Answer:
A rapidly changing environment
Explanation:
The sexual reproduction is more advantageous to organism to survive in the harsh conditions due to the changes in the sequence of nucleotides of the genes which became a characteristic feature of the sexual mode of reproduction.
This process of changes in the sequence is known as recombination. The sexual mode or reproduction evolved in the last common ancestors of eukaryotes but it is known to occur in the prokaryotes also as they reproduce by conjugation, transformation and transduction.
The sexual mode of reproduction was evolved in the organism as a result of the change in the environment to survive and thrive in the environment.
The mutation occurs in somatic cells from the skin. The mutated cells usually die causing sunburn, in worst cases, it can cause skin cancer. The DNA that is transmitted to the offspring is located in the germinative cells that are not affected.
<span>seafloor spreading
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Explanation:
Okazaki fragments are short sequences of DNA nucleotides (approximately 150 to 200 base pairs long in eukaryotes) which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication.[1] They were discovered in the 1960s by the Japanese molecular biologists Reiji and Tsuneko Okazaki, along with the help of some of their colleagues
During DNA replication, the double helix is unwound and the complementary strands are separated by the enzyme DNA helicase, creating what is known as the DNA replication fork. Following this fork, DNA primase and DNA polymerase begin to act in order to create a new complementary strand. Because these enzymes can only work in the 5’ to 3’ direction, the two unwound template strands are replicated in different ways.[2] One strand, the leading strand, undergoes a continuous replication process since its template strand has 3’ to 5’ directionality, allowing the polymerase assembling the leading strand to follow the replication fork without interruption. The lagging strand, however, cannot be created in a continuous fashion because its template strand has 5’ to 3’ directionality, which means the polymerase must work backwards from the replication fork. This causes periodic breaks in the process of creating the lagging strand. The primase and polymerase move in the opposite direction of the fork, so the enzymes must repeatedly stop and start again while the DNA helicase breaks the strands apart. Once the fragments are made, DNA ligase connects them into a single, continuous strand.[3] The entire replication process is considered "semi-discontinuous" since one of the new strands is formed continuously and the other is not.[4]
[2]During the 1960s, Reiji and Tsuneko Okazaki conducted experiments involving DNA replication in the bacterium Escherichia coli. Before this time, it was commonly thought that replication was a continuous process for both strands, but the discoveries involving E. coli led to a new model of replication. The scientists found there was a discontinuous replication process by pulse-labeling DNA and observing changes that pointed to non-contiguous replication.
