Term
| What is attached to the 3' and 5' carbon of deoxyribose in DNA? |
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Definition
3' has OH
5' has phosphate |
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Term
| How are nucleotides bound together? |
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Definition
| 5' nucleotide ends bind to 3' nucleotide ends through phosphodiester bonds. Two phosphate groups are released out of the three that were on the 5' carbon. This energy is used to drive the reaction. |
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Term
| What are origins of replication? How do they relate to replication forks? |
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Definition
Origins of replication are where the two strands are separated and replication begins. A replication bubble forms, the forks are at either end of the bubbles.
Eventually the bubble will merge with another bubble down- or upstream in the DNA. |
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Term
| What is the difference between the leading and lagging strand in DNA replication? |
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Definition
The leading strand of DNA is the one where the new strand using the outer as a template is going in the 5' to 3' direction (the direction DNA must be made in)
The lagging strand is where the new strand using the outer as a template is going in the 3' to 5' direction. Since they cannot be made in this direction, small fragments called Okazaki fragments are made in the 5' to 3' direction and added together. |
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Term
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Definition
| DMA polymerase can't start a strand, it can only add nucleotides (dNTP) in the 5' to 3' direction of an existing strand. Therefore, an RNA primer made by primase is used by polymerase to begin the DNA strand. |
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Term
| What role does DNA pol. play in DNA replication? |
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Definition
| DNA poly. replaces RNA primers with DNA strands. |
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Term
| What purpose do telomeres serve in DNA replication? |
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Definition
| Because DNA poly. can't replace the RNA primer at the beginning of DNA (beause it needs a strand already there to start it), the first sequence of genes in all DNA is a telomere - "junk DNA." The RNA primer just comes off and the DNA strand gets shorter. |
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Term
| Name two ways DNA poly. repairs DNA. |
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Definition
1. Mismatch repar - poly. proofreads the DNA, if there is a mismatched nucleotide, it replaces it.
2. Excision repair - Repairs damaged regions of DNA by cutting it out. DNA poly. and ligase refill the gap. |
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