word of the day hydrogen bonds: –weak bonds that hold the bases of dna together

Word of the Day

• Hydrogen Bonds:– Weak bonds that hold the bases of DNA

together

History of DNA

Milestones

1869: Johann Friedrich Miescher

• Identifies an acidic substance, of unknown function, in the nuclei of human white blood cells.

• Calls it DNA

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1924

• DNA and proteins are present in the cell’s nucleus.

• Which one is the genetic information?

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No one knows!

1944: Oswald Avery

• Identifies DNA as the genetic material

• Most scientist did not believe that it was the genetic material because DNA is so simple

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1949: Erwin Chargaff

• finds that the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine in DNA from every species.

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1951: Rosalind Franklin

• What did this picture show her?

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1953: James Watson and Francis Crick

• discover the molecular structure of DNA

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DNA Structure:

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1991: Human Genome Project

• Goal: to map out the human genes

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Information Set #1

• *DNA is a polymer. A polymer is a very long, chainlike molecule made of smaller sub unit molecules.

• *These subunits are like links in a chain.

• *They are attached by covalent bonds

• *Four different subunits exist.

Information Set #2

• *DNA consists of two long chains of these 4 subunits

• * The subunits each have a sugar, a phosphate and a base - called a nucleotide

• *These chains are twisted around each other in a double helix. (A helix is the shape a pipe cleaner takes when it is twisted around a pencil)

• * The two chains are held together with weak hydrogen bonds at the bases.

Information Set #3

• *The order of the subunits in one strand determine the order of the subunits in the other strand.

• *The sugar and phosphate form a “backbone” to the polymer.

Assignment: Poster

Title

Vocab List

Paragraph describing structure

Vocabulary words

• Nucleotide

• Nitrogen bases

• Chargaff’s rules

• Double helix

• Hydrogen bonds

• Sugar

• phosphate