Lesson 7: Interphase nucleus

Characteristics

Membranous organelle, characteristic of eukaryotic cells, which contains the genetic material and allows the compartmentalization of DNA

Types of chromatin

2 types of chromatin:

• Euchromatin: Dispersed chromatin, grey colour:

active transcription

• Heterochromatin (90%): Condensed chromatin, darker:

silenced genes, no transcription

Types of heterochromatin

Constitute - always inactive

Facultative - can get active

Nuclear envelope

Protein network formed by intermediate filaments inside the nucleus.

Consists of:

Outer/Inner Membrane

Perinuclear space

Nuclear lamina: formation of chromosomes from chromatin and cell division

Nuclear pores: allow transport RNA and proteins

Nucleoplasm/Karyoplasm

Contains nuclear components

Similar to cytosol

Placenta of Replicationa nd transcription

Chromatin

Constituted by DNA, histones and RNA

Chromatin compaction level: First level

Nucelosomes

Not tight

Second level: Chromatin fibre

Very tigh

Nucleolus

Main function: synthesis of rRNA and Asse,Bly of ribosomal subunits

Difference nucleus interphase and mitosis

Interphase: Chromosomes are replicated, chromatin less condensed

Mitosis: chromatin very condensed and chromosomes distributed into 2 daughter cells