Nucleus structure

Flashcards generated from lecture notes on the Nucleus.

Nucleus

The most prominent organelle containing genetic material (DNA) compacted into Chromosomes.

Chromosomes

Compacted form of DNA located within the Nucleus.

Transcription

The process where DNA is copied into RNA inside the Nucleus.

Mitosis

Cell division process requiring segregation of chromosomes in the nucleus.

Meiosis

Special case of cell division requiring segregation of chromosomes in the nucleus.

Nucleoplasm

The interior of the nucleus which communicates with the Cytosol through Nuclear Pores.

Nuclear Pores

Defined points where the Nucleoplasm communicates with the Cytosol.

Perinuclear Space

A structure within the nucleus.

Nuclear Lamina

A structure within the nucleus.

Nucleolus

A structure within the nucleus.

Nuclear Envelope

Double membrane that demarcates the nucleus, typically 5-20 µm in diameter.

Endoplasmic Reticulum

The Perinuclear Space is continuous with the inside of this organelle.

Nuclear Lamina

Mesh of fibres supporting the nuclear envelope composed of intermediate filaments (IFs).

Lamins

Type of intermediate filaments that comprise Nuclear Lamina.

Mitosis

During this process the nuclear lamin network must breakdown, but reform at the end.

Phosphorylation and Dephosphorylation

Controls the assembly and disassembly of Lamin Fibres.

Nuclear Pores

Protein bounded structures through which the nucleoplasm communicates with the cytosol allowing free diffusion of small molecules, but requiring active transport for larger molecules.

Nuclear Localisation Signals (NLS)

Proteins to be imported into the nucleus have these.

Ribonucleoprotein (RNP) Complex

mRNA moves out of the nucleus by association with proteins to form this.

Nuclear Export Signals (NES)

Recognized by the nucleoplasmic side of the nuclear pore allowing mRNA to export out of the nueclus.

Importins

Helps transport NLS (Nuclear Localisation Signals) into the nucleus.

Exportins

Helps transport NES (Nuclear Export Signals) out of the nucleus.

Nucleolus

Round structure present in the Nucleus responsible for the transcription of rRNA.

rRNA

Ribosomal RNA important as a part of the ribosome which translates mRNA into protein.

Pars Fibrosa

A region in the nucleolus - Dense rim of filaments composed of newly synthesised rRNA

Pars Granulosa

A region in the nucleolus - Accumulating particles consisting of the rRNA and protein complex known as ribonucleoprotein complex prior to export.

Histones

Proteins that help compact DNA.

Heterochromatin

Inactive, tightly packed DNA/protein complex also known as a chromosome.

Euchromatin

Active, loosely packed DNA/protein complex also known as a chromosome.

Mitotic Process

Chromosomes become visible to light microscopy during this process.