DNA Replication

DNA Replication Replication = DNA copies itself exactly (Occurs within the nucleus) Any mistake in copying = mutation DNA mutation = chromosomal mutation

A. Basic Facts of DNA Replication 1. Complementary base pairing makes replication possible C - G A - T

A. Basic Facts of DNA Replication 2. One side of DNA molecule is a template for making the other side (strand) ?’s 1-3

B. Process of DNA Replication Uncoil & unzip DNA molecule Enzyme (-ase) breaks weak Hydrogen Bond between bases

B. Process of DNA Replication 2. Enzyme brings in complementary N-bases DNA Replicase

B. Process of DNA Replication 3. Insert N-bases DNA Replication Tutorial (Go here for on-your-own learning/review) trc.ucdavis.edu/.../week5/06dnareplication.html

Replication Movie C - G A - T

C. Semi-conservative replication Each new DNA molecule contains one old strand & one new strand ?’s 4-6

** DNA Polymerase adds bases in a 5 prime to 3 prime direction, so lagging strand needs a primer to start

DNA Polymerase Works in 5’ to 3’ Direction

Steps of DNA Replication 1. Helicase unzips and unwinds DNA 2. Topoisomerase keeps DNA from becoming tangled ** Leading Strand: works from 5’ to 3’ DNA Polymerase adds bases to old strand ** Lagging Strand DNA Polymerase cannot not directly bind because works from 5’ to 3’ direction, so DNA primase brings an RNA primer, which then sets up the DNA so DNA Polymerase can begin to add bases. This happens in sections called Okazaki fragments that are later glued together by DNA ligase.

Song: https://www. youtube. com/watch Song: https://www.youtube.com/watch?v=P90O5ky3HME Animation: https://www.youtube.com/watch?v=5qSrmeiWsuc https://www.youtube.com/watch?v=27TxKoFU2Nw