Microscopy Techniques Overview

Microