Define nucleus

Recent Examples on the Web There’s been a kind of nucleus, which people think of as New England, and maybe the West Coast. — How To Save A Country, The New Republic, 11 May 2023 Mendis speculated that the comet’s dark crust was composed of some form of hydrocarbon, was perhaps five-inches thick and was cracked with long crevices that travel halfway around the nucleus. — San Diego Union-Tribune, 3 Feb. 2023 Comets consist of icy volatiles, such as water and carbon dioxide ice, around a nucleus of rocky material pulled from the protoplanetary disc that formed the planets billions of years ago. — Jon Kelvey, Popular Science, 30 Jan. 2023 The Bulls are on a downturn and could decide to make major moves with their nucleus. — Gary Washburn, BostonGlobe.com, 14 Jan. 2023 In contrast to the DNA from the cell nucleus, the mitochondrial genome is small. — Daniela Mocker, Scientific American, 4 Oct. 2022 Nuclear fusion is typically conducted on lighter elements that have lower atomic numbers (the number of protons in the nucleus), while nuclear fission is conducted on heavier elements with much higher atomic numbers. — Caroline Delbert, Popular Mechanics, 11 Aug. 2022 Arhaus provided custom upholstery for the furniture; the oven from JennAir was an essential part of the kitchen area, which serves as the club’s social nucleus. — ELLE Decor, 9 May 2023 The second is defined by a process that occurs in the nucleus of a cesium-155 atom—a process that atomic clocks can calculate with stun...

Suppose that you have a very precious piece of information. Let’s imagine that this piece of information is a blueprint. In fact, it’s not just a blueprint for a house, or a car, or even a top-secret fighter jet. It’s a blueprint for an entire organism – you – and it not only specifies how to put you together, but also provides the information that enables every cell in your body to keep functioning from moment to moment. Sounds important, right? You’d probably want to keep information this valuable in a secure spot, perhaps in a protected vault where you can keep an eye on it. In fact, that’s exactly what eukaryotic cells do with their genetic material, placing it in a membrane-enclosed repository called the nucleus. Eukaryotic DNA never leaves the nucleus; instead, it’s transcribed (copied) into RNA molecules, which may then travel out of the nucleus. In the cytosol, some RNAs associate with structures called ribosomes, where they direct synthesis of proteins. (Other RNAs play functional roles in the cell, serving as structural components of the ribosome or regulating activity of genes.) Here, we’ll look in a little more detail at the structure of the nucleus and ribosomes. The nucleus (plural, nuclei) houses the cell’s genetic material, or DNA, and is also the site of synthesis for ribosomes, the cellular machines that assemble proteins. Inside the nucleus, chromatin (DNA wrapped around proteins, described further below) is stored in a gel-like substance called nucleopl...

The nucleus is a pivotal organelle responsible for regulating almost all forms of cellular activities. Mostly, every type of cell that exists is categorized on the basis of the absence or presence of the nucleus within its cell (categorized either as a prokaryotic or eukaryotic cell.) Table of Contents • • • • Structure Of Nucleus • Typically, it is the most evident organelle in the cell. • The nucleus is completely bound by membranes. • It is engirdled by a structure referred to as the nuclear envelope. • The membrane distinguishes the cytoplasm from the contents of the nucleus • The cell’s chromosomes are also confined within it. • DNA is present in the Chromosomes, and they provide the genetic information required for the creation of different cell components in addition to the reproduction of life. Also Read:Â Nucleus Function Following are the important nucleus function: • It contains the cell’s hereditary information and controls the cell’s growth and reproduction. • The nucleus has been clearly explained as a membrane-bound structure that comprises the genetic material of a cell. • It is not just a storage compartment for DNA, but also happens to be the home of some important cellular processes. • First and foremost, it is possible to duplicate one’s DNA in the nucleus. This process has been named DNA Replication and produces an identical copy of the DNA. • Producing two identical copies of the body or host is the first step in cell division, where every new cell wi...

