Bob Moss: Lead Editor

All Articles Within Nucleic Acid Structure and Function (36)

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DNA Replication (6)

• DNA Replication and Causes of Mutation
  Cells employ an arsenal of editing mechanisms to correct mistakes made during DNA replication. How do they work, and what happens when these systems fail?
• Major Molecular Events of DNA Replication
  Arthur Kornberg compared DNA to a tape recording of instructions that can be copied over and over. How do cells make these near-perfect copies, and does the process ever vary?
• Semi-Conservative DNA Replication: Meselson and Stahl
  Watson and Crick's discovery of DNA structure in 1953 revealed a possible mechanism for DNA replication. So why didn't Meselson and Stahl finally explain this mechanism until 1958?
• Genetic Mutation
  A single base change can create a devastating genetic disorder or a beneficial adaptation, or it might have no effect. How do mutations happen, and how do they influence the future of a species?
• DNA Damage & Repair: Mechanisms for Maintaining DNA Integrity
  DNA integrity is always under attack from environmental agents like skin cancer-causing UV rays. How do DNA repair mechanisms detect and repair damaged DNA, and what happens when they fail?
• Genetic Mutation
  Is it possible to have “too many” mutations? What about “too few”? While mutations are necessary for evolution, they can damage existing adaptations as well.

Transcription & Translation (4)

• Translation: DNA to mRNA to Protein
  How does the cell convert DNA into working proteins? The process of translation can be seen as the decoding of instructions for making proteins, involving mRNA in transcription as well as tRNA.
• DNA Transcription
  If DNA is a book, then how is it read? Learn more about the DNA transcription process, where DNA is converted to RNA, a more portable set of instructions for the cell.
• RNA Transcription by RNA Polymerase: Prokaryotes vs Eukaryotes
  Gene expression is linked to RNA transcription, which cannot happen without RNA polymerase. However, this is where the similarities between prokaryote and eukaryote expression end.
• What is a Gene? Colinearity and Transcription Units
  In 1958, Francis Crick’s sequence hypothesis finally provided an answer to the question: what is a gene? Why is this definition now considered overly simplistic?

Discovery of Genetic Material (4)

• Isolating Hereditary Material: Frederick Griffith, Oswald Avery, Alfred Hershey, and Martha Chase
  How did scientists determine that DNA is the hereditary material? Groundbreaking experiments by Griffith, Avery, Hershey, and Chase disproved the notion that proteins were genetic material.
• Discovery of DNA as the Hereditary Material using Streptococcus pneumoniae
  It was a pleasant surprise to the scientific community when clinical research with the bacterium Streptococcus pneumoniae led to the discovery of DNA as the hereditary material.
• Discovery of DNA Structure and Function: Watson and Crick
  The landmark ideas of Watson and Crick relied heavily on the work of other scientists. What did the duo actually discover?
• Barbara McClintock and the Discovery of Jumping Genes (Transposons)
  McClintock’s maize breeding experiments provided the first detailed descriptions of transposable elements. What exactly are these “jumping genes”, and why are they so important?

RNA (8)

• RNA Functions
  The central dogma of molecular biology suggests that the primary role of RNA is to convert the information stored in DNA into proteins. In reality, there is much more to the RNA story.
• RNA Transcription by RNA Polymerase: Prokaryotes vs Eukaryotes
  Gene expression is linked to RNA transcription, which cannot happen without RNA polymerase. However, this is where the similarities between prokaryote and eukaryote expression end.
• Chemical Structure of RNA
  The more researchers examine RNA, the more surprises they continue to uncover. What have we learned about RNA structure and function so far?
• RNA Splicing: Introns, Exons and Spliceosome
  What's the difference between mRNA and pre-mRNA? It's all about splicing of introns. See how one RNA sequence can exist in nearly 40,000 different forms.
• What is a Gene? Colinearity and Transcription Units
  In 1958, Francis Crick’s sequence hypothesis finally provided an answer to the question: what is a gene? Why is this definition now considered overly simplistic?
• Restriction Enzymes
  Restriction enzymes are one of the most important tools in the recombinant DNA technology toolbox. But how were these enzymes discovered? And what makes them so useful?
• Genome Packaging in Prokaryotes: the Circular Chromosome of E. coli
  How do bacteria, lacking a nucleus, organize and pack their genome into the cell? Supercoiling enables this but forces a different kind of transcription and translation in prokaryotes.
• Eukaryotic Genome Complexity
  How many genes are there? This question is surprisingly not very important, and has nothing to do with the organism’s complexity. There is more to genomes than protein-coding genes alone.

Gene Copies (5)

• Copy Number Variation and Genetic Disease
  Did you know that a large number of your genes exist in variable numbers of copies? While they can overlap with disease-related genes, these variants exist in healthy individuals too.
• DNA Deletion and Duplication and the Associated Genetic Disorders
  Deletions and duplications of single-base pairs typically arise during homologous recombination and cause diseases. But what happens when a mutation occurs over multiple genes?
• Tandem Repeats and Morphological Variation
  All mammals have basically the same set of genes, yet there are obviously some significant differences that distinguish the various species. Recent research suggests that one such difference involves tandem repeats, or short lengths of DNA that are repeated multiple times within a gene. But what, if anything, does having a different number of tandem repeats do to an organism?
• Copy Number Variation
  Copy number variations (CNVs) have been linked to dozens of human diseases, but can they also represent the genetic variation that was so essential to our evolution?
• Copy Number Variation and Human Disease
  Analysis of individual human genomes has revealed an unexpected amount of variability in human populations. Copy number variation (CNV) has recently been identified as a major cause of structural variation in the genome, involving both duplications and deletions of sequences that typically range in length from 1,000 base pairs to 5 megabases, the cytogenetic level of resolution. Evidence is accumulating that CNVs play important roles in human disease.

Jumping Genes (4)

• Transposons: The Jumping Genes
  Transposable elements, or "jumping genes", were first identified by Barbara McClintock more than 50 years ago. Why are transposons so common in eukaryotes, and exactly what do they do?
• Barbara McClintock and the Discovery of Jumping Genes (Transposons)
  McClintock’s maize breeding experiments provided the first detailed descriptions of transposable elements. What exactly are these “jumping genes”, and why are they so important?
• Transposons, or Jumping Genes: Not Junk DNA?
  For decades, scientists dismissed transposable elements, also known as transposons or “jumping genes”, as useless “junk DNA”. But are they really?
• Functions and Utility of Alu Jumping Genes
  Alu elements have long been considered “junk” DNA--or, even worse, “selfish” DNA. Turns out, these prolific transposons are much more useful than originally thought.

Applications in Biotechnology (4)

• Recombinant DNA Technology and Transgenic Animals
  GloFish are the first transgenic animals available to the American public. But what's the biotechnology behind them?
• Genetically Modified Organisms (GMOs): Transgenic Crops and Recombinant DNA Technology
  If you could save lives by producing vaccines in transgenic bananas, would you? In the debate over large-scale commercialization and use of GMOs, where should we draw the line?
• The Biotechnology Revolution: PCR and the Use of Reverse Transcriptase to Clone Expressed Genes
  Gene cloning and PCR allow scientists to make a large amount of DNA from only a small fragment. How do these technologies work?
• Antibiotic Resistance, Mutation Rates and MRSA
  In bacteria, mutations in plasmids can accumulate surprisingly fast. What does this mean for us humans, who have to fight with these new antibiotic resistant strains?