DNA Chapter 12

2.What is the relationship between genes and DNA (12-1)? Our genes are made of DNA that store, copy, and transmit information from parent to offspring

3. Structure of DNA 12-2 DNA= deoxyribonucleic acid, long strands of nucleotide bases joined by hydrogen bonds Remember nucleic acids made of nucleotides nucleotides are made of a 5 carbon sugar (deoxyribose), phosphate group, and nitrogenous base 4 types of nitrogenous bases: adenine, thymine, guanine, and cytosine

Structure cont'd... Double Helix-like a twisted ladder following base pairing where Adenine pairs with Thymine and Guanine pairs with Cytosine Chargraff's Rule- % of bases occur in equal amounts 2 strands run in opposite directions

Those involved with the discovery of DNA Structure Early 1950s, Sister Miriam Michael Stimson, chemist that affirmed the structure of DNA bases and the double helix

DNA discovery continued... Franklin, 1952, used X-ray diffraction & produced an X-ray image of DNA, revealing the helix structure

In1953 Watson & Crick "publish" the model of DNA as a double helix

4. DNA Replication 12-3 Copying of DNA for new cells occurs in interphase DNA can be copied because each base on one strand pairs with only one base on the opposite strand. Therefore each half of DNA has the exact information to make exact copies!

The process of DNA replication 1st the DNA is split in 2 strands creating replication forks at the top & bottom DNA polymerase adds complimentary bases to each strand following the base pairing rule Each New DNA molecule has 1 new & 1 old strand

5. How DNA is part of a chromosome?

DNA is wrapped around histone a that create bundles t nucleosomes which coil. Those coils create super coils that make up chromosomes