biochem 012 DNA and protein synthesis part 2(watson, crick, griffith, chargoff's rule, translation,

In nucleotide excision repair, a nuclease cuts out damaged stretches of DNA. DNA polymerase then replaces the excised DNA and DNA ligase seals this newly synthesized DNA.

DNA polymerase III holoenzyme is the primary enzyme complex involved in prokaryotic DNAreplication.

Eukaryotic chromosomal DNA molecules have at their ends nucleotidesequences called telomeres

telomerase

In a bacterium, the DNA is “supercoiled” and found in a region of the cellcalled the nucleoid

Chromatin is a complex of DNA and protein, and is found in the nucleus ofeukaryotic cells

Histones are proteins that are responsible for the first level of DNA packingin chromatin

• • DNA winds around histones to form nucleosome “beads”
• • Nucleosomes are strung together like beads on a string by linker DNA

• Interactions between nucleosomes cause the thin fiber to coil or foldinto this thicker fiber

The 30-nm fiber forms looped domains that attach to proteins

• Loosely packed chromatin is called euchromatin

• During interphase a few regions of chromatin (centromeres and telomeres)are highly condensed into heterochromatin

• The looped domains of the 300 nm fiber coil further

true