Mendel's Laws

Mendel’s “laws”
Segregation: According to Mendel’s model, when any individual produces gametes, the two copies of a gene separate, so that each gamete receives only one copy.
Traits cluster into organisms with and without traits (no intermediate categories)
Exceptions: hair color, skin color, eye color, etc
Organism is either this or that – has freckles or doesn’t. Is tall or not.

Independent assortment: alleles of different genes inherited independently of one another during gamete formation; applies to genes located on separate chromosomes, but not always to those located on the same chromosome (Chromosomes have more than one trait/gene per chromosome – so independent assortment doesn’t always hold up when traits are close together on one chromosome)
Traits inherited independently (inheriting 1 trait doesn’t predict for inheriting separate trait)
EX: just because plants were tall, it didn’t mean all of the flowers are the same color
Independent assortment caused by meiosis – mom and dad chromosomes go to either cell – ½ complement on either side of cell.
Copies of genes on different chromosomes are split independently before crossing over (in metaphase 1)
Chromosomes are divided randomly

Meiosis and Mendelian genetics
Because of crossing over of large sections of chromosomes in meiosis, genes that are close to each other on same chromosome are likely to be inherited together (genes are linked)
This disproves independent assortment
Look over figure 10.18 – will be test question similar to this

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