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Introduction to Cells, DNA, and Viruses
Published in Patricia G. Melloy, Viruses and Society, 2023
Cellular macromolecules are organized into compartments called organelles (like little organs) that have an organization allowing for the work of the cell to happen. So, like organs such as the heart and lungs that have a special role in the body, organelles have a special role inside the cell. Some examples of key cellular organelles include the nucleus (where DNA is housed), mitochondria (energy generation), and ribosomes (protein production). Except for the nucleolus residing in the nucleus, organelles are found in what is known as the cytoplasm or cytosol of the eukaryotic cell. The nucleus is an important organelle because it acts as the central control point for all the activities of the cell. The nucleus houses most of the cell’s DNA in the form of protein/DNA structures known as chromosomes that allow for condensation of the large amount of genetic material in each cell (Alberts et al. 2019). Cell division occurs in a process known as mitosis, in which the chromosomes are copied and separated equally between the two daughter cells. Later, we will talk about organelles that help move or traffic things around the cell, as well as into and out of the cell. Trafficking-related organelles include the endoplasmic reticulum, Golgi apparatus, and vesicles. Viruses can exploit the cellular trafficking network to move into and out of the cell.
Cancer Biology and Genetics for Non-Biologists
Published in Trevor F. Cox, Medical Statistics for Cancer Studies, 2022
All living things are made up of cells, from the simple unicellular amoeba to the complex human composed of about 37 trillion () cells. Cells that contain a nucleus are called eukaryotic cells; cells without a nucleus are called prokaryotic cells. Bacteria are examples of prokaryotic cells. Humans are eukaryotes consisting of eukaryotic cells, such as bone, nerve and stem cells. In fact, there are about 200 types of cells in our bodies. Figure 2.1 shows a typical eukaryotic cell, illustrating its structure. Cells come in different shapes and sizes; neurons in the brain and nervous system are long and thin, blood cells are roughly spherical, some bone cells are cuboidal and columnar while others have many branches. The size of a red blood cell is , the size of a skin cell is , an ovum , whilst the length of some nerve cells can be over .
Fungi and Water
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Fungi including mushrooms, molds, and yeasts are eukaryotic organisms as vegetable or animal species, but are classified as a separate kingdom because fungal cell walls contain rigid chitin and glucans that are not found in animal, vegetal, or bacterial species (1–8). Eukaryotic cells are cells that contain a nucleus and other organelles enclosed within membranes. In other words, the fungal kingdom comprises a hyper diverse clade of heterotrophic eukaryotes characterized by the presence of a chitinous cell wall, the loss of phagotrophic capabilities, and cell organizations that range from completely unicellular monopolar organisms to highly complex syncytial filaments (containing several nuclei) that may form macroscopic structures (8). Mushrooms like morels, button mushroom, and puffballs are macroscopic multicellular fungi, while molds are a large group of microscopic multicellular fungi. Molds are characterized by filamentous forms named hyphae. Many fungi occur not as hyphae but as unicellular forms called yeasts, which are invisible to the naked eye and reproduce by budding (2–4).
Exploiting active nuclear import for efficient delivery of Auger electron emitters into the cell nucleus
Published in International Journal of Radiation Biology, 2023
Andrey A. Rosenkranz, Tatiana A. Slastnikova, Mikhail O. Durymanov, Georgii P. Georgiev, Alexander S. Sobolev
For most of the cellular life, the contents of the cell nucleus are separated from the cytoplasm by the nuclear envelope, which consists of two phospholipidic membranes and intermembrane space that are permeated by numerous NPC (Lin and Hoelz 2019). NPCs are supramolecular protein structures that form rounded holes in the nuclear envelope where both nuclear membranes are fused. NPCs are embedded within these holes and form a stable protein scaffold. On the nuclear side, the scaffold forms eight extended fibers that are connected in a distal ring and form the nuclear basket. Another eight flexible fibers extend into the cytoplasm. Additional fiber-like extensions in a central opening generate the permeability barrier, which controls the import and export of macromolecules (Knockenhauer and Schwartz 2016). The main components of the eukaryotic NPC, called nucleoporins, are a family of approximately 30 proteins that form a part of the scaffolding and transport functions of NPC. The outer diameter, inner diameter of the central transport channel, height, and molecular mass of the human NPC is approximately 120 nm, 42.5 nm, 80 nm, and 110 MDa, respectively (Lin and Hoelz 2019).
Response characteristics and optimization of electroporation: simulation based on finite element method
Published in Electromagnetic Biology and Medicine, 2021
Cheng Zhou, Zeyao Yan, Kefu Liu
The simulation to analyze the electroporation process in this study was based on the finite element method with COMSOL multi-physics modeling software (ver 5.3). In order to determine the dependence of the electric pulses on intracellular structures, the model in this study featured a spherical cell with two shells, a cell membrane and a nuclear membrane, respectively. We considered the nucleus as a prominent organelle with a double-bilayer membrane envelope. It plays a major role in cellular activities and can be seen under the light microscope. Other organelles such as the mitochondria and the endoplasmic reticulum were omitted from consideration. A 2-D cell model with radius
Selinexor for the treatment of multiple myeloma
Published in Expert Opinion on Pharmacotherapy, 2020
Klaus Podar, Jatin Shah, Ajai Chari, Paul G Richardson, Sundar Jagannath
The nucleus is an organelle, which encapsulates the genetic material with a double membrane, the nuclear envelope, thereby separating transcription in the nucleus from the translational machinery in the cytoplasm. To allow adequate cell function this spatial compartmentalization in eukaryotic cells requires a finely tuned, selective and efficient bidirectional nuclear-cytoplasmic transport of specific proteins and mRNAs through the nuclear pore complex (NPC) of the nuclear envelope. The passage of macro-molecules (>40 kDa), cargo, through the NPC requires specific transport receptor proteins. The mammalian family of karyopherins, representing the main group of transport receptor proteins, consists of 20 members including karyopherin alpha (KPNA) 1–6, karyopherin beta (KPNB) 1, and exportin-1 (XPO-1), also termed chromosome region maintenance – 1 (CRM-1). Dependent on the presence of precise transport signs in cargo proteins, nuclear localization signals (NLS) or nuclear export signals (NES), karyopherins chaperone them into (importins) or out (exportins) of the nucleus using energy from the RanGTPase complex.