DNA Replication and Mutation Boston University复制与突变波士顿大学.pptVIP

DNA: Replication and Mutation What is DNA? DNA = deoxyribonucleic acid DNA is the “blueprint” for the cell ?contains the instructions that tells the cell how to do things and what to make DNA is like blueprints for making a city, which in this case is the cell What is DNA made of? DNA is made up of 4 bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G) Structure of DNA DNA is made up of two strands (double stranded) Each strand has the bases connected to a PHOSPHATE BACKBONE The two strands wrap around each other in a winding staircase manner (helix) Models of DNA ACTUAL Pictures of DNA DNA Replication In order for you to survive, your cells need to replicate themselves. In order for them to do that, they need to replicate their DNA Every cell in your body has the same DNA, because every time one of your cells divides, it makes a copy of its DNA to give to the new daughter cells How does DNA replicate? The DNA is unzipped and the original strands are used to help make the new molecules – See Demonstration What are mutations? MUTATIONS are any changes in the sequence of bases of DNA How do mutations occur? Sometimes during replication, the cell makes a mistake and adds the wrong base When the cell replicates its DNA again, the two strands that are produced are no longer exactly the same This usually will cause the new cell to die, but sometimes it can cause the cell to divide when it is not supposed to ? cancer How do mutations occur? What can cause mutations to happen more often? * * RED = COPY INTO NOTEBOOK Amoeba Cell Rules for DNA Bases: 1. A pairs with T 2. G pairs with C “Chargaff’s Rules” Mutations DO NOT lead to this Mutations COULD lead to this Colon cancer cells Replication *