Objectives

• Explain how the structure and replication of DNA relates to heredity and protein synthesis.

The Discovery of DNA & Heredity

• How cells know how to produce your body, ATP, glucose, NADPH, chlorophyll, green eyes, noses, and fingers

• The passing on of the plans to make body parts from parent to child is called Heredity

• We use a recipe to make chocolate cake

• Builders use blueprints to make a house

• What does the body use to make noses, hands, brains, and other body parts?

• DNA (deoxyribonucleic acid)

• How was this discovered?

Frederick Griffith 1928

• Took two types of pneumonia bacteria and gave them to mice– Smooth bacteria caused

pneumonia

– Rough bacteria didn’t cause pneumonia

• Killed smooth bacteria and gave to mice but mice lived

• Killed the smooth bacteria and mixed the contents with a rough live bacteria. The mice died.

• Somehow the rough bacteria had received an ingredient from the smooth that caused the mice to get pneumonia.

1944 Avery, McCarty,Mcleod• Case 1:Took extract from killed bacteria,

destroyed the lipids, proteins, carbohydrates.

• Result: Bacteria still caused pneumonia.• Case 2: He destroyed RNA and gave

cytoplasm but mice still got pneumonia.• He destroyed DNA and gave cytoplasm to

mice and the mice lived!– Conclusion: DNA causes pneumonia.

Hershey & Chase 1952

• Injected radioisotopes into Proteins & DNA. Mice cells that died had no sulfur from proteins, but did have Phosphorus from DNA.

Franklin & Wilkins 1950

• X rayed DNA.

• Found it was a twisted ladder and has regularly spaced segments.

Chargaff 1950

• Found nitrogen bases on DNA were in equal proportions.

• Adenine pairs with Thymine

• Cytosine pairs with Guanine.

Watson and Crick 1953

• Made the first 3D model of DNA showing it was a double helix.

DNA from Peas

• Blender

• Peas, Detergent, Meat tenderizer, Salt

• Isopropyl alcohol and glass rod.

Draw a picture of DNA

• Label each side and nitrogen bases.

• Or make a model out of anything creative and label the parts.