Group Living Has Advantages and Disadvantages

When animals live together in groups such as flocks or herds

Disadvantage- Group promote competition for food and increased transmission of parasites and other diseases.

Advantage - Benefits relate to group defense against predators through increased vigilance and through protection in numbers.

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#Unit 3. Fundamental Processes

oriC also contains 11 GATC/CTAG repeats that are methylated on adenine on both strands.

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#Unit 3. Fundamental Processes

Before replication, the palindromic target GATC site is methylated by dam methylase on the N6 of A of each strand.

Replication generates hemimethylated DNA, in which one strand is methylated and one strand is unmethylated.

Thus, the replication event converts Dam target sites from fully methylated to hemimethylated condition.

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#Unit 3. Fundamental Processes

Dam (Dam-) mutants accumulates hemimethylated products after replication.

If the plasmid is methylated, it undergoes a single round of replication, and then the hemimethylated products accumulate.

Suggesting that a hemimethylated origin cannot be used to initiate a replication cycle.

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#Unit 3. Fundamental Processes

Only fully methylated origins can initiate replication;

hemimethylated daughter origins cannot be used again until they have been restored to the fully methylated state.

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#Unit 3. Fundamental Processes

The GATC sites AT THE ORIGIN remain hemimethylated for 13 minutes after replication called as refractory period of replication cycle or delay time.

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#Unit 3. Fundamental Processes

At typical GATC sites elsewhere in the genome, remethylation begins immediately (1.5 minutes) following replication.