = 3 tall : 1 short (3: 1 ratio)

Punnett Squares �in the case of a cross that involves parents that are homozygous for a particular trait:

Punnett Squares F 1 will always have: • Genotypes that are heterozygous • Phenotypes that resemble the dominant trait

T T t Tt Tt F 1 genotypes = all Tt F 1 phenotypes = all tall

Punnett Squares F 2 will always have a: • Genotypic ratio of 1: 2: 1 1 homozygous dominant 2 heterozygous 1 homozygous recessive • Phenotypic ratio of 3: 1 3 dominant 1 recessive

T t T TT Tt tt F 2 genotypes = 1 TT : 2 Tt : 1 tt (1: 2: 1 ratio) F 2 phenotypes = 3 tall : 1 short (3: 1 ratio)

Test Cross unknown parent BB? or Bb? x known parent bb (homozygous recessive)

Test Cross �Case #1 – unknown parent = BB B B b Bb Bb • if all F 1 show the dominant trait, then the unknown parent was BB

Test Cross �Case #2 – unknown parent = Bb B b b Bb bb • if even one F 1 shows the recessive trait, then the unknown parent was Bb

Lesson Outline √ �Gregor Mendel �Genetic Laws and √ Principles �Crosses √ �Generation Terms √ �Punnett Squares √