Term
| how does the cell makes sure DNA polymerase stays on template long enough to replicate DNA? |
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Definition
| sliding clamp protein attaches to template and polymerase |
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Term
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Definition
| clamp loading protein and energy from ATP |
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Term
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Definition
| beta subunit of DNA polymerase 3 |
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Term
| DNA polymerase 1 catches mistake in DNA: |
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Definition
exonuclease activity of 3’ – 5’ error correction
When enzyme notices error it slides backwards
-has 3 active sites: one to add nt and one to remove nt if error.
- 3’ end of newly synthesisized DNA is taken off |
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Term
Finishing rep in bacteria
-termination site-- OriC site.
-- sequences are -- |
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Definition
opposite
The Ter sequences (TerA thru TerF) are positioned on the chromosome in clusters w/ opposite orientations |
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Term
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Definition
| separaes the 4 catenated strands to be able= two new circular chromosomes and E. coli is divided |
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Term
| End of replication problem: |
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Definition
| Lagging strand runs out of space for primer (not enough room for okasaki fragment to form )= shortened dna aby 25-200 bp per cell division- many genes located adjacent to telomeres (at the end of chromosomes) |
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Term
| Shortening of chromosomes leads to: |
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Definition
| Leads to apoptosis= programmed cell death and likely to senescence. |
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Term
| solution to end of rep problem: |
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Definition
| Telomerase- adds nt to the TEMPLATE strand- lengthen the template strand adds nt to 3’ end of template. |
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Term
| DNA polymerase requires a primer to elongate DNA; this means that the RNA primer that begins at the end of the entire linear chromosome will never be able to be replaced with DNA (because there is nothing preceding it for the DNA polymerase to attach to). This will result in a |
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Definition
| 3 overhang at each end of the chromosome because the 3 end of the duplex will be longer than its 5 complementary piece. |
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Term
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Definition
| RNA-dependent DNA polymerase = a reverse transcriptase; i.e., RNA is the template |
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Term
| Telomerase has RNA with CyAx repeat to serve as template for synthesis of the |
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Definition
| TxGy strand of the telomere |
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Term
| Telomerase binds to the 3’-end of the chromosome and |
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Definition
| hangs off so that the RNA template extends beyond it |
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Term
| Telomerase extends the 3'-end, using |
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Definition
| the RNA of the enzyme as the primer |
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Term
| Telomerase makes a -- with 3' overhang to protect it from nucleases bc it is -- to form a -- |
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Definition
loop
ss
T-loop, a loop of DNA that contains the original duplex in addition to the 3 overhang, all hybridized to each other. |
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Term
| Human telomeric DNA= -- long, final- |
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Definition
| 3-20kb long, final overhang =300nt |
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Term
| --- is major factor in apoptosis (= programmed cell death) and likely in senescence |
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Definition
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Term
| How many bp lost per cell division |
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Definition
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Term
| Which cells have high telomerase activity? |
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Definition
| sperm cells, nails, skin, hair, bone marrow and CANCER |
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Term
| What makes cells immortal? |
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Definition
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Term
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Definition
• Harmful (e.g., cancer)
• Silent (= no change in amino acid)
• Neutral (= change in amino acid has little effect; e.g., often: K and R or D and E)
• Beneficial (rare but basis for much of evolution) |
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Term
| How many molecular lesions per cell per day? Which is how many lesions per day per human adult? |
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Definition
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Term
| • Large amount of DNA damage causes cell to enter: |
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Definition
• Senescence = an irreversible state of dormancy
• Cell suicide = apoptosis = programmed cell death
• Unregulated cell division, which can lead to the formation of a cancerous tumor |
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Term
| Systems of proteins in cells that repair DNA damage to reduce mutagenesis must: |
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Definition
• Recognize the lesion
• Remove the damaged nucleoside(s)
• Synthesize missing DNA
• Ligate the strands back together (DNA ligase) |
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Term
| example of Deficiency of DNA repair cause of several diseases |
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Definition
| BRCA1 and 2 genes related to hereditary breast cancer |
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Term
| Deinococcus radiodurans = worlds toughest bacteria bc: |
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Definition
| enhanced dna repair system make it resistant to damage from radioactivity |
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Term
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Definition
| minor modifications to bases or abasic sites |
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Term
nucleotide excision repair
*only one we went over |
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Definition
| bulky adducts and pyrimidine dimers |
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Term
| double-strand- break repair |
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Definition
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Term
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Definition
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Term
| Steps to Nuclotide exiscion repair: |
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Definition
| 1 An excinuclease binds to DNA at the site of a bulky lesion and cleaves the damaged DNA strand on either side of the lesion. 2 The DNA segment—of 13 nucleotides (13 mer) or 29 nucleotides (29 mer)—is removed with the aid of a helicase. 3 The gap is filled in by DNA polymerase, and 4 the remaining nick is sealed with DNA ligase. |
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