DNA

DNA

DNA Replication

• Ensures that each daughter cell will have the genetic information it needs to carry out its activities

Rosalind Franklin

• Scientist who in 1952 used an x-ray method to photograph DNA molecules

• James Watson and Francis Crick used the photographs to figure out the structure of DNA in 1953

Structure of DNA

• The molecule looks like a twisted ladder.

• Each of the 2 sides of the ladder are made up of molecules of sugar called deoxyribose, which alternates with molecules called phosphates

Multiple Choice

What are the sugar molecules on the sides of the DNA molecule called?

• phosphate

• thymine

• deoxyribose

• cytosine

Structure of DNA

• Each rung of the ladder is made of a pair of molecules called nitrogen bases. They contain nitrogen and other element

• There are 4 kinds of nitrogen bases: adenine, thymine, guanine, cytosine

• We use the first capital letter of each to identify them (A, T, C, G)

Pairing of bases

• Bases on one side of the ladder pair with bases on the other side

• Adenine- Thymine

• Guanine- Cytosine

DNA Replication

• 1. The 2 sides of the DNA molecule unwind and separate (between the paired bases)

• 2. nitrogen bases floating in the nucleus of the cell pair up with bases on each half of the DNA molecule

• 3. The order of the bases in each new molecule exactly matches the order in the original molecule

• 4. Once the new bases are attached, two new DNA molecules are formed