DNA replication facts for kids
DNA replication is how a cell makes an exact copy of its DNA. Think of it like making a photocopy of an important instruction manual. This process is super important for life. It happens every time a cell divides.
When DNA copies itself, it's called "semi-conservative." This means each new DNA molecule is half old and half brand new. It uses one original strand as a guide.
DNA replication happens in all living things that have DNA. There are small differences in how it works in simple cells (like prokaryotes) and more complex cells (like eukaryotes).
In a cell, DNA replication starts at special spots called origins. The DNA strands then unwind, like a zipper opening. This creates a Y-shape called a replication fork. Many tiny helpers, called enzymes, work together here. They make sure the new DNA strands are built correctly.
What is DNA Polymerase?
DNA polymerases are a group of enzymes that do all the work of copying DNA. They are like tiny builders. However, a DNA polymerase can only add new pieces to an existing DNA strand. It cannot start a new strand from scratch.
To begin building, a short piece of DNA or RNA is needed. This short piece is called a 'primer'. The primer attaches to the original DNA strand. Then, the DNA polymerase can start adding new nucleotides.
DNA polymerases are usually very accurate. They make less than one mistake for every 10 million pieces they add! Some DNA polymerases can even 'proofread' their work. This means they can remove wrong pieces and fix mistakes as they go.
How Cells Repair DNA
DNA inside our cells can get damaged all the time. Luckily, cells have many ways to fix this damage. The control center of cells (the nucleus) has special repair systems. These systems fix almost all the damage that happens.
A large group of DNA repair enzymes are always checking the DNA. They look for any damaged pieces. When they find a problem, they quickly fix it. This helps keep our DNA healthy and working correctly.
Images for kids
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Role of initiators for initiation of DNA replication.
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Formation of pre-replication complex.
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The assembled human DNA clamp, a trimer of the protein PCNA.
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E. coli Replisome. Notably, the DNA on lagging strand forms a loop. The exact structure of replisome is not well understood.
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Replication fork restarts by homologous recombination following replication stress
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Epigenetic consequences of nucleosome reassembly defects at stalled replication forks
See also
In Spanish: Replicación de ADN para niños
