MENDEL and

HEREDITY

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Gregor Mendel

He is the Father of GENETIC.

He used Pea Plants (Pisum sativum) for experiment.

He crossed Pea Plants with different Traits.

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Gregor Mendel (an Austrian monk) made the first studies in predicting how traits would transfer from one generation to another.

What is GENETIC ?

Genetics is the study of HEREDITY.

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What is HEREDITY ?

The passing on of characteristics (traits) from parents to offspring.

WHY MENDEL USED PEA PLANT FOR HER EXPERIMENT ?

o They have two distinct, male and female, sex cells called gametes.

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o Pea plants are also inexpensive, easy to maintain, and grow quickly.

o Mendel used pea plants because they easily known each of its traits.

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Mendel controlled thefertilization of his pea plantsby removing the male parts,or stamens.

He then fertilized the femalepart, or pistil, with pollen froma different pea plant.

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Pea Plant can harvest for only 12 to 15 Weeks.

Characteristic of Pea Plant

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He crossed Pea Plants with different Traits

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• Fertilization - the uniting of male and female gametes (sex cell).

• Cross - combining gametes from parents with different traits.

P1 = parent in the 1st generation

The offspring of P1 were called the F1 generation

“F” stands for filialFilial stands for son or daughter

The offspring of the cross between 2 F1 plants were called the F2 generation

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What Did Mendel Find?He discovered different laws and rules

that explain factors affecting heredity

Each organism has two alleles for each trait

Alleles - different forms of the same gene.

Genes - Units responsible for passing on traits from one generation to the next.

Rule of Unit Factors

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Rule of DominanceDominant Alleles

In heterozygote, the allele that is fully expressed in the phenotype.

The letter should be (uppercase)

Recessive Alleles

In the homozygous, its expression masked in the presence of a dominant gene.

The Letter should be (lowercase)

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LAW OF SEGREGATIONThe offspring then receives its own pair of alleles for that trait. Whichever of the two alleles in the offspring is dominant determines how the offspring expresses that trait (e.g. the color and height, etch.).

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State that allele pairs separate independently during the formation of gametes. this means that traits are transmitted to offspring independently of one other.

Law of Independent Assortment

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oGenotype:the gene combination of an organism.

o-AA or Aa or aa

oPhenotype: the way an organism looks.o-red hair or brown hair

 

Genotype and Phenotype

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Homozygous and HeterozygousoHomozygous: if the two alleles for a trait are the same (TT or tt)

oHeterozygous: if the two alleles for a trait are different (Tt)

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Homozygous

Heterozygous

Dihybrid vs Monohybrid

• Dihybrid Cross - crossing parents who differ in two traits (AAEE with aaee)

• Monohybrid Cross - crossing parents who differ in only one trait (AA with aa)

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In some species of plants, tall plants are dominant to short plants. Predict the outcomes between a homozygous dominant plant and a short plant.

TT x ttT = tall dominant plant t = short plant

Genotype- 100 % TallPhenotype- Tall