[LESSON 1]

Gregor Johannes Mendel

He is an AUSTRALIAN MONK, WHO CARRIED OUT AN EXPERIMENT ON GARDEN PEAS TO EXPAND HIS KNOWLEDGE ON THE TRANSMISSION OF GENES from parents to offspring.

Genetics

It is a BRANCH OF BIOLOGY WHICH DEALS WITH HEREDITY AND VARIATION.

Traits

It is the OBSERVABLE CHARACTERISTICS IN AN ORGANISM.

Phenotype

It is the PHYSICAL EXPRESSION OF THE TRAITS.

Monohybrid cross

It is a CROSS WHICH INVOLVES ONLY ONE PAIR OF CONTRASTING TRAITS.

Dihybrid cross

This is a CROSS WHICH INVOLVES TWO PAIRS OF CONTRASTING TRAITS.

P1

This CONSTITUTES FOR THE PARENTS.

F1

It CONSTITUTES FOR THE FIRST FILIAL GENERATION WHICH IS THE OFFSPRING OF THE PARENTAL GENERATION.

Principle of Paired Unit Factors

PRINCIPLE AND LAWS OF INHERITANCE

It is where TRAITS ARE CONTROLLED BY UNIT FACTORS WHICH EXIST IN PAIRS IN INDIVIDUAL ORGANISMS.

Genes

PRINCIPLE AND LAWS OF INHERITANCE

It is the UNIT FACTORS THAT CONTROL THE TRAITS.

Principle of Paired Unit Factors

PRINCIPLE AND LAWS OF INHERITANCE

For any character, the PHENOTYPE IS DETERMINED BY ALTERNATIVE FORMS OF A SINGLE GENE, CALLED ALLELES.

Alleles

It is a FORM OF A SINGLE GENE.

Principle of Paired Unit Factors

PRINCIPLE AND LAWS OF INHERITANCE

EX: EACH INDIVIDUAL RECEIVES ONE FROM EACH PARENT.

• In the case of the trait for stem height, three combinations of the factors are possible: two factors for tall stems, two factors for dwarf stems, or one of each factor.

Law of Dominance

PRINCIPLE AND LAWS OF INHERITANCE

This law states that IF AN INDIVIDUAL INHERITS DIFFERENT ALLELES FOR THE SAME TRAIT, ONE ALLELE MAY BE DOMINANT TO THE OTHER.

Law of Dominance

PRINCIPLE AND LAWS OF INHERITANCE

• The expression of the trait is DETERMINED BY THE DOMINANT ALLELE, WHICH IS WRITTEN IN CAPITAL LETTER.

• The trait NOT EXPRESSED IS CALLED THE RECESSIVE ALLELE, which is WRITTEN IN SMALL LETTER.

• EX: dominant and recessive allele (e.g. tall-T, dwarf-t)

Law of Segregation

PRINCIPLE AND LAWS OF INHERITANCE

This law states that DURING THE FORMATION OF THE GAMETES, AN INDIVIDUAL RECEIVES ONE ALLELE FROM EACH PARENT.

Genotype

PRINCIPLE AND LAWS OF INHERITANCE

It is the GENETIC MAKEUP OF AN ORGANISM FOR A SPECIFIC TRAIT.

• When ALLELES ARE WRITTEN IN PAIRS, IT IS THE RESULTING SYMBOL.

Homozygous

PRINCIPLE AND LAWS OF INHERITANCE

When BOTH ALLELES ARE THE SAME (TT or tt)

Heterozygous

PRINCIPLE AND LAWS OF INHERITANCE

When the TRAIT OF THE ALLELES ARE DIFFERENT.

Law of Independent Assortment

PRINCIPLE AND LAWS OF INHERITANCE

This law STATES THAT THE SEGREGATION OF A PAIR OF ALLELES IS INDEPENDENT OF THE SEGREGATION OF THE OTHER PAIRS DURING GAMETE FORMATION.

• Whichever ALLELE IS RECEIVED BY THE OFFSPRING, IT WILL NOT INFLUENCE THE SEGREGATION OF THE OTHER.

Punnett Squares

It is a DIAGRAM IN PREDICTING THE POSSIBLE OFFSPRING OF A CROSS BETWEEN TWO PARENTS.

Punnett Squares

It is NAMED AFTER REGINALD C. PUNNETT, WHO DEVISED THIS APPROACH.