University:
Duke University
Course:
Biology 154 | AIDS and Emerging Diseases
Academic year:

2024
Views:

280

Pages:

2
Author:

Win Scoot

1 The process of DNA replication is a crucial mechanism in cell reproduction and the inheritance of genetic information. It involves the duplication or copying of the DNA molecule that occurs before cell division. DNA replication takes place with precision and is a complex and well-coordinated process. Here is a detailed explanation of the process of DNA replication: Helicase unwinds the DNA strands: The process of DNA replication begins with the action of the enzyme helicase. Helicase reads and breaks the hydrogen bonds that hold the two DNA strands together, opening the DNA molecule and forming two separate strands. Formation of the replication fork: Once the DNA strands are unwound, the two strands form a structure called the replication fork. The replication fork consists of an initiation site, where replication begins, and a replication bubble, where the DNA strands are duplicated. Primase attaches RNA primers: After the replication fork is formed, the enzyme primase enters and produces short RNA primers. These primers serve as starting points for the DNA polymerase enzymes that will extend the newly formed DNA strands. DNA polymerase extends the DNA strands: DNA polymerase enzymes move along the DNA template strand and extend the new strand by matching free nucleotides. These free nucleotides consist of adenine (A), thymine (T), cytosine (C), and guanine (G), which pair with their complementary base on the template strand (A-T and C-G). DNA polymerase continues to extend the new strand sequentially until it reaches the end of the replication fork. 2 Leading and lagging strand synthesis: DNA replication occurs differently on the two DNA strands. One strand, called the leading strand, can be synthesized continuously as a single long strand. The other strand, known as the lagging strand, is synthesized in short segments called Okazaki fragments. Ligase joins Okazaki fragments: The Okazaki fragments on the lagging strand are joined together by the enzyme ligase. Ligase helps to connect these small fragments by forming phosphodiester bonds between the nucleotides at the ends of the fragments. Repetition at the replication fork: The process of DNA replication continues along the replication fork, where DNA polymerase moves forward and continually extends the new strand as the template strand unwinds. This process continues until the entire DNA molecule is fully duplicated. Proofreading and error correction: During DNA replication, there is a process of checking and correcting errors called proofreading. DNA polymerase enzymes have the ability to recognize and repair mismatched nucleotide pairings on the newly forming strand. This is crucial for maintaining the integrity and accuracy of the duplicated DNA molecule. The process of DNA replication is essential as it ensures that each daughter cell receives an identical copy of the original DNA molecule. This allows for the accurate inheritance of genetic information from one generation to the next. The accuracy and precision of DNA replication are important in preventing genetic errors and mutations that can have negative effects on organisms.

Helicase Unwinds the DNA Strands

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