| A | B |
|---|
| Deoxribonucleic acid(DNA) | controls production of proteins within the cell |
| Proteins | form structural units of cells and help control chemical processes within the cell |
| DNA's primary functions | 1) to store and use information to direct activities of cells 2)copy itself exactly for new cells |
| DNA and RNA | complex organic molecules composed of polymers |
| Polymers | repeating subunits or monomers |
| What are nucleotides made of? | five carbon sugar, phosphate group, nitrogen base |
| Bases | adenine, guanine, thymine, cyntosine |
| Purines | adenine and guanine;double ring of carbon and nitrogen atoms |
| Pyrimidines | thymine and cytosine; single ring of carbon and nitrogen atoms |
| Double Helix | 2 strands that twist around a central axis |
| Who discovered the structure of DNA? | James Watson and Francis Crick in 1953 |
| Individual nucleotides | connected-covalent bonds between sugar and phosphate |
| Sides | alternating sugar and phosphate untis |
| Rungs | pairs of nitrogen bases |
| Hydrogen bases | hold 2 strands together |
| Adenine pairs with: | thymine |
| Cytosine pairs with: | guanine |
| Adenine complements thymine | forms 2 hydrogen bonds |
| cytosine complements guanine | forms 3 hydrogen bonds |
| Replication | process of duplication of DNA |
| Step 1 | DNA helicase attaches to DNA-"unzips" the 2 strands; breaks hydrogen bonds |
| Replication Fork: | point at which 2 chains separate |
| Step 2 | unpaired bases react with complementary bases of nucleotides; forms hydrogen bonds |
| Step 3 | DNA polymerase speeds up formation of sugar |
| Step 4 | 2 new DNA molecules |
| Copying | simultaneously at many points on molecule- permits faster replication |
| Replication | high degree of accuracy- 1 error in every 10000 paired nucleotides |
| Mutation | change in nucleotide sequence |
| Factors that damage DNA | body heat, radiation, chemicals |
