Genetics.....the way
to “perfect” the human condition.....??
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Genetics - the good .and the bad
Design-a-Kid
Athletic Ability
Creativity
Intelligence
Bravery
Height, Strength
Cloned human growth hormone
The Fugates of Troublesome Creek (Trost et al, Science 82, 1982).
Too much.....Nitrate
Too Much Growth Hormone
Acromegaly
“Andre the Giant”
Height: 7’4”
Weight: 500 lbs
At 7 feet 8 inches, De-Fen Yao, is considered the world's tallest woman. Her
abnormal growth was due to Acromegaly, a disease resulting from a tumour on the
pituitary gland causing it to pump out excess growth hormone, that inflicted her
when she was 15 years old
Unregulated Production of Growth Hormone
Unregulated Production of Growth Hormone
Unregulated Production of Growth Hormone
Creativity
Virginia Woolf
Vincent Van Gogh
Manic Depression?
Individuals recognized for creativity are ~40x more likely to be diagnosed as manic depressive
Creativity
Bravery
Bravery “Thrill-seeking?”
Genetics - Old and New
Gregor Mendel – the first geneticist
Conducted genetic crosses with pea plants
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Trait Studied Dominant Form Recessive Form
SEED SHAPE
SEED COLOR
POD SHAPE
POD COLOR
FLOWER COLOR
FLOWER POSITION
STEM LENGTH tall dwarf
long stem short stem
purple white
yellowgreen
wrinkledinflated
yellow green
smooth wrinkled
Fig. 11.5, p. 178
carpel stamen
Cross-fertilizing peas
Mendel looked at 34 different physical characteristics (traits) of pea plants that varied among plant populations
Then he made quantitative calculations of these traits as they appeared in subsequent generations
ExampleYellow Seeds (Y) X Green Seeds (y)
Example
All Yellow
Yellow Seeds (Y) X Green Seeds (y)
Yellow: dominantGreen: recessive
Example
All Yellow
Yellow Seeds (Y) X Green Seeds (y)
Self-fertilization Yellow: dominantGreen: recessive
Example
All Yellow
Yellow Yellow Yellow Green
Yellow Seeds (Y) X Green Seeds (y)
Self-fertilization Yellow: dominantGreen: recessive
Example
All Yellow
Yellow Yellow Yellow Green
All Green
Yellow Seeds (Y) X Green Seeds (y)
Self-fertilization Yellow: dominantGreen: recessive
Example
All Yellow
Yellow Yellow Yellow Green
All Yellow All Green
Yellow Seeds (Y) X Green Seeds (y)
Self-fertilization Yellow: dominantGreen: recessive
Example
All Yellow
Yellow Yellow Yellow Green
Yellow Yellow Yellow Green
All Yellow All Green
Yellow Seeds (Y) X Green Seeds (y)
Self-fertilization Yellow: dominantGreen: recessive
Mendel proposed that:
• Traits segregate as discrete units (alleles or genes)
• In diploid organisms, alleles come in pairs (one inherited from each parent)
• If the two alleles in a pair are heterozygous (i.e, different), one allele will be dominant and the other allele will be recessive
• A “homozygous” pair of alleles are the same
• A “heterozygous” pair of alleles are different
• Inheritance of alleles is random
Phenotype the appearance of the organism
Phenotype the appearance of the organism
3 1
Phenotype the appearance of the organism
dominant phenotype
75%
recessive phenotype
25%
3 1
Phenotype the appearance of the organism
Genotype the genetic composition of the organism
dominant phenotype
75%
recessive phenotype
25%
Yy Yy
3 1
Phenotype the appearance of the organism
Genotype the genetic composition of the organism
dominant phenotype
75%
recessive phenotype
25%
Yy Yy
YY Yy Yy yy
3 1
Phenotype the appearance of the organism
Genotype the genetic composition of the organism
dominant phenotype
75%
recessive phenotype
25%
Yy Yy
1 2 1
YY Yy Yy yy
3 1
Phenotype the appearance of the organism
Genotype the genetic composition of the organism
dominant phenotype
75%
recessive phenotype
25%
Yy Yy
1 2 1
hetero-zygous50%
homozygousdominant
25%
homozygousrecessive
25%
YY Yy Yy yy
The Punnett Square: method to determine genotypes of a genetic cross
Y y
Yy Yy
Y
y
YY Yy
Yy yy
One parent
The otherparent
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Mendel's First Law: Two members of a gene pair segregate from each other into the gametes, whereby one half of the gametes carries one of the traits, the other half carries the other.
A Law is "a descriptive generalization about how some aspect of the natural world behaves.... under stated circumstances".Mendel's First Law: Two members of a gene pair segregate from each other into the gametes, whereby one half of the gametes carries one of the traits, the other half carries the other.
Mendel’s Data
Smooth Wrinkled
Mendel’s Data
Smooth Wrinkled
Predicted 750 250
Mendel’s Data
Smooth Wrinkled
Predicted 750 250Observed 751 249 746 254 758 242
Mendel’s Data
Smooth Wrinkled
Predicted 750 250
Too good to be true?
Observed 751 249 746 254 758 242
Trait Studied Dominant Form Recessive Form Dominant-to- Recessive Ratio
SEED SHAPE
SEED COLOR
POD SHAPE
POD COLOR
FLOWER COLOR
FLOWER POSITION
STEM LENGTH
2.96:1
3.01:1
2.95:1
2.82:1
3.15:1
3.14:1
2.84:1tall dwarf
long stem short stem
purple white
yellowgreen
wrinkledinflated
yellow green
smooth wrinkled
Fig. 11.5, p. 178
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Mendel's Second Law: During gamete formation the segregation of one gene pair is independent of all other gene pairs
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