Essentials of the nucleus in the eukaryotic cell
This Blog Discusses, Phospholipid Bilayer Membrane of the Nucleus, Nucleolus of the Nucleus, Chromatin in the Nucleus, Cellular and Atomic Nucleus.
Following Block diagram will provide you a roadmap that can make your work simple to understand the Nucleus.
Welcome to the Biologia park once again. Previously we have taken a quite heavy dose of biomolecules, their role, effect, and different types of biomolecules present in the living and non-living matter. Today we will deal with the most important organelle of the cellular body that is NUCLEUS. It is the largest organelle present in the eukaryotic body. It acquires a large portion of the total cell volume. As we know nucleus is the structure by which all the cellular activities are get controlled; hence we can name it as a controller of the cell.
The nucleus is initially recognized as a cell organelle by Scottish botanist Robert Brown. And the material present in the nucleus is visualized using simple dye (a coloring agent) by the German biologist and founder of cytology called cell biology Walther Flemming; that material is further recognized as a genetic material known as chromatin.
Space that produces a barrier between the internal material of the nucleus and the external cytoplasm is known as perinuclear space, which is 10-50 nm. When a nucleus is in its INTERPHASE stage, the non-dividing phase possesses a highly elaborated and extended form of chromatin. The nucleus is mainly composed of four parts, viz.
Phospholipid Bilayer Membrane of Nucleus
The double layer of the nucleus, known as the nuclear membrane, is the composition of lipid molecules and a phosphate group that forms a phospholipid. It forms two parallel layers, which are separated by periplasmic space. These phospholipids form lipid bilayer Nucleus envelope. The outer layer of the membrane is covered with small interruptions known as Nuclear Pore.
Nuclear pores are made up of proteins. These pores are the medium through which protein and RNA transport from the nucleus to the cytoplasm and cytoplasm to the nucleus. The nuclear pore and nuclear membrane are separated by perinuclear cisterna. The periplasmic space separates the inner and outer layers. The outer layer is extended in association with the endoplasmic reticulum, which bears ribosomes on it.
The endoplasmic reticulum with ribosomes is called the rough endoplasmic reticulum (RER). The endoplasmic reticulum without ribosomes is known as the smooth endoplasmic reticulum (SER). For example, cactus with spines and without spines. Ribosomes are the site for protein synthesis.
The fibrous lamina is part of the nuclear cytoskeleton and attached to the inner layer of the nuclear membrane. It consists of the fine filament of protein which provides mechanical reinforcement to the lipid bilayer membrane.
This filamentous protein regulated the gene expression, entry, and exit of various substances. It provided an anchor site for the pore complex.
Nucleoplasm
Nucleoplasm is the combination of Nucleolus and Chromatin. It is the remaining part, excluding the nucleolus. It is also known as nuclear sap, which contains many dissolved salts, enzymes, and many organic compounds. It provides protection to the nucleolus and chromatin. It maintains the shape of the nucleus, which depends on the number of processes occurring in the nucleus and the number of nucleoli present.
Nucleolus
It is one or more dense granular spherical body that is the site for RNA and protein synthesis. The nucleus is the most prominent part of the cell-like the nucleolus is the most prominent part of the nucleus. All active ribosomal RNA (rRNA) is synthesis in the nucleolus. It is the non-membrane-bound structure that lacks its own membrane. A large number of nucleolus (singular- nucleoli) presence favors more and active protein synthesis.
Breaking and reforming property of the nucleolus can be seen during the cell division process means during cell division, it breaks step by step and again reforms throughout various phases of cell division. The size of nucleoplasm depends on the level of ribosome production, and different molecular processes occur in it. The nucleolus provides the site for the transcription and ribosomal gene processing, helpful in the growth and development of the cell.
Chromatin in the nucleus
It is a thread-like structure present in the nucleus, seen only when the cell is in the non-dividing stage. It is a part of a chromosome that is visible only in a dividing cell. It consists of DNA (deoxyribonucleic acid) and Protein. DNA is the ladder full of genetic instructions. Single human cell possesses 2m long thread of DNA, which is distributed in forty-six (46) chromosomes that are twenty-three (23) pairs of chromosomes. Chromatin is surrounded with the histone protein, which is alkaline, and some non-histone proteins also. In the initial stages, each chromosome contains a primary constrict or centromere. Centromere has a disc-shaped structure called kinetochores on its side.
The centromere holds two chromatids of the chromosome; you can imagine the structure-like sign of multiplication. The classification of the centromere is based on its location on the chromosome. It can present in the middle, end, near the end, and away from the middle of the chromosome.
The metacentric centromere present in the middle and forms two equal arms of the chromosome. Submetacentric in which centromere is present slightly away from the middle, and it forms one short and one long arm. Telocentric is when the centromere is present at the terminal end and acrocentric. The centromere is present near the end, which results in the formation of one extremely short and one extremely long arm.
Cellular and Atomic nucleus
The nucleus maintains the integrity of the cell by providing a site for the various processes, for example, transcription and replication, which are required for the growth, development, and repair mechanism of the cell. It is a membrane-bound structure present only in eukaryotic cells known as a cellular nucleus that contains genetic material that is DNA. It works as a command center for the complete cell.
Generally, the nucleus imagines as a spherical body, but the shape of the nucleus depends on the type of cell in which it is present; it can be ellipsoid or irregular, flattened in shape. The major key hint will be the presence of a membrane-bound structure that is the nucleus to differentiate between eukaryotic and prokaryotic organisms. Prokaryotic cells lack a nucleus that means there is no membrane-bound organelle present.
The basic difference between atomic and cellular nucleus is, the atomic nucleus is composed of proton and neutron. It is small in size. There is the presence of empty space between electron cloud and nucleus, which is overcome in the cellular nucleus due to nucleoplasm.
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