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Topic Review
Translation
In molecular biology and genetics, translation is the process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire process is called gene expression. In translation, messenger RNA (mRNA) is decoded in a ribosome, outside the nucleus, to produce a specific amino acid chain, or polypeptide. The polypeptide later folds into an active protein and performs its functions in the cell. The ribosome facilitates decoding by inducing the binding of complementary tRNA anticodon sequences to mRNA codons. The tRNAs carry specific amino acids that are chained together into a polypeptide as the mRNA passes through and is "read" by the ribosome. Translation proceeds in three phases: In prokaryotes (bacteria and archaea), translation occurs in the cytosol, where the large and small subunits of the ribosome bind to the mRNA. In eukaryotes, translation occurs in the cytoplasm or across the membrane of the endoplasmic reticulum in a process called co-translational translocation. In co-translational translocation, the entire ribosome/mRNA complex binds to the outer membrane of the rough endoplasmic reticulum (ER) and the new protein is synthesized and released into the ER; the newly created polypeptide can be stored inside the ER for future vesicle transport and secretion outside the cell, or immediately secreted. Many types of transcribed RNA, such as transfer RNA, ribosomal RNA, and small nuclear RNA, do not undergo translation into proteins. A number of antibiotics act by inhibiting translation. These include anisomycin, cycloheximide, chloramphenicol, tetracycline, streptomycin, erythromycin, and puromycin. Prokaryotic ribosomes have a different structure from that of eukaryotic ribosomes, and thus antibiotics can specifically target bacterial infections without any harm to a eukaryotic host's cells.
  • 1.9K
  • 14 Nov 2022
Topic Review
Nitric Oxide in Stem Cell Biology
Nitric oxide (NO) is a highly reactive gas with a brief life span, synthesized by the enzyme nitric oxide synthase (NOS) through L-arginine oxidation to L-citrulline. The dual role of NO in embryonic stem cells (ESCs) has been previously reported, preserving pluripotency and cell survival or inducing differentiation with a dose-dependent pattern. In this line, high doses of NO have been used in vitro cultures to induce focused differentiation toward different cell lineages being a key molecule in the regenerative medicine field. Moreover, optimal conditions to promote pluripotency in vitro are essential for their use in advanced therapies.
  • 1.8K
  • 15 Apr 2022
Topic Review
Thymoquinone and COVID-19
Thymoquinone (TQ) is the most pharmacologically active ingredient in Nigella sativa seeds (black seeds); it is reported to have anticancer, anti-inflammatory and antioxidant effects in various settings.
  • 1.8K
  • 02 Jun 2021
Topic Review
Weismann Barrier
The Weismann barrier has long been regarded as a basic tenet of biology. However, upon close examination of its historical origins and August Weismann's own writings, questions arise as to whether such a status is warranted. As scientific research has advanced, the persistence of the concept of the barrier has left us with the same dichotomies Weismann contended with over 100 years ago: germ or soma, gene or environment, hard or soft inheritance. 
  • 1.8K
  • 30 Jan 2021
Topic Review
siRNA Structure, Function and Delivery
siRNA is a double-stranded RNA molecule with 21- and 22-nucleotide generated by ribonuclease III cleavage from longer double-stranded RNA (dsRNAs). After binding to the RNA-induced silencing complex (RISC) in the cytoplasm, the sense strand of siRNA undergoes ejection, while the antisense strand of siRNA targets the complementary messenger RNA (mRNA). 
  • 1.8K
  • 20 May 2022
Topic Review
HIV-1 Capsid Protein
The capsid (CA) protein of the human immunodeficiency virus type 1 (HIV-1) is an essential structural component of a virion and facilitates many crucial life cycle steps through interactions with host cell factors. Capsid shields the reverse transcription complex from restriction factors while it enables trafficking to the nucleus by hijacking various adaptor proteins, such as FEZ1 and BICD2. In addition, the capsid facilitates the import and localization of the viral complex in the nucleus through interaction with NUP153, NUP358, TNPO3, and CPSF-6. In the later stages of the HIV-1 life cycle, CA plays an essential role in the maturation step as a constituent of the Gag polyprotein. In the final phase of maturation, Gag is cleaved, and CA is released, allowing for the assembly of CA into a fullerene cone, known as the capsid core. The fullerene cone consists of ~250 CA hexamers and 12 CA pentamers and encloses the viral genome and other essential viral proteins for the next round of infection. As research continues to elucidate the role of CA in the HIV-1 life cycle and the importance of the capsid protein becomes more apparent, CA displays potential as a therapeutic target for the development of HIV-1 inhibitors.
  • 1.7K
  • 20 Feb 2021
Topic Review
SOS Family and Ras-GEFs
The SOS family of Ras-GEFs encompasses two highly homologous and widely expressed members, SOS1 and SOS2. Despite their similar structures and expression patterns, early studies of constitutive KO mice showing that SOS1-KO mutants were embryonic lethal while SOS2-KO mice were viable led to initially viewing SOS1 as the main Ras-GEF linking external stimuli to downstream RAS signaling, while obviating the functional significance of SOS2. Subsequently, different genetic and/or pharmacological ablation tools defined more precisely the functional specificity/redundancy of the SOS1/2 GEFs.
  • 1.7K
  • 05 Jul 2021
Topic Review
The Mitotic Spindle
During cell division, the mitotic spindle, a macromolecular structure primarily comprised of microtubules, drives chromosome alignment and partitioning between daughter cells. Mitotic spindles can sense cellular dimensions in order to adapt their length and mass to cell size.
  • 1.7K
  • 29 Jan 2022
Topic Review
Crosstalk
Biological crosstalk refers to instances in which one or more components of one signal transduction pathway affects another. This can be achieved through a number of ways with the most common form being crosstalk between proteins of signaling cascades. In these signal transduction pathways, there are often shared components that can interact with either pathway. A more complex instance of crosstalk can be observed with transmembrane crosstalk between the extracellular matrix (ECM) and the cytoskeleton.
  • 1.7K
  • 08 Nov 2022
Topic Review
Association between Membrane Proteins and Disease
Cell membranes, including membrane carrier proteins, membrane channel proteins and ATP drive pumps, are the main transporters. Membrane transporters have wide, but specific tissue distributions. They can impact on multiple endogenous and xenobiotic processes. Transport proteins constitute approximately 10% of most proteomes and play vital roles in the translocation of solutes across the membranes of all organisms. The receptor proteins on the cell membrane are also important structures involved in substrate transport and signal communication. The obstacles of cell transport-related proteins directly lead to the lack or excess of certain substances in cells.
  • 1.6K
  • 04 Nov 2021
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