paraventricular nucleus ( nucleus paraventricula´ris) a band of cells in the wall of the third ventricle in the supraoptic part of the hypothalamus; many of its cells are neurosecretory in function and project to the neurohypophysis, where they secrete oxytocin (and, to a lesser extent, antidiuretic hormone). supraoptic nucleus ( nucleus supraop´ticus) one just above the lateral part of the optic chiasm; many of its cells are neurosecretory in function and project to the neurohypophysis, where they secrete antidiuretic hormone (ADH) and, to a lesser extent, oxytocin; other cells are osmoreceptors that stimulate ADH release in response to increased osmotic pressure. vestibular nuclei, nu´clei vestibula´res the four cellular masses in the floor of the fourth ventricle: superior (rostral or cranial), lateral, medial, and inferior (caudal) vestibular nuclei; in them are the terminations of the branches of the vestibular nerve (see anatomic Table of Nerves in the Appendices). The nuclei give rise to a widely dispersed special sensory system through projections to motor nuclei in the brain stem and cervical cord, to the cerebellum, and to motor cells throughout the spinal cord; they also have connections that provide for conscious perception of, and autonomic reactions to, labyrinthine stimulation. The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. nucleus Histology The organel...

Definition A prokaryotic cell is a type of cell that does not have a true nucleus or membrane-bound organelles. Organisms within the domains Bacteria and Archaea are based on the prokaryotic cell, while all other forms of life are eukaryotic. However, organisms with prokaryotic cells are very abundant and make up much of Earth’s biomass. Overview Organisms that have prokaryotic cells are unicellular. They are called “prokaryotes.” The prokaryotic cell has several elements that allow it to function as a living organism. First, prokaryotes are covered in a cell membrane. This membrane allows them to create a specific environment within the cytosol that allows biochemical reactions to take place. Second, these cells house both loose DNA and ribosomes. Though ribosomes are organelles, they are not bound by a plasma membrane. Together, the DNA and ribosomes work to produce the proteins that the cells need to gather nutrients, reproduce, and even defend themselves in the face of predators or environmental changes! Prokaryotic are much smaller than the smallest eukaryotic cells. In general, a prokaryotic cell is smaller because it has less DNA to create the proteins needed to make an ultra-efficient membrane. So, the cells reach a size where they can no longer import the number of nutrients they need for the volume of cytosol they contain. This is known as a surface-area-to-volume ratio limit. However, bacteria are much larger than viruses because they are actively carrying out t...

Cells are all around us, they make up all living things, from that bacteria that made you sick last week to the tree outside your window, to the cells in your own body. Cells have something called organelles inside them that are specialized structures responsible for different tasks within the cell. For example, the cell membrane protects and surrounds the cell while the mitochondria are responsible for making energy for the cell. If you compare a cell to the human body, the nucleus would be considered the brain of the cell. This is because the nucleus is responsible for everything that goes on in the cell. Just as the brain tells your different body parts what to do, the nucleus tells the organelles what to do! Even further, the nucleus houses the cell's genetic information called deoxyribonucleic acid (DNA). As we already know, the nucleus houses DNA. It surrounds the DNA with a protective membrane called the nuclear envelope, similar in structure to the cell membrane that protects the entire cell. The nuclear envelope provides another layer of protection for the DNA and has small holes in it called pores. There are two main types of cells: prokaryotes and eukaryotes. Prokaryotes are simple cells that make up most single-celled organisms like the bacteria that make you sick. Eukaryotes are larger, more complex cells that make up multi-celled organisms like humans and plants. The main difference between the two types of cells is that eukaryotes have a nucleus and other me...

The atomic nucleus is the central part of an atom. The atomic nucleus also contains all of its positive electric charge (in protons), while all of its negative charge is distributed in the electron cloud. The atomic nucleus was discovered by Ernest Rutherford, who proposed a new model of the atom. Periodic Table Atomic Nucleus A figurative depiction of the helium-4 atom with the electron cloud in shades of gray. Protons and neutrons are most likely found in exactly the same space, at the central point. Source wikipedia.org License CC BY-SA 3.0 In physics, the atomic nucleus is the central part of an atom. In comparison to an atom, it is much more smaller and contains most of the mass of the atom. The atomic nucleus also contains all of its positive electric charge (in protons), while all of its negative charge is distributed in the electron cloud. The atomic nucleus was discovered by Ernest Rutherford, who proposed a new model of the atom based on Geiger-Marsden experiments. These experiments were performed between 1908 and 1913 by Hans Geiger and Ernest Marsden under the direction of Ernest Rutherford. These experiments were a landmark series of experiments by which scientists discovered that every atom contains a nucleus (whose diameter is of the order 10 -14m) where all of its positive charge and most of its mass are concentrated in a small region called an atomic nucleus. In Rutherford’s atom, the diameter of its sphere (about 10 -10 m) of influence is determined by it...