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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