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How is DNA replicated?
How does DNA replication occur in eukaryotes?
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Replication proceeds bidirectionally from origins and terminates when replication forks from adjacent active origins meet (iv). The origin of replication (also called the replication origin) is a particular sequence in a genome at which replication is initiated. [1]
- Definition
- Background
- DNA Replication Process
- Prokaryotes vs. Eukaryotes
- DNA Repair and Damage
- Conclusion
DNA replication is a process that occurs during cellular division where two identical molecules of DNA are created from a single molecule of DNA. As a semiconservative process, a single molecule containing two strands of DNA in double helix formation is separated, where each strand serves as a template for the new DNA molecules. Because the double ...
Deoxyribonucleic acid, known simply as DNA, is the blueprint of all living things. DNA contains genes that code for the physical and metabolic information expressed in an individual while having the potential to be passed down to future offspring. Almost all cells have DNA, which is typically stored in the nucleus. Notable cells that lack DNA inclu...
Proteins in DNA Replication
DNA replication is highly regulated and requires multiple proteins to run efficiently. A majority of these proteins act as stabilizers and enzymes, with enzymes being proteins that behave as catalysts to create and speed up biochemical reactions. Some of the major proteins in DNA replication include the following: Helicase: An enzyme that opens the double helix by breaking the hydrogen bonds between complimentary base pairs Single-strand DNA- binding proteins (SSBPs): These proteins stabilize...
The Replication Bubble
When DNA begins to replicate, a replication bubble is formed that can be detected visually by electron microscopy. A specific sequence of bases- known as theorigin of replication– determines where this replication bubble begins. Inside of the bubble, two Y-shaped replication forksresult where DNA is actively replicated on either side of the region. The replication forks are formed as the double strands of DNA are separated by helicase in both directions away from the origin of replication. It...
Replicating the Leading Strand
As mentioned previously, DNA strands have an anti-parallel nature, where one strand will run 3’-5’ and the other will run opposite from 5’- 3’. DNA polymerase can only synthesize new strands of DNA in the 5’-3’ direction. In order for DNA polymerase to do this, it must read the template strand from 3′-5′. Therefore, replicating the template strand that runs 3’-5’ results in the synthesis of the leading strand. The leading strand is a new strand of DNA that is synthesized in a single, continuo...
DNA replication overall is fairly conserved across life. However, general differences exist in the enzymes and mechanisms used, as well as time required between species. The largest differences are between the domains of prokaryotes (bacteria and archaea) and eukaryotes (all other plant and animal cells). Minor differences between these groups incl...
Incorrect Replication
DNA replication must be fast, but it must also be extremely accurate. DNA replication occurs trillions of times in a single human. Even if there was only a single mistake in each replication, that would add up to trillions of errors that could be detrimental to the individual’s life. So how are mistakes regulated? The first way this is done is by DNA polymerase proofreading its own work. Each complimentary pair of nucleotides has a distinct shape. Therefore, when the wrong base is placed, the...
Environmental Damage
Environmental factors- such a UV radiation, X-rays, and chemical exposure- can damage DNA. For example, UV radiation found in sunlight and tanning booths can create a thymine dimer where two thymine bases next to each other form a covalent bond. This thus creates a bump in the DNA strand that prevents DNA polymerase from synthesizing past this point. These circumstances can become detrimental, and systemsmust be put into place to repair damages such as this. In the case of the UV radiation, e...
DNA replication is a highly regulated molecular process where a single molecule of DNA is duplicated to result in two identical DNA molecules. As a semiconservative process, the double helix is broken down into two strands, where each strand serves as the template for the newly synthesized strand by matching complementary bases. Because DNA polymer...
Mar 17, 2022 · There are multiple origins of replication on the eukaryotic chromosome, such that replication can occur simultaneously from several places in the genome. During elongation, an enzyme called DNA polymerase adds DNA nucleotides to the 3' end of the template.
Feb 17, 2023 · DNA replication starts at a particular location on the DNA, called the origin of replication. It is the region where the DNA is unzipped. They have a specific sequence covering about 245 base pairs, mostly A/T base pairs and fewer GT-base pairs.
Oct 31, 2023 · Eukaryotic chromosomes have multiple origins of replication, which initiate replication almost simultaneously. Each origin of replication forms a bubble of duplicated DNA on either side of the origin of replication.
Initiation and Unwinding. During initiation, so-called initiator proteins bind to the replication origin, a base-pair sequence of nucleotides known as oriC. This binding triggers events that...
Sep 12, 2019 · DNA synthesis of daughter strands starts at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, organisms have evolved surprisingly divergent strategies that control replication onset.
