What occurs to DNA at interphase?
DNA is compacted 1000 fold as it is wrapped around the core histone octamer and is arranged in loop domains(scaffolded) and DNA is duplicated
what the main target of interphase and what are 3 phases of interphase
the cell is synthesizing material for cell division
1. G1-Gap phase (growth)
2. S- DNA replication
3.G2- gap phase (growth)
what happens specifically at interphase S?
DNA Replication and the new sister chromatids are held to each other by cohesins(protein
where are sister chromatids later connected at ?
the centromere
What is chromatin like at S phase and why
it is a mix of euchromatin and heterochromatin and is relaxed to allow for access of transcription
what forms heterochromatin and what is it?
phase separation forms heterochromatin by excluding molecules outside it periphery and crowding a group of molecules that allows for compacting
what 2 dimers make up the centromeric (centromere) nucleosomes “ hemisome” OR CENP-A?
- heterodimer (H2A-H2B)
2.heterodimer(CENH3-H4)
what defines where the centromere is
CENP-A which is a variant of H3 which is a looser structure
what is the biggest difference between the histone core octamer dimers and the hemisome dimers
the hemisome doesn’t have an H1 Linker
what are the 4 phases of mitosis ?
- Prophase
2.Prometaphase - Metaphase
- Anaphase
what is condensin?
an ATPase protein that compacts DNA further during Prophase
what are the 3 steps of prophase ?
- Further DNA compaction
- Nuclear envelope breaks down
- Spindles organize
what happens in prometaphase ?
Microtubules connect to the chromatid at the centromere via the kinetochore
what happens in metaphase?
the sister chromatids line up at the metaphase plate
what is cohesin?
it is a protein the holds together sister chromotids
what 2 steps occur at Anaphase?
- Separation of sister chromatids due to enzyme protease cleaving cohesin
- pulling apart of sister to poles that is facilitated by depolarization of kinetochore tubes
what is the kinetochore
made up of 100 proteins its connects microtubules to sister chromatids
what is required for proper localization of the kinetochore?
CENP-A (CEN-H3)
where is cohesin used ?
interphase and anaphase
