What does DNA look like? DNA has.. A sugar/phosphate backbone 4 Chemical bases Sugar

DNA Replication Replication bubble Replication fork Replication fork Hydrogen bond Replication occurs during Interphase DNA replication is the process where an entire double-stranded DNA is copied to produce a second, identical DNA double helix.

DNA Replication Helicase unwinds the double helix starting at a replication bubble. The two strands separate as the hydrogen bonds between base pairs are broken. Two replication forks form and the DNA is unwound in opposite directions. DNA helicase

DNA Replication Helicase has completed unwinding the DNA strand. Single strand Binding Proteins (SSB) keep the two strands from re-annealing (coming back together).

DNA Replication PrimaseRNA Primer Primase is an RNA polymerase that makes the RNA primer. These primers “tell” the DNA polymerase where to start copying the DNA. Leading Strand Lagging Strand

DNA Replication DNA Polymerase The DNA polymerase starts at the 3’ end of the RNA primer of the leading stand CONTINUOUSLY. DNA is copied in 5’ to 3’ direction. DNA polymerase copies the lagging strand DIS- continuously. Leading Strand Lagging Strand 3’ 5’ 3’ Direction of Replication

DNA Replication The dis-continuous pieces of DNA copied on the lagging strand are known as Okazaki fragments.

DNA Replication Another DNA Polymerase removes the RNA primers and replaces them with DNA.

DNA Replication Finally the gaps in the sugar phosphate backbone are sealed by DNA ligase There are now 2 identical double helices of DNA. ligase

Mutations The process by which the sequence of base pairs in a DNA molecule is altered.

What is a mutation? Any change in DNA Any abnormal change in genetic material. Some can be inherited by the next generation. Remember that genes are located in DNA!!!

What causes a mutation? 1.) Changes in the environment OR mutagens a. ultraviolet radiation b. pollutants and chemicals c. tar from tobacco 2.) Errors during replication, transcription, or translation

Types of mutations Point mutations small (but significant) changes, often in a single nucleotide base. Deletions remove information from the gene. A deletion could be as small as a single base or as large as the gene itself.

Types of mutations Insertions occur when extra DNA is added into an existing gene. Frame Shift when either addition or deletion of one or two nucleotide bases. When this occurs, the “reading frame” is changed so that all the codons read after the mutation are incorrect.

Guess which type of mutation.. Normal: As the man saw the dog hit the can end it is As the man saw the doT hit the can end Point mutation As the man saw thehit the can end deletion

Guess which type of mutations… As the man saw the FAT dog hit the can end Insertation As the man saw the ogh itt hec ane nd it Frame shift

How else do mutations occur? Errors can occur in the processes of Mitosis or meiosis This is NOT hereditary…. Its just a mistake in procedure!! This is called NONDISJUNCTION The chromosomes fail to separate so you get some homologous chromosomes migration over together instead of separating.