DNA Notes

DQ 9 10-19-05

• Why is it important that evidence at a crime scene is collected correctly?

Where is DNA found?

Cell

Nucleus

Nucleus

Chromosomes

Gene

Gene

DNA

Deoxyribonucleic Acid

•Hereditary material that controls all the cell activity and contains info. To make new cells.

During Mitosis

• Cells reproduce, one cell makes an exact copy of itself and then splits apart.

History of DNA

Roslind Franklin

• She created images of DNA molecules using

x-ray. The images suggested a spiral shape.

Watson & Crick

• Built the first model of DNA, won the Nobel Prize Award.

Watson & Crick’s model

DNA Model

• Twisted Ladder called “Double Helix”

• “Handrails”- made up of sugar (Deoxyribose) & phosphate

• “Stairs”- made up of nucleotide bases

Sugar Phosphate

Nucleotide Bases

4 Kinds of bases

• Adenine == A• Guanine == G• Cytosine == C• Thymine == T

Pairs

• Adenine & Thymine (AT)• Guanine & Cytosine (GC)

Every organisms has its own unique DNA

• On the side of your paper. Using the 4 letters in the DNA alphabet. List those 4 letters in any order down the side of your paper. (about 10 letters long)

• Example:» T» T» G» C» A

How DNA copies itself

• 1. An enzyme “unzips” the DNA ladder

Enzyme

• 2. Now have two templates for two new DNA molecules.

1

2

• 3. Free bases now hook up to the two single strands of DNA, now have two exact copies of DNA. T

A G

C