Category: Science
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How to Learn Nucleomorphs and Secondary Endosymbiosis: From Engulfed Algae to Three-Chromosome Relic Nuclei and Complex Plastids
Wait, What? Some Cells Contain a Tiny Second Nucleus That Belonged to Another Eukaryotic Cell A standard eukaryotic cell has one nucleus. Some algae contain something stranger. Cryptophytes and chlorarachniophytes contain a tiny genome-bearing structure called a nucleomorph. A nucleomorph is the extremely reduced nucleus of a eukaryotic alga that was engulfed by another eukaryotic…
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How to Learn Glycosomes and Compartmentalised Glycolysis: From Peroxisome-Like Protein Import to Trypanosome ATP Balance and Metabolic Control
Wait, What? Trypanosomes Put Glycolysis Inside an Organelle—and Can Suffer if the Same Enzymes Are in the Wrong Compartment In most familiar eukaryotic cells, glycolysis occurs in the cytosol. Kinetoplastids such as Trypanosoma brucei do something unusual: much of early glycolysis occurs inside specialised peroxisome-related organelles called glycosomes. glucose → glycosomal phosphorylation and triose reactions…
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How to Learn Peroxisomes and Glyoxysomes: From PEX Protein Import to Fatty-Acid Oxidation, Ether Lipids and Plant Seed Metabolism
Wait, What? A Peroxisome Can Import a Fully Folded Protein Through a Membrane—Then Reuse the Same Organelle for Completely Different Metabolic Jobs Most students learn that membrane-bound organelles import unfolded proteins through narrow translocons. Peroxisomes break that expectation. Many peroxisomal proteins fold in the cytosol, bind soluble receptors and are then imported into the organelle.…
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How to Learn the Synaptonemal Complex and Meiotic Recombination: From Homolog Pairing to Crossover Interference and Chromosome Segregation
Wait, What? Meiosis Deliberately Breaks DNA—Then Builds a Protein Zipper Between Matching Chromosomes Most learners first meet meiosis as a sequence of stages. That description hides the most sophisticated part. Before homologous chromosomes segregate, the cell deliberately creates DNA double-strand breaks. Those breaks help homologs find one another and exchange DNA. At the same time,…
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How to Learn Archaeal ESCRT-III Cell Division: From Cdv Rings to Membrane Constriction, Proteasomal Timing and the Evolution of Cytokinesis
Wait, What? Some Archaea Divide With Machinery Related to the System Human Cells Use to Pinch Membranes Apart Most introductory microbiology teaches bacterial division using FtsZ. But many archaea—especially Sulfolobales—use a very different system. They use proteins related to ESCRT-III, the membrane-remodelling machinery used by eukaryotic cells in membrane abscission, endosomal sorting and membrane repair.…
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How to Learn Plasmodesmata and Symplastic Transport: From Cell-Wall Pores to Callose Gating, Mobile Signals and Plant-Wide Communication
Wait, What? Plant Cells Have Walls Between Them—But Their Cytoplasms Are Still Directly Connected A plant cell wall looks like a barrier. Yet plant tissues are not simply boxes sealed away from one another. Tiny channels cross many cell walls. These channels are plasmodesmata. A plasmodesma creates membrane continuity between neighbouring cells and can allow…
