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Introduction to Cells, DNA, and Viruses
Published in Patricia G. Melloy, Viruses and Society, 2023
Viruses and Society is a college-level textbook geared towards introductory biology students or anyone with an interest in science who wants to understand viruses and their impact on our world. We will begin with an introduction to macromolecules, genes, and cells, followed by viruses that infect cells. Then, in Chapter 2, we will cover how the immune system works and how scientists harness the immune system to enhance immunity through vaccines. Next, we will take up case studies of the 1918 influenza pandemic, the fight to eradicate polio, the HIV/AIDS pandemic, and our current coronavirus COVID-19 crisis. We will also review genetic engineering, in which deoxyribonucleic acid (DNA) can be manipulated to be expressed in other organisms. Viruses are also used in gene therapy, among other ways that humans have used viruses for their own productive purposes. Finally, we will end the book by talking about public health initiatives to keep emerging viruses in check and the role of science communication in how viruses are perceived and have an impact on our society.
The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
Genetic information is stored and transferred in the form of the nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These molecules provide the necessary information for protein production. Like many biological molecules, nucleic acids are multimers of smaller units; which in this case are known as nucleotides. A set of four nucleotide components is used to generate DNA or RNA. Adenine (A), guanine (G) and cytosine (C) are common to both DNA and RNA. Thymine (T) is found in DNA but absent from RNA, with uracil (U) present in its place.
Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Genes are composed of deoxyribonucleic acid (DNA) and are contained on the chromosomes. Each strand of DNA has a specific sequence of four nucleotides, each containing a different base, adenine, thymine, cytosine, or guanine. Adenine pairs with thymine and cytosine pairs with guanine as two complementary strands of DNA are wound together to form a double helix. Genes have a common basic structure (Fig. 20). First, there are upstream sequences that regulate transcription, known as promoters and enhancers. Then, there is a transcription initiation site, followed by a series of alternating exons and introns. The DNA sequence serves as a template from which messenger RNA (mRNA) is made; this process is known as transcription. As transcription proceeds, a primary mRNA is made from the DNA sequence of the gene, which includes the introns. The intron sequences are then spliced out and the exons are linked together to form the mature mRNA molecule. Thus, the exons are the only portions of the gene that specify the final protein product. The mature mRNA molecule is used to make the protein product by the process of translation. Groups of three nucleotides, called codons, code for specific amino acids. Transfer RNA (tRNA) and ribosomal RNA (rRNA) interact with the mRNA to assemble the amino acids into a polypeptide chain to form the final protein molecule.
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
Ribosomes are ribonucleoprotein complexes discovered by Palade and Porter in 1954 as small round bodies associated with the endoplasmic reticulum (ER), as observed using an electronic microscope [1]. It is well known that genetic information is stored in deoxyribonucleic acid (DNA) molecules, and by the highly regulated mechanism of transcription, genes, as particular segments of DNA, are copied into mRNA (ribonucleic acid) by the RNA polymerase enzyme. Ribosome macromolecules catalyze the translation of information from mRNAs into functional polypeptide chains. Ribosomes consist of large and small subunits. Eukaryotic ribosome consists of a smaller 40S subunit and a large 60S subunit. The smaller 40S subunit consists of 18S ribosomal RNA (rRNA) and 33 ribosomal protein small (RPS) subunits, whereas the 60S subunit contains 28S, 5S, and 5.8S rRNA and 47 ribosomal protein large (RPL) [2,3].
Prevalence of SLCO1B1 single nucleotide variations and their association with hypercholesterolaemia in hypercholesterolemic patients in Gauteng, South Africa
Published in Xenobiotica, 2021
Rene de Beer, Kim Outhoff, Alisa Phulukdaree, Prashilla Soma
Pharmacogenetic studies show that single nucleotide variations (SNVs), which are single base-pair mutations at specific sites in the human deoxyribonucleic acid (DNA) sequence, play an important role in the response and outcome of certain therapies (Klug 2012; Kotlęga et al. 2016). Of the numerous SNVs identified, SLCO1B1 rs4149056, rs2306283 and rs4363657 are the strongest contenders for genetic predisposition to statinintolerance ( Khine et al. 2016; Link et al. 2008; Santos et al. 2011; Snpedia.com 2018; Stewart 2013). The most common and well characterized variants of SCLO1B1 are rs2306283 and rs4149056. These two variants appear to be in partial linkage disequilibrium, meaning these variants are more likely to be associated within a population than variants that are unlinked (Holloway and Prescott 2017) and most commonly occur in the four different haplotypes as presented in Table 1.
Preclinical discovery and development of abemaciclib used to treat breast cancer
Published in Expert Opinion on Drug Discovery, 2021
Matthew D. Wright, Jame Abraham
With uncontrolled cell division as a hallmark of cancer, cells commit and arrange for the next round of DNA (deoxyribonucleic acid) (S phase) and cellular replication (M phase) during the G1 phase [7]. Among a family of serine–threonine kinases, CDKs 1–6 are important for coordination of cell-cycle progression. CDKs 7, 8, and 9 act as transcriptional regulators [8]. CDK4, CDK6 (both active kinase heterodimers that are specific for cyclin D), and CDK2 (specific for cyclin E) are three interphase CDKs that consecutively phosphorylate retinoblastoma (Rb) [9]. A tumor suppressor protein, Rb normally inhibits cell proliferation via binding and repressing E2F, a family of transcription factors [10]. Hypophosphorylated Rb confines E2F resulting in reduced expression of genes that promote progression from G1 to S, thus halting cell-cycle progression [11]. To promote cell-cycle progression during G1, the CDK4/6-cyclin D complex induces the phosphorylation at one site on Rb protein. Next, the CDK2-cyclin E complex phosphorylates the remaining 13–14 sites on Rb. Hyperphosphorylated Rb then surrenders the bound E2F [12], which once released directly binds DNA promoting transcription of cyclin E, creating a positive feedback loop and ongoing progression through the cell cycle [13]. After progression from G1 to S phase, cyclin E-CDK2 promotes preparation for DNA synthesis and CDK1 acts to initiate mitosis [8].