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Shoemaker dna replication
- 1. DNA replication By: Kim Shoemaker
- 2. Key: • Thymine • Adenine • Cytosine • Guanine • Phosphate • Sugar • Helicase Binding protein
- 3. DNA replication occurs during the S phase of mitosis. 5 ’ phosphate sugar phosphate Thymine Adenine phosphate sugar Cytosine Guanine Guanine Cytosine Adenine Thymine Adenine Thymine Guanine Cytosine Thymine Adenine sugar sugar phosphate Cytosine Guanine phosphate 3 sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar base make up a nucleotide. Each base pair is linked by a hydrogen bond and these bonds are easily broken. phosphate phosphate sugar sugar 3 ’ The phosphate, sugar and sugar phosphate Guanine Cytosine sugar 5
- 4. 5 ’ On the lagging strand, that stretches away from the replication fork, DNA polymerase Phosphate sugar Phosphate Thymine sugar Adenine Phosphate Phosphate sugar Cytosine sugar Guanine Guanine Cytosine Phosphate Phosphate This is the leading strand. sugar Guanine sugar Phosphate Binding proteins sugar Adenine bind to a singlestrand DNA for Phosphate stabilization. sugar Adenine Thymine sugar Phosphate Thymine sugar Phosphate Helicase Cytosine Thymine Adenine Phosphate Cytosine sugar sugar Phosphate Phosphate sugar sugar Guanine This is the lagging strand. sugar Phosphate Guanine sugar Phosphate Phosphate 3 DNA primase marks a starting point with an RNA primer to the lagging strand. Double stranded DNA is “unzipped” by DNA helicase. Helicase unwinds doublestranded DNA at the origin of replication by breaking the weak hydrogen bonds between the two strands. Phosphate Phosphate sugar 3 ’ Cytosine sugar 5
- 5. phosphate sugar Cytosine phosphate Binding protein phosphate Adenine Thymine phosphate Adenine Thymine phosphate sugar phosphate Guanine Binding protein sugar Binding protein Binding protein phosphate Binding protein sugar Guanine phosphate Guanine Binding protein phosphate Cytosine phosphate sugar phosphate Thymine Adenine sugar phosphate phosphate Cytosine Guanine phosphate 3 sugar phosphate Cytosine Binding protein Adenine Binding protein Thymine 3 ’ Binding protein sugar phosphate sugar Binding protein Binding protein phosphate Binding protein 5 The DNA is split ’ and is now two half strands of DNA that need to have the correct base pairs put together. Guanine goes with cytosine and thymine goes with adenine. The bases are also represented by letters guanine is G, cytosine is C, thymine is T, and adenine is A. phosphate Guanine Cytosine sugar 5
- 6. 5 ’ phosphate sugar phosphate Thymine Adenine phosphate sugar phosphate Cytosine Guanine Guanine Cytosine phosphate sugar Adenine Thymine Adenine Thymine Guanine Cytosine Thymine Adenine sugar sugar phosphate Cytosine Guanine phosphate 3 sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar 3 ’ sugar phosphate Guanine Cytosine sugar 5 The base pairs are added by polymerase III from 5’ to 3’ direction to a single stranded DNA molecule. On the lagging strand , that extends away from the replication fork, DNA Polymerase III forms okazaki fragments in a descontinuous fashion with the help of other enzymes. DNA Primase marks a starting point in the form of an RNA Primer. DNA Polymerase II and then adds nucleotides and forms okazaki fregments. When DNA Polymerase II reaches the RNA primer from the fragment before, DNA Polymerase I turns the RNA to DNA. Then DNA Ligase forms a phophodiester bond to finsih the connection of okazaki fragments.
- 7. 5 ’ phosphate sugar phosphate Thymine Adenine phosphate sugar phosphate Cytosine Guanine Guanine Cytosine phosphate sugar Adenine Thymine Thymine sugar Guanine Cytosine phosphate sugar Adenine Cytosine Guanine sugar sugar sugar sugar Guanine Cytosine Thymine Adenine Cytosine Guanine Guanine Cytosine Adenine Thymine Adenine Thymine Guanine Cytosine sugar Thymine Adenine 5 3 sugar sugar phosphate Cytosine Guanine phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar 3 ’ phosphate phosphate phosphate phosphate 3 sugar phosphate phosphate sugar sugar phosphate Thymine sugar phosphate phosphate When a base isn’t put with it’s correct base pair it forms a mutation and if the mutation isn’t fixed then the DNA will be changed and replicated and the mutation will become the regular DNA and this causes evolution. phosphate phosphate Then there are two identical strands of DNA. sugar phosphate Adenine 5 ’ sugar phosphate phosphate sugar sugar phosphate phosphate sugar sugar 3 ’ phosphate sugar phosphate Guanine Cytosine sugar 5
- 8. At the end of our genes there are telomeres and they protect our genetic data and makes it possible for a cell to divide. Every time a cell divides the telomeres get shorter and when they become too short the cell can’t divide, it becomes inactive or it dies and the shortening process is associated with a higher risk of death, aging and cancer. The enzyme telomerase adds bases to the telomeres so they don’t become to short and when the cell continues to divide the cell we slowly run out of telomerase and telomerase is always in reproductive cells so the next organism has telomerase to keep the organism alive and without telomerase in the reproductive cells the living things without it would go extinct. We can use telomerase to make human cells immortal and would be able to mass produce cells for transplantation like insulin producing cells to cure diabetes, skin cells to heal burns and wounds, and cartilage cells for some types of arthritis. There are people trying to clone human telomerase.