[BIO2] Genetics

Gregor Johann Mendel

father of genetics

Pisum sativum

garden pea plant

monohybrid cross

a cross involving a single trait

alleles

one of two or more versions of a gene

Parental Generation

a cross of purebred (homozygous) parents.

F1 (First Filial Generation)

the product of the Parental Generation

F2 (Second Filial Generation)

the product of the self-fertilization of the products of F1 generation.

homozygous

the same alleles

heterozygous

different alleles

genotype

genetic make-up

phenotype

physical make-up

The Principle of Dominance and Recesiveness

“One factor in a pair may mask the expression of the other”

Dominant allele

the expressed trait

Recessive allele

masked trait that reappears in the F2 generation

Mendelian Principles

1. Principle of Dominance and Recesiveness

2. The Law of Segregation

3. The Law of Independent Assortment

The Law of Segregation

“A gene pair carries two separate characteristics”

egg and sperm cell

Carry the hereditary factors that the offspring receives one factor from each parent

dihybrid cross

a cross involving two traits.

The Law of Independent Assortment

“During gamete formation, the gene pair assorts independently”

Non-Mendelian Patterns of Inheritance

1. Incomplete Dominance

2. Codominance

3. Multiple Alleles

Incomplete Dominance

“The pattern of inheritance, where an intermediate phenotype other than the two parental phenotypes, is observed.”

Codominance

Both alleles are expressed, resulting in the formation of the phenotype or characteristics.

Multiple Alleles

blood group

Rhesus factor

is an inherited protein found on the surface of red blood cells.

Lethal Genes

certain combination of alleles will result to the death of the carrier

agglutinogens

most common means of blood typing

agglutinin

the presence agglutinogens causes this

Polygenic Inheritance

traits that are controlled by two or more genes

polygenes

genes involved in polygenic inheritance

Sex-Linked Inheritance

genes are located in the sex chromosomes

Sex-Influenced Inheritance

autosomal traits whose expression of dominance is affected by the sex of the individual

Pleiotropy

one gene casuses several effects (multiple traits) in various organs of the body

Reginald Punnett

person who developed the punnett square

genome

set of all the genes found in a cell responsible for the characteristics of an individual

homologous chromosomes

pair of paternal and maternal chromosomes