The Monk who loved peas How to Make a Living Thing.
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Transcript of The Monk who loved peas How to Make a Living Thing.
The Monk who loved peasThe Monk who loved peas
How to Make a Living Thing
Gregor MendelGregor Mendel Monk, failed teacher, pea-lover, genetic genius From growing peas, Mendel noticed that
offspring did not always have the same traits as the parents
But then the parent’s trait would show up again in a “grandchild,” or 2nd generation
So Mendel began to experiment, attempting to grow peas with certain traits, or characteristics
The Proof is in the PeasThe Proof is in the Peas Peas were an excellent
choice for his research for two reasons
They can self-pollinate, creating offspring with the same traits as the parentOr, they can cross-pollinate with other peas
The ExperimentThe Experiment Mendel looked at one
characteristic at a time (color, height, shape)
If a pea plant has a white flower, then it self-pollinates, you’ll have offspring with white flowers
What happens if a purple-flowered pea plant cross-pollinates a white-flowered pea plant?
Mendel’s DiscoveryMendel’s Discovery Mendel noticed the
offspring of a purple-flowered pea plant and a white one was always purple
BUT, the “grandchildren” or 2nd generation, would have 1 white-flowered pea plant for every three purple ones
Dominant TraitsDominant Traits
Dominant traits are the ones always showing up in the first generation
The purple-flowered pea plant
In a Punnett Square, dominant traits are symbolized by a capital letter
Recessive TraitsRecessive Traits “Fade into the back”
The white-flowered pea plant
These traits reappear in the 2nd generation
MUST be paired with another recessive allele
R r
R RR Rr
r Rr rr
Incomplete DominanceIncomplete Dominance Sometimes, one trait is
NOT dominant over the other
Each allele provides some influence
Hair texture—curly, straight, and wavy—is an example in humans
GenesGenes The instructions for one
particular trait are called a gene
You have 2 forms of the same gene for every characteristic
1 from Mom, 1 from Dad Hair color, eye color,
height, hitchhiker’s thumb, etc.
AllelesAlleles The form of a trait given
by one parent
So, for each gene, you have 2 alleles
Either dominant (capital letter) or recessive (lower-case)
Genotype and PhenotypeGenotype and Phenotype
·Both inherited traits form a genotype
--Aa; rr; etc.·The appearance of a
characteristic is the organism’s phenotype
--a purple flower; wrinkled peas; wavy hair
Genetic Probability and PedigreesGenetic Probability and Pedigrees
Probability is the mathematical chance of an outcome
Aa x Aa has a 25% chance of getting aa as an outcome; 25% AA; 50% Aa
Pedigrees are like family trees for determining the probability of genetic diseases like cystic fibrosis