| A | B |
|---|
| histone | a protein around which DNA is tightly coiled. |
| semiconservative replication | When DNA replicates one new strand is created from each ‘old’ strand |
| replication fork | the point at which the DNA double strand starts to unwind. |
| replicon | length of DNA that is replicated following 1 initiation event at the fork. |
| helicase | an enzyme that breaks the hydrogen bonds between the nitrogen bases. |
| Single-stranded binding proteins | stabilize the open DNA formation |
| gyrase | causes the DNA strand to relax as it is unwound to prevent supercoiling. |
| primase | a short segment of RNA that is complementary to a DNA segment. |
| DNA polymerase III | adds to the 5’-deoxynucleotides at the RNA primase site & initiates DNA synthesis. |
| DNA polymerase I | removes the RNA primase after replication. |
| lagging strand of DNA | many points are initiated on the lagging strand, resulting in discontinuous DNA synthesis of this strand. |
| lead strand of DNA | synthesis proceeds from it’s 3’ to 5’ direction of the original DNA strand, creating a continuous new strand of DNA. |
| Okazaki fragments | small pieces of DNA formed during DNA replication that are complementary to are converted into longer strands as synthesis proceeds. |
| ligase | joins the Okazaki fragments by forming phosphodiester bonds. |
| exonuclease | detects & removes mismatched sequences of replicated DNA. |
| DNA transcription | A complementary strand of mRNA created from the DNA strand that will be carried to the ribosome & used as a blueprint for protein synthesis. |
| Wobble hypothesis | rules of base pairing are relaxed at the third position a base can pair with more than one complementary base |
| promoters | Specific DNA sequences that RNA polymerase binds to begin transcription. |
| DNA translation | pairing the complementary tRNA code to mRNA in the ribosome to assemble the correct amino acids for the protein |
| start codon | AUG code for methionine which signals the beginning of translation of mRNA into amino acids for a specific protein |
| stop codon | UAA, UAG, UGA codes which signal the end of translation of mRNA into acids for a specific protein |
| intron | DNA section that does not code for proteins |
| exon | DNA section that codes for proteins. |
| hnRNA | heterogeneous nuclear RNA are pre-mRNA molecules |
| G-caps | 7-methylguanosine is added to the 5' end of mRNA when transcription ends |
| poly-A tails | adenylic acid sequences that are added to the 3’ end of mRNA when transcription ends |
