Mendel inheritance

Cross

Fertilization of a female of specific genetic origin with a male gamete of specific genetic origin

Dominant

An allele that shows its trait even when only one copy is present. Represented by a capital letter.

F1 generation

The offspring of a cross of the p generation (parent generation)

F2 generation

The offspring of a cross between the f1 generation

Genotype

The combination of alleles for any given trait, or the organism’s entire genetic makeup, Ex: YY, Yy or yy?

Heterozygous

An organism that has two different alleles of a gene. Ex: Yy

Homozygous

An organism that has two identical alleles of a gene.

Homozygous dominant: YY

Homozygous recessive: yy

Law of segregation

Each parent has two alleles for a trait, but separates them when making sex cells (gametes). each gamete receives only one.

Monohybrid cross

Cross in which only one trait is monitored in the cross.

P generation

The original parent organisms used in Mendel’s experiments. They are crossed to produce offspring.

Phenotype

The physical or physiological traits of an organism.

Recessive

An allele that is hidden by a dominant allele. It only shows when two recessive copies are present. represented by a lowercase letter.

Trait

Specific characteristics of feature exhibited by an organism.

True breeding

Organisms that exhibits the same traits, generation after generation.

Dihybrid cross

Across that studies the inheritance of two different traits at the same time.

Law of independent assortment.

Alleles for different traits are passed down independently of one another (when the genes are unlinked).

Punnett square

A chart used to predict the possible genotypes and phenotypes of offspring.

Test cross and it’s purpose

A cross between an organism with a dominant looking trait and a homozygous recessive organism. It’s purpose is to determine whether the organism with the dominant trait is homozygous or heterozygous.

Autosomal dominant

The inheritance of a dominant phenotype gene is on the autosomal chromosome.

• Occurs when the disease causing allele is dominant

Autosomal inheritance

Inheritance of traits determined by a genes on the autosomal chromosome.

Autosomal inheritance

Inheritance of traits determined by a genes on the autosomal chromosome.

Pedigree

A flow chart that uses symbols to show the inheritance patterns of a family over many generations.

Why can only women be “carriers” of x-linked traits?

Females have 2 X chromosomes, so they can have one affected allele and one normal allele. The normal allele can mask the recessive one making them carriers without showing the trait. Males have only one X chromosome so if they inherit the affected allele, they usually show the trait rather than being carriers.

Why did Mendel use pea plants?

• they grow and reproduce quickly

• They produce many offspring

• They have clear easy to observe traits like flower color

• They can self pollinate or be cross pollinated

• Easy to grow and study