10-1 Mendel’s Law of Heredity
Gregor Mendel was an Austrian monk who did experiments with pea plants to
help understand genetics/heredity (1869). He is known as the “Father of
Genetics.”
Gametes carry genetic information from each parent (sexual reproduction). Called
sperm/egg in animals. Pollen/ovule in plants.
When male and female gametes meet, fertilization occurs. At that point the
fertilized cell is called a zygote. Called pollination in plants.
Rule of Dominance - Mendel determined that some traits are dominant and some
are recessive. A recessive gene cannot be expressed in the presence of a dominant
gene.
Rule of Unit Factors – each organism that is reproduced sexually, gets a gene for
each trait from each parent (two genes for each trait).
In some cases, there are different variations of a gene (alleles). For example, there
is a gene for tall/short or yellow/green .
Law of Segregation – half of the gametes produced by an individual will carry one
allele, while the other half will carry the other.
Law of Independent Assortment – traits are inherited independently of one another.
Homozygous – having two of the same genes (alleles) for a trait.
Homozygous dominant – having two dominant alleles for a trait ,also called pure
dominant
Homozygous recessive – having two recessive alleles for a trait, also called pure
recessive.
Heterozygous – having two different genes (alleles) for a trait.
Genotype – genes that an individual has (not all genes/alleles are expressed).
Phenotype – genes that an individual shows (genes that are expresses).
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