Mendelian Genetics

P

parental generation

F1

first filial generation (offsprings of parents)

F2

second filial generation

what was mendel’s principles

1. alleles cause variations in inherited characteristics among off springs

2. every organism inherits one allele from each parent

3. dominant allele willy be fully expressed if two alleles are different

4. law of segregation

allele

alternate versions of a gene

law of segregation

1. each organism has two alleles for each trait

2. alleles separate during meiosis

3. gamete contains only one of the factors

dominant allele is expressed with

capital letters (ex. PP)

recessive allele is expressed with

lowercase letters (ex. pp)

homozygous

2 of the same alleles (ex. PP or pp)

heterozygous

2 of different alleles (ex. Pp)

locus

location of gene on homologous chromosomes

phenotype

expressed physical trait (ex. brown hair)

genotype

genetic make up (ex. Pp)

law of dominance

1. only one form of the trait will appear in the next generation

2. if an organism inherits at least one dominant allele, the will exhibit dominant phenotype

3. if organism inherits two recessive alleles, they will exhibit recessive phenotype

monohybrid cross

study one character (ex. color)

dihybrid cross

study 2 characters (ex. color and shape)