Origin of Genetics (Leaving Cert Biology): Revision Notes
📚 Revision Notes
Origin of Genetics
The Father of Genetics: Gregor Mendel
- Known as the father of genetics, Gregor Mendel was an Augustinian monk who conducted experiments on pea plants in the mid-1800s.
- He studied seven characteristics of pea plants and determined patterns of inheritance.
- His findings formed the foundation of modern genetics and led to the formulation of two laws of inheritance.
- Mendel's First Law – The Law of Segregation
- Mendel's Second Law – The Law of Independent Assortment
Mendel's First Law – The Law of Segregation
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Mendel's First Law - The Law of Segregation Mendel's law of segregation states that inherited characteristics are controlled by pairs of factors. These factors segregate at gamete formation so that only one factor is carried in each gamete.
- What Mendel called 'factors' are now known as alleles.
- He predicted that:
- Alleles occur in pairs (indicating cells are diploid).
- A process (now known as meiosis) resulted in the number of alleles being halved during gamete formation.
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Definition Review: Allele: A different form of the same gene.
Mendel's Second Law – The Law of Independent Assortment
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Mendel's Second Law - The Law of Independent Assortment Mendel's second law states that at gamete formation, either member of a pair of factors is equally likely to recombine with either of another pair of factors.
- This means that the inheritance of one trait is independent of the inheritance of another trait.
- Example:
- If a cell has the genotype TtPp, the possible gametes are: TP, Tp, tP, and tp.
- Each gamete type is equally likely to form.