During what stage does the DNA copy itself

1 answer:

7 0

Answer: Tightly wound chromosomes, composed of DNA, must unwind before replication. Cell replication splits a cell into two parts, both of which become new, fully functioning cells. Before this can happen, however, cells require a full complement of DNA for each of the new daughter cells that will form as a result of the split. Because of this, DNA makes a copy of itself in a process known as replication during interphase, a stage that occurs before cells divide.

Cell Phases: Mitosis is the process by which parent cells each divide into two identical daughter cells. However, this majority of the cell's time is spent in interphase, during which it performs normal metabolic functions necessary for the organism, such as manufacturing protein. DNA occurs during the S phase of interphase, sandwiched between the G1 and G2 phases. The cell uses checkpoint signals to ensure at the end of G1 that it is big enough to replicate and at the end of G2 to determine whether or not DNA replication has succeeded. If so, the cell can undergo mitosis, at which point DNA winds up tightly for easy transport during the process.

DNA Replication: Replication begins with DNA unwinding and unzipping, its two strands coming apart. While only one side is the “correct” code, containing the actual genetic information used to build the organism’s proteins, both can be the base for a new strand of complete DNA. The enzyme DNA polymerase matches up each base with the correlating base: adenine with thymine and guanine with cytosine. When each pre-existing base has been matched to a nucleotide, which also contains the sugar and phosphate of the DNA’s backbone, the strand is complete.

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Complete question:

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Answer:

In the 1890s, Northern elephant seals were hunted almost to extinction. An unknown population of less than one hundred animals managed to survive on the tiny island of Guadalupe off of Mexico. The current population of over 100,000 is thought to be derived from that tiny remnant population. Compared to the Southern elephant seals (which did not experience such a bottleneck), the Northern elephant seals likely have Lower genetic diversity and Higher levels of genetic diseases.

Explanation:

Genetic drift is the random change that occurs in the allelic frequency of a population through generations. The magnitude of this change is inversely related to the size of the original population. These changes produced by genetic drift accumulate in time. Eventually, some alleles get lost, while some others might set. Genetic drift affects a population and reduces its size dramatically due to a disaster or pressure-bottleneck effect- or because of a population split -founder effect-.

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