mendel’s legacy
DESCRIPTION
MENDEL’S LEGACY. CH. 11. Gregor Mendel (1823-1884). The Father of Modern Genetics!. Mendel taught natural science to High School Students. Once: he crossed peas and mice of different varieties “for the fun of the thing”. He determined several “laws” of inheritance.... - PowerPoint PPT PresentationTRANSCRIPT
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MENDEL’S LEGACY
CH. 11
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Gregor Mendel (1823-1884)
The Father of Modern Genetics!
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Mendel taught natural science to High School Students. Once: he crossed peas and
mice of different varieties “for the fun of the thing”
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He determined several “laws” of inheritance....
Mendel’s work became the foundation for Modern Genetics.
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Mendel’s peas
MENDEL chose a common garden pea (Pisum) for his first experiments in hybridization
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Mendel’s Procedure
Step ONE: find plants that are “pure” for one trait (like height).
Call them: P1
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Step TWO: take opposites for the trait (like tall X short) & cross pollinate/fertilize
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Step 3: grow offspring and record results. (F1 = filial = offspring)
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Step 4: Allow self-pollination & grow the grandchildren of P1. Call this group F2. Record results.
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P1 = HH (tall) X hh (short)
Results: All F1 grew tall!
F1 X F1 = F2
Results, 3/4th peas were tall, 1/4th peas were short!
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Mendel discovered...
...some traits are “masked”...they are RECESSIVE and may skip generations.
...some traits are DOMINANT...they occur often in the population.
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...traits are determined by a pair of factors.
Alleles
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Mendel determined...
The pair of “factors” are sorted independently of each other.
These factors are separated when the gametes are formed.
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HOW TO PLAY GENETICS “GAMES” Traits are expressed as letters
of the alphabet. HH or hh Capital letters denote dominant
traits
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HH or hh are pure strains. They are called HOMOZYGOUS
Hh are mixed strains....carriers of the recessive gene, but do not look recessive. They are called HETEROZYGOUS
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EXAMPLES
H = TALL h = short HH = homozygous tall hh = homozygous short Hh = heterozygous tall
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More vocabulary....
genotype = the letters we use to express traits = genetic makeup
phenotype = what something looks like.
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Phenotypes
fat pod, smooth peas
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or...
skinny pods, wrinkled peas