The nuclear envelope (also known as the perinuclear envelope, nuclear membrane, nucleolemma or karyotheca) is the double membrane of the nucleus that encloses genetic material in eukaryotic cells. It separates the contents of the nucleus (DNA in particular) from the cytosol(cytoplasm). Image File history File links Diagram_human_cell_nucleus. ... Image File history File links Diagram_human_cell_nucleus. ... The endomembrane system is the system of internal membranes within eukaryotic cells that divide the cell into functional and structural compartments, or organelles. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... The cytosol (cf. ...

Numerous nuclear pores are present on the nuclear envelope to facilitate and regulate the exchange of materials (for example, proteins and RNA) between the nucleus and the cytoplasm. Nuclear pore. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Left: An RNA strand, with its nitrogenous bases. ...

The space between the two membranes that make up the nuclear envelope is called the perinuclear space (also called the perinuclear cisterna), and is usually about 20 - 40 nm wide. Each of the two membranes is composed of a lipid bilayer. The outer membrane is continuous with the rough endoplasmic reticulum. This fluid lipid bilayer cross section is made up entirely of phosphatidylcholine. ... The endoplasmic reticulum or ER (endoplasmic means within the cytoplasm, reticulum means little net) is an organelle found in all eukaryotic cells. ...

The inner membrane is erected upon the nuclear lamina, a network of intermediate filaments made of lamin, that plays a role in mitosis and meiosis. The type of Lamins present are A, B1, B2, and C. The nuclear lamina is the dense, fibrillar network composed of intermediate filaments made of lamin that lines the inner surface of the nuclear envelope. ... // Intermediate filaments (IFs) are important structural proteins which are located both in the cytoplasm and the nucleus. ... A lamin is a fibrous protein that gives the cell nucleus its shape. ... Mitosis divides genetic information during cell division. ... For the figure of speech, see meiosis (figure of speech). ...

The nuclear envelope may also play a role in the disposition of chromatin inside the nucleus. The lamina acts as a site of attachment for chromosomes.It also acts like a shield for the nucleus. Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ...

Disintegration during mitosis in metazoans

During prophase in mitosis, the chromatids begin condensing to form chromosomes, and the nuclear envelope begins to disintegrate. During metaphase, the nuclear envelope is completely disintegrated, and the chromosomes can be pulled apart as chromatids by the spindle fibers. Other eukaryotes such as yeast undergo closed mitosis, where the chromosomes segregate within the nuclear envelope, which then buds as the two daughter cells divide. Newt lung cell in Prophase, with the mitotic spindles stained green and the cell nucleus and chromatin stained blue. ... Mitosis divides genetic information during cell division. ... A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. ... A scheme of a condensed (metaphase) chromosome. ... An image of a newt lung cell stained with fluorescent dyes during metaphase. ... In biology, spindle fibres are microtubules that are responsible for processes such as mitosis and meiosis. ...

External links

• Histology at BU 20102loa
• Animations of nuclear pores and transport through the nuclear envelope
• Illustrations of nuclear pores and transport through the nuclear envelope
• MeSH Nuclear+envelope