[GEN BIO]: L3 Monohybrid and Dihybrid

Trait

is an observable characteristic that is inherited (passed down) from a living thing to its offspring.

(Ex. Eye color, hair color, tongue curling, blood type)

Mendelian Laws / Mendel's laws of inheritance

include law of dominance, law of segregation and law of independent assortment

• law of dominance

• law of segregation

• law of independent assortment

Mendel's laws of inheritance include: (3)

Law of Dominance

When parents with pure, contrasting traits are crossed together, only one form of trait appears in the next generation

Law of Segregation

states that alleles segregate randomly into gametes.

Law of Independent Assortment

states that the alleles of two (or more) different genes get sorted into gametes independently of one another

monohybrid cross

is a mating process between individuals with dominant genotypes, homozygous genotypes, or alleles with hereditary characteristics.

parental generation

consists of the true-breeding initial parents.

(Ex Tall x Dwarf, TT x tt)

first filial generation

consists of the offspring of the P generation.

(Ex. All Tall, TT, tt)

second filial generation

consists of the offspring of F1 gen.

(Ex. Tall Tall Dwarf Tall, )

Principle of Dominance

In a heterozygous individual, one allele (dominant) completely masks the expression of the other allele (recessive).

Laws of Segregation

The two alleles of a gene in an individual segregate or separate from each other during gamete formation

dihybrid cross

is a mating between two individuals involving two characteristics or two pairs of contrasting traits.

Law of Independent Assortment

The alleles from different genes are sorted into the gametes independently of each other. Thus, the inheritance of these two genes become independent.

Transmission genetics

is the one that is particularly concerned about themmechanisms or patterns of inheritance

law of segregation

Mendel’s monohybrid cross reveals the _____. According to this law, the alleles segregate during gametogenesis. This explains the characteristic 3:1 phenotypic ratio of F2 in monohybrid crosses

the law of independent assortment

Mendel’s dihybrid cross reveals _______. According to this law, allele pairs from different genes separate independently during gamete formation. This explains the characteristics ratio of 9:3:3:1 of F2 of dihybrid crosses

principle of the dominance

In terms of expression, genes can either be dominant or recessive. According to the ________ of Mendel, in a heterozygous individual, the dominant allele tends to mask the expression of the recessive allele.