A quick look back at Protein Synthesis:

Genes and Heredity

• “You’re a chip off the old block!”• The apple didn’t fall far from the

tree.”• What observations led to

speculation that characteristics are inherited?

Traits are controlled by genes on chromosomes. Your traits are the result of the interactions of the genes of both parents.

Hybrids: offspring that differ from the parent in one or more traits.

Mendels Experiments.isf

Mendel’s Experiments

• CharacteristicsCharacteristics Dominant trait Recessive Trait

Seed shape Round wrinkledSeed colour Yellow GreenPod shape Inflated constrictedPod colour Green yellowFlower colour Purple white

Dominant and recessive

• Dominant trait: genes that determine the expression of the genetic trait in the offspring

• Recessive trait: genes that are overruled by dominant genes

Mendel’s Laws of Heredity• The passing of traits from parents to offspring is

called heredity.• traits are the result of interactions of the genes of

both parents.• 1. Inherited characteristics are controlled by

factors called genes• 2. One gene masks the effects of another.

Principle of dominance• 3. A pair of factors or genes, segregate during the

formation of gametes – law of Segregation.

How Mendel showed traits being passed on.

• Dominant trait -- capital letter R• Recessive trait- lower case r• Traits occur in pairs:• RR, Rr, rr• Gene for seed shape: allele-R = round allele -r = wrinkled

Dominant vs Recessive HumansAutosomal traits