Brings in the correctnucleotides and matchesthem up.
MitosisDNA replication occurs during the synthesis phase. InDNA replication helicase untwists the double helixand the leading strand separates from the laggingstrand. Then DNA polymerase brings in the correctnucleotides to build the other halves of DNA. Finallyit twists back up into a double helix and you have twoidentical strands of DNA.
Why Does DNA Copy?DNA needs to copy so that all of your cells have thesame exact copy of DNA and have the right geneticinformation.
Telomeres are the junk ends of DNA.Okazaki fragments are on the lagging strand of DNA.They are placed on the DNA strand in fragments andDNA ligase is the enzyme that stitches themtogether.
Telomerase and CancerTelomerase is an enzyme that adds more telomeresto the 3’ end of DNA.Cancer cells can produce their own telomerase, sothey have enough telomeres to grow indefinitely.Using a substance that prevents the action oftelomerase may help fight cancer, but it may alsoharm our other cells.
Transplant CellsTransplant cells die out after a few mitotic divisionsand you need to add more.If the cells are transformed with a telomerase geneand a therapeutic gene they should be able to divideforever.There are certain studies to see if it would causecancer.
CloningWhen cells are cloned, their telomeres are shorterthan normal because they have been deprived oftelomerase while they were cultured.This shortens their life spans.
Cell AgingA cell’s life span depends on the length of theirtelomeres.A cell with longer telomeres can undergo mitosismore than on with shorter telomeres can. Certain cells, like cancer cells are able to maintainthe length of their telomeres with the help oftelomerase. This means that they can divideindefinitely.