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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.
The cell and tissues
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
Within the nucleus there is an area called the nucleolus. The nucleolus is primarily responsible for the production of ribosomal RNA (rRNA), which combines with proteins imported from the cytoplasm to make the ribosomes, which then leave the nucleus and enter the cytoplasm to attach to endoplasmic reticulum or to attach to the cytoskeleton as individual units.
Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The plasma cell is usually found in loose connective tissue and in great numbers in lymphatic tissue. It is derived from B-lymphocytes which differentiate in the connective tissue after antigenic stimulation. Antibody production is the function of the plasma cell (see Chapter 5). In routine staining for light microscopy, plasma cells can be seen to contain a large amount of cytoplasm relative to the size of the nucleus. The nuclear chromatin is distributed in clumps around the periphery of the cell. The nucleolus is prominent. The plasma cell can sometimes contain acidophilic granules termed Russel bodies. Ultrastructurally, plasma cells have an abundance of rough endoplasmic reticulum and prominent organelles such as a large Golgi region, mitochondria, polyribosomes, and finger-like extensions of the plasma membrane. The abundance of rough endoplasmic reticulum suggests protein secretion, a finding consist with their role of producing antibodies for release into the blood.204
Ribosomopathies and cancer: pharmacological implications
Published in Expert Review of Clinical Pharmacology, 2022
Gazmend Temaj, Sarmistha Saha, Shpend Dragusha, Valon Ejupi, Brigitta Buttari, Elisabetta Profumo, Lule Beqa, Luciano Saso
Approximately 200–400 copies of rDNA exist in the human genome, and some carry mutations in the sequence of mature mRNA [13]. To date, more than 200 post-transcriptional modifications have been known to occur in the rRNA region and participate in mRNA and tRNA binding [14–17]. These modifications can impact the ribosome structure and influence mRNA [18–20] selectively, thus favoring the expression of a cancer genome [21,22] and several hereditary diseases [23,24]. It has been demonstrated that structural alterations of the nucleolus can impact ribosome biogenesis and are associated with various conditions, including tumors [25]. It has already been known that the increased volume of the nucleolus is associated with different types of tumors [25]. Impairment of ribosome biogenesis is related to the development of different types of tumors [26].
Use of argyrophilic nucleolar–organizer region-associated protein synthesis in skeletal muscle cells for prediction of chronic carbon monoxide exposure
Published in Toxin Reviews, 2020
Harun Gunes, Ayhan Saritas, Recep Eroz, Serdar Colakoglu
AgNORs are functional components of the nucleolus in which actively transcribed rDNA is surrounded by lots of regulatory proteins in the interphase (Ploton et al.1988). Various nucleolar proteins have been described in humans. Most of them are thought to be involved in the processing and maturation of rRNAs, and formation of mature ribosomes. (Scherl et al.2002, Andersen et al.2005, Boisvert et al.2007). Major physiological cellular processes including ribosome assembly, generation of ribonucleoprotein complexes and mitosis (cell proliferation) are connected with the nucleolus (Boisvert et al.2007). Low levels of CO play a crucial role in the regulation of cell proliferation (mitosis), and AgNOR amounts can be used as a proliferation marker (Pich et al.2004, Eroz et al.2011, 2013). Additionally, the number, distribution, and shape of AgNORs provide significant information about the behavior of the cell with respect to the current secretory capacity.
Differentiation of spermatogonial stem cells by soft agar three-dimensional culture system
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Elham Mohammadzadeh, Tooba Mirzapour, Mohammad Reza Nowroozi, Hamid Nazarian, Abbas Piryaei, Fatemeh Alipour, Sayed Mostafa Modarres Mousavi, Marefat Ghaffari Novin
Two groups of cells were identified in the cell suspension based on size and morphology. The first group had a diameter of 8–9 micrometers, with irregular edges and round transparent appearance. These cells were proliferated and formed a layer at the bottom of the plate, which was considered as a feeder layer. The second group of the cells was larger than the first one and had a diameter of 15–17 micrometers and their appearance was spherical and had two or three nucleoli outside the center. These cells were proliferated and several colonies with different numbers and diameters appeared in the culture system, so that the average number of colonies was 13.3 ± 0.7 and the average diameter of colonies was 157.8 ± 16.7. In this study, the presence of FSH receptor as a marker on the surface of Sertoli cells was confirmed by immunocytochemistry method. These cells appeared green color (Figure 1(c,d)).