They first 'cut out' genes using precise biological 'scissors' – restriction enzymes – and paste them into DNA from another organism like a bacterium or yeast where it is copied many thousands or millions of times. Molecular model of a restriction enzyme bound to DNA.
I believe that the principles of inheritance were formulated based on observations on the outcomes of breeding experiments. The underlying processes were unknown at the time. Mendel's observations and conclusions are summarized in the following two principles or laws. The law of segregation which states that for any trait, each parent's pairing of genes (alleles) split and one gene passes passes from each parent to an offspring. The other is the law of independent assortment which states that different pairs of alleles are passed onto the offspring independently of each other.