The Science Script

  "RNA Interference (RNAi): The Power of Small RNAs in Gene Regulation" Introduction For decades, scientists believed RNA’s main role was to serve as a messenger between DNA and proteins. However, the discovery of RNA interference (RNAi) in the late 1990s transformed molecular biology. RNAi showed that small RNAs can silence specific genes , making them powerful regulators of gene expression. Two of the most studied small RNAs are: Small interfering RNAs (siRNAs) MicroRNAs (miRNAs) These molecules play vital roles in cellular regulation, development, immunity, and disease. 1. What Is RNA Interference? RNA interference (RNAi) is a conserved biological process in which small RNAs guide sequence-specific gene silencing . Key features: Works at the post-transcriptional level . Small RNAs base-pair with target mRNAs. Leads to mRNA degradation or translational repression . 2. Mechanism of RNAi Step 1: Double-stranded RNA (dsRNA) detection dsRNA (vi...

  "DNA Damage and Repair Mechanisms: Guardians of Genome Integrity" # Introduction Our DNA is constantly under attack. Every day, each human cell experiences tens of thousands of DNA lesions from sources such as UV radiation, reactive oxygen species, chemical mutagens, and even normal cellular processes like replication errors. If left unrepaired, these damages can lead to mutations, cancer, neurodegeneration, and aging . Thankfully, cells have evolved sophisticated DNA repair pathways that act as guardians of genome integrity. 1. Sources of DNA Damage Endogenous Replication errors Reactive oxygen species (ROS) from metabolism Spontaneous base deamination, depurination Transposon activity Exogenous UV radiation → thymine dimers Ionizing radiation → double-strand breaks Chemical mutagens (alkylating agents, cross-linkers) Environmental toxins, smoking 2. Types of DNA Damage Base modifications  – oxidation, alkylation, deamination Single-strand breaks (SSBs) Double-str...

 "Non-Coding RNAs in Disease and Therapy: Beyond the Central Dogma" Introduction For decades, biology textbooks focused on the central dogma : DNA → RNA → Protein. But today, we know that most of the human genome does not code for proteins . Instead, it produces a diverse set of non-coding RNAs (ncRNAs) that play regulatory, structural, and catalytic roles . These ncRNAs are not “junk” — they are key regulators of health and disease . Misregulation of ncRNAs is linked to cancer, neurodegeneration, metabolic disorders, and more. Excitingly, ncRNAs are also being explored as therapeutic tools . 1. Types of Non-Coding RNAs a) Housekeeping ncRNAs rRNA (ribosomal RNA) – makes up ribosome structure. tRNA (transfer RNA) – brings amino acids during translation. snRNA (small nuclear RNA) – involved in splicing. b) Regulatory ncRNAs miRNA (microRNA) – ~22 nt, repress translation or degrade mRNA. siRNA (small interfering RNA) – guide sequence-specific mRNA d...

"Epitranscriptomics: RNA Modifications and Their Biological Roles" Introduction For decades, DNA modifications (like DNA methylation ) dominated discussions of epigenetics. But now, scientists are uncovering a new regulatory layer: Epitranscriptomics — the study of chemical modifications on RNA . More than 170 different chemical modifications have been identified on RNAs. These modifications fine-tune RNA stability, localization, translation, and interactions , influencing health and disease. The most well-studied is N6-methyladenosine (m6A) , often called the “epigenetic mark on RNA.” 1. Key RNA Modifications a) m6A (N6-Methyladenosine) Most abundant internal mRNA modification. Added by “writers” : METTL3/METTL14 complex. Removed by “erasers” : FTO, ALKBH5. Recognized by “readers” : YTH domain proteins. Functions: regulates splicing, stability, translation efficiency . b) m5C (5-Methylcytosine) Found in tRNA, rRNA, mRNA. Linked to RNA stabilit...

 "CRISPR and RNA Editing Technologies: Rewriting the Code of Life" Introduction For decades, genetic engineering focused on DNA editing . But DNA changes are permanent, often raising ethical and safety concerns. Enter RNA editing technologies , especially CRISPR-based systems , which allow scientists to edit RNA in real-time, reversibly, and with high precision . Unlike DNA editing, RNA editing does not permanently alter the genome. This makes it a safer, flexible, and powerful tool for both research and medicine. 1. From DNA Editing to RNA Editing DNA Editing (CRISPR-Cas9) Cas9 enzyme cuts DNA at specific sites. Permanent genome modification. Used in agriculture, gene therapy, and synthetic biology.                                                                             ...

 " Ribozymes and Catalytic RNAs: RNA as More Than Just a Messenger" # Introduction For a long time, RNA was thought of as just a messenger — a simple intermediate between DNA and protein. But then came a revolutionary discovery: RNA can act like an enzyme . These self-catalyzing RNA molecules are called ribozymes . This idea challenged the central dogma and even gave birth to the RNA World Hypothesis , which suggests that early life may have relied entirely on RNA for both information storage and catalysis . 1. What are Ribozymes? Definition : RNA molecules with catalytic activity, capable of catalyzing chemical reactions without proteins. Discovered in the 1980s by Thomas Cech (self-splicing introns) and Sidney Altman (RNase P). Both won the 1989 Nobel Prize in Chemistry for this breakthrough. 2. Types of Ribozymes a) Small Self-Cleaving Ribozymes Found in viruses, viroids, and some cellular RNAs. Examples: Hammerhead, Hairpin, Hepatitis delta virus (...

 "DNA Damage and Repair Mechanisms: Guardians of the Genome" # Introduction DNA is the blueprint of life, but it is constantly under attack. Every day, each human cell experiences tens of thousands of DNA lesions caused by UV light, radiation, reactive oxygen species, and even errors during replication . If unrepaired, these damages can lead to mutations, cancer, aging, and cell death . Luckily, cells have evolved sophisticated DNA repair systems —molecular guardians that preserve genetic integrity. 1. Sources of DNA Damage Endogenous Sources Replication errors (mismatches, insertions, deletions). Reactive oxygen species (ROS) from metabolism. Spontaneous hydrolysis (base loss, deamination). Exogenous Sources Ultraviolet (UV) radiation → thymine dimers. Ionizing radiation (X-rays, gamma rays) → double-strand breaks. Chemical mutagens → alkylating agents, intercalating compounds. Environmental toxins → cigarette smoke, pollutants. 2. Ty...