1.Why would cell kill itself(apoptosis) if there is a lot of genetic damage?
2.Please give a report to description the mechanisms of Postreplicative repair and SOS
第二題是問Postreplicative repair and SOS repair運作的機制或產生的原因
- ?Lv 51 0 年前最佳解答
3 題 20 點?!...你每提的東西都超多的
1. Eukaryotic cells have the ability to detect damages and response to damage either by base pair excision or nucleotide excision or error prone repair. However, when too much damage has occurred, the cell is unable to coordinate the DNA repair mechanism because too much DNA has been destroyed either by UV or chemical. This kind of damage will trigger p53 mediated cell apoptosis response, which is a series of active sequences where proteins are synthesized to degrade the entire cell. Apoptosis can happen when a stroke has happened in the brain. Several brain cells will go under apoptosis in order to preserve energy for the rest.
2. Postreplicative (recombination) repair is a Rec A dependent replication recovery. It requires two pairs, 4 strain, of chromosomes. When an error has occurred on one of the chromatin during replication, a single strain gap will be introduced. Rec A will bind to the single strain region and pairs the strain with homologous regions from the sister chromatin in order to fill in the nascent strand gaps via strand transfer. The cross junctions are then resolved so that the both recipient and the donor strain will have normal sequences which can be re-synthesized by replication.
2006-11-13 23:53:44 補充：
SOS repair is known as the error prone repair. It's mediated by din B (pol i), dimA, UmuC, UmuD, Rec A, and Lex A. SOS repair is induced when E coli. is under stress such as UV radiation and a CT dimer formed.
2006-11-13 23:54:50 補充：
When DNA damage occurs, the SOS signal is induced, which RecA coprotease is activated that binds to LexA repressor and promote self cleavage.
2006-11-13 23:55:12 補充：
The release of LexA on the operator or lexA, recA and error-prone polymerase gene induces the expression of these gene, which the synthesis UmuC, UmuD. UmuC/D puts an
2006-11-13 23:55:31 補充：
A as the complementary pair at the C position, allowing the synthesis of DNA to bypass this error and continue the replication. T
2006-11-13 23:57:12 補充：
his error can be fixed either by NTE or BPE on the next round of replication. However, since it's error prone, the CG base pair will be converted into AT pair, which is a type of mutation.
2006-11-13 23:57:38 補充：
2006-11-13 23:58:33 補充：
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