The first step in DNA replication is that the DNA double helix is unwound into two single strands by an enzyme called helicase. While that is a great video to understand the complete system and continuous process of DNA replication, the following video shows each step of the process in more detail: This YouTube video shows how DNA is coiled and folded for compression and also how it is replicated in an assembly line fashion by miniature biochemical machines. Notice that while explaining about DNA replication, it also touches on the process of mutation. The DNA replication and mRNA transcription process are explained in the following video. Transcriptase (type of DNA Helicase), RNA polymerase. In transcription, the codons of a gene are copied into messenger RNA by RNA polymerase.This RNA copy is then decoded by a ribosome that reads the RNA sequence by base-pairing the messenger RNA to transfer RNA, which carries amino acids. The two strands are separated and then each strand's complementary DNA sequence is recreated by an enzyme called DNA polymerase. Transcription is the formation of single, identical RNA from the two-stranded DNA. Replication is the duplication of two-strands of DNA. While in transcription, the end result is a RNA molecule. In replication, the end result is two daughter cells. In this way, the base on the old strand dictates which base appears on the new strand. There are also three 'stop' or 'nonsense' codons signifying the end of the coding region these are the UAA, UAG and UGA codons.ĭNA polymerases can only extend a DNA strand in a 5′ to 3′ direction, different mechanisms are used to copy the antiparallel strands of the double helix. These encode the twenty standard amino acids, giving most amino acids more than one possible codon. The enzyme makes the complementary strand by finding the correct base through complementary base pairing, and bonding it onto the original strand. RNA transcription follows base pairing rules. Since there are 4 bases in 3-letter combinations, there are 64 possible codons (43 combinations). Thesre are then connected with phosphodiester bonds by DNA helix to create a complete strand.Ī 5’ cap is added, a 3’ poly A tail is added and introns are spliced out. In eukaryotes complementary base pair nucleotides bond with the sense or antisense strand. ![]() MRNA, tRNA, rRNA and non-coding RNA( like microRNA) ![]() One strand of DNA becomes 2 daughter strands. Uses the genes as templates to produce several functional forms of RNA The purpose of transcription is to make RNA copies of individual genes that the cell can use in the biochemistry.ĭNA replication is the replication of a strand of DNA into two daughter strands, each daughter strand contains half of the original DNA double helix. The purpose of replication is to conserve the entire genome for next generation. Comparison chart Replication versus Transcription comparison chart
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