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The History of DNA
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Slide 1

The History of DNA

The History of DNA

The scientists who discovered Dna

Slide 2

Gregor Mendel

Gregor Mendel

Austrian monk

Born in 1822

In monastery known for

research and teaching

After his death (1884) acknowledgment of his

discoveries in 1900

Known as ďThe Father of Geneticsď

Slide 3

Mendelís Pea Plants

Mendelís Pea Plants

First scientist to describe how traits are inherited

Looked at pea plants for 8 years

He studied 9 generations of plants

Slide 4

Mendelís Observations

Mendelís Observations

He noticed that peas are easy to breed for pure traits and he called the pure strains purebreds.

He developed pure strains of peas for seven different traits (i.e. tall or short, round or wrinkled, yellow or green, etc.)

He crossed these pure strains to produce hybrids.

Slide 5

Mendelís Results

Mendelís Results

Mendel crossed purebred tall plants with purebred short plants and the first generation plants were all tall.

When these tall offspring were crossed the result was a ratio of 3 tall to 1 short.

Slide 6

The Traits Mendel Looked At

The Traits Mendel Looked At

Slide 7

Dominant Trait Rule

Dominant Trait Rule

Strong Hereditary traits cover weak traits.

Mendel called stronger traits

DOMINANT Ė Represented by CAPITAL LETTER (T)

Mendel called weaker traits

Recessive Ė Represented by lower case letter (t)

Slide 8

Fredrick Griffith

Fredrick Griffith

Worked in the 1920ís

Taxonomist Ė a scientist who classifies and names organisms Ė He specialized in pathogens (disease-causing organisms)

Used mice and bacterium (Streptococcus pneumonia) to see if inherited material is passed though DNA or protein.

Slide 9

Oswald Avery

Oswald Avery

Continued Griffithís work

Identified DNA as the material that passes on the inherited information.

He used large amounts of bacteria and a process of heating and mixing the liquids to extract the nitrogen bases away from the protein

Became worldís first genetic engineer

Slide 10

Erwin Chargaff and his rule

Erwin Chargaff and his rule

In 1950, biochemist Erwin Chargaff found that the arrangement of nitrogen bases in DNA varied widely,

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