Term
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Definition
| Telomeric DNA w/overhanging 3' end is bound to telomerase (reverse transcriptase w/its own template RNA). Telomerase enlongates the 3' end by one repeat unit. Primase and polymerase extend the opposite strand 5'-3' and fills in the removed RNA primer. |
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Term
| Human Telomeres and Telomerase |
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Definition
| Telomeres = maintained in germ cells and embryonic cells (high telomerase levels). Adult cells have less telomerase, telomeres get degraded. Leads to cell death (senescence). Cancer cells = increased telomerase. Some premature aging syndromes = lack in telomerase. |
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Term
| Spontaneous damage to DNA |
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Definition
| 1000s of bases lost daily from human cells |
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Term
| Examples of DNA damage induced by radiation and chemicals |
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Definition
| Exposure to UV light: thymine dimer is created when two thymines adjacent bind (skin cancer). RXN w/carcinogen = bulky arene group attached to a base (guanine) (80-90% lung cancer). |
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Term
| Nucleotide excision repair of thymine dimers |
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Definition
| Exinuclease 6 different genes involved, cuts an oligonucleotide when it recognizes a not-flush thymine dimer. Lack of one of the genes = rare skin cancer. |
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Term
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Definition
| Skin cancer = nucleotide excision repair. HPCC = mismatch repair. Breast cancer = recombinational repair of ds breaks. |
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Term
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Definition
| Don't have MutH homolog so the new strand is recognized by working backwards from ss breaks which haven't been ligated yet. |
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Term
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Definition
| Copying a damaged parent strand. Human XPV, special pol, recognizes thymine dimers, puts correct AA bases opposite the dimer, then excision repair replaces the dimer in the parent. |
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Term
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Definition
| Daughter strands remain associated during replication (interphase) so if one gets split by radiation the other daughter can lend its code to the damaged strands. OR the split strand can rejoin but lose some of the bases between the pieces. |
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Term
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Definition
| Two light chains, two heavy chains, each chain w/a constant region and a variable region. Rearrangement of light and heavy chain variable region genes results in 10^11 different antibodies. |
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