Examination of DNA Structure using Molecular Models
Color diagram of HBB gene from lab manual
Jump to the computer modeling DNA tutorial
and click on "Continue".
Jump to pictures of CPK models
Jump straight to the protein
modeling tutorial (previous experiment)
Jump to color diagrams of details of DNA structure
Jump to web links for gene structure
DNA tutorial
It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material. -J.D. Watson and F.H.C. Crick (1953)
Go to the tutorial and click on "Continue".
CPK model pieces used for nucleic
acids.
For a review of using CPK models see the supplemental information
web page for protein modeling
NOTE: In the figure above, please note that there are different types of carbon and nitrogen atoms used for different purposes. The pieces labeled "aromatic" are used for the purine/pyrimidine rings. These pieces have a small "5" or "6" indicating the number of members in the ring that they will form. Using the incorrect number will result in rings that will not close. To assist you, the sides of the carbon and nitrogen atoms which form the 5 membered rings have been marked with white dots. (The "6" pieces have no dots.) The carbon model piece in the center of the photograph is used for the C=C bond that joins the two member rings of the purine nitrogenous bases (A and G). Please note that the two sides of this double atom piece are not the same. The "flatter" side (less acute angle) forms the 5 membered ring and has been marked with white dots. Two additional pieces shown below are used to form hydrogen bonds (notched and slotted red [oxygen] atoms with one hole, and white [hydrogen] atoms with an indentation that may or may not contain a hook).
Hydrogen bonds were not modeled in that experiment. Special hooked hydrogen atoms and slotted oxygen atoms can be used to join molecules with hydrogen bonds.
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| Line up hooks on special hydrogens with the slots in oxygen (one hole!) atoms. Use hydrogens without hooks to line up with aromatic nitrogens. |
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Diagrams showing orientation of DNA components:
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Orientation of base pairs, sugars, and phosphate groups Stryer
Biochemistry
National Center for Biotechnology Information (NCBI) web page
Entrez Gene entry for the human beta hemoglobin (HBB) gene
Color diagram of HBB gene from lab manual
Live Ensembl Contig view of the HBB gene (good luck, it often doesn't point to the gene), Screen Shot of Ensembl Contig view of the HBB gene
NCBI sequence view of the HBB gene
