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Life functions through the specialized chemistry of carbon and water, and builds largely upon four key families of chemicals: lipids for cell membranes, carbohydrates such as sugars, amino acids for protein metabolism, and nucleic acid DNA and RNA for the mechanisms of heredity. Any successful theory of abiogenesis must explain the origins and ...
Eukaryotes initiate DNA replication at multiple points in the chromosome, so replication forks meet and terminate at many points in the chromosome. Because eukaryotes have linear chromosomes, DNA replication is unable to reach the very end of the chromosomes. Due to this problem, DNA is lost in each replication cycle from the end of the chromosome.
A scenario is a set of related concepts pertinent to the origin of life (abiogenesis), such as the iron-sulfur world. Many alternative abiogenesis scenarios have been proposed by scientists in a variety of fields from the 1950s onwards in an attempt to explain how the complex mechanisms of life could have come into existence. These include ...
In DM1 the DNA sequence that is expanded is CTG while in DM2 it is CCTG. These two sequences are found on different genes with the expanded sequence in DM2 being found on the ZNF9 gene and the expanded sequence in DM1 found on the DMPK gene. The two genes don't encode for proteins unlike other disorders like Huntington's disease or Fragile X ...
A possible explanation of the origin of viroids sees them as "living relics" from a hypothetical, ancient, and non-cellular RNA world before the evolution of DNA or of protein. [ 13 ] [ 14 ] This view, first proposed in the 1980s, [ 13 ] regained popularity in the 2010s to explain crucial intermediate steps in the evolution of life from ...
The total result is formation of two new double stranded DNA sequences that are exact copies of the original double stranded DNA sequence. [ 1 ] In terms of structure, the replisome is composed of two replicative polymerase complexes, one of which synthesizes the leading strand , while the other synthesizes the lagging strand .
Unlike linear molecules, circular chromosomes are able to replicate the entire molecule. However, the two DNA molecules will remain linked together. This issue is handled by decatenation of the two DNA molecules by a type II topoisomerase. Type II topoisomerases are also used to separate linear strands as they are intricately folded into a ...
DnaA is a protein that activates initiation of DNA replication in bacteria. [1] Based on the Replicon Model, a positively active initiator molecule contacts with a particular spot on a circular chromosome called the replicator to start DNA replication. [2] It is a replication initiation factor which promotes the unwinding of DNA at oriC. [1]