CELL BIO - Chapter 6: DNA replication

only first part of chapter 6 since its all that's gonna be on the exam :P

Helicase

Enzyme that unzips DNA. Uses the energy of ATP hydrolysis. Pries apart ahead of replication fork.

Polymerase

Replicates DNA from the 3’ end. Can also proofread nucleotides as they are added.

Primase

Makes primer (starting line) out of RNA so polymerase knows where to replicate. Starts from 3’ end of the original strand/5’ of the new strand. Gets removed at end of cellular replication since it’s RNA not DNA, which leaves gaps

Ligand

Reconnects replicated DNA fragments on lagging strand by filling in gaps left by primase

SSB (single stranded binding proteins)

Keeps single stranded DNA halves separate

Topoisomerase

Prevents DNA from supercoiling by making transient breaks in one strand of the DNA double helix

Sliding Clamp

Keeps polymerase attached

Clamp Loader

Locks sliding clamp onto DNA strand. Uses energy of ATP hydrolysis

Okazaki Fragments

Chunks/fragments of replicated DNA created by the lagging DNA strand being unable to create a continuous strand

Histone

Protein “spools” that DNA winds around

Nucleosome

Structural unit created when DNA winds around (eight?) Histones

Chromatin

Condensed bundles of nucleosomes. Forms during cell division.

Chromosome

Tightly coiled structural units made of chromatin that code for genetic information. Set number within cells, exists when cells begin to divide

Structural order of DNA

DNA helix → wrapped around histones → creates nucleosomes → bundles into chromatin → compacts into chromosome

What removes RNA primers in DNA replication?

Nuclease