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| Question | Answer |
| What is the structure of a nucleotide? | |
| What are the bases for DNA and RNA? | DNA: adenine, guanine, thymine and cytosine RNA: adenine, guanine, uracil and cytosine |
| What is the structure of a polynucleotide? | The phosphate groups are bonded onto the pentose sugar by phosphodiester bonds |
| What is the structure of DNA? | A double helix structure, where two polynucleotide strands bond together. This happens because the complimentary bases pair (CG, AT or AU) to form hydrogen bonds between them, and this forms two antiparallel strands |
| What's the difference between RNA and DNA? | RNA has a ribose sugar, and DNA has a deoxyribose sugar. DNA also contains only A, T, C and G bases, whereas RNA has only A, U, C and G bases. RNA is also relatively short, and single stranded. |
| How is DNA replicated? | The DNA helix unwinds and DNA helicase breaks the hydrogen bonds between bases. As this is happening, free-floating DNA nucleotides join to the single strand, and DNA polymerase joins the two new strands together. |
| What is DNA replication called and why? | Semi-conservative replication, because two new molecules are created with one strand from the original DNA and one is new. |
| What is the evidence for semi-conservative replication? | Meelson and Stahl raised bacteria in light nitrogen, and then placed into heavy nitrogen. When the DNA was spun in a centrifuge, it contained both heavy and light nitrogen |
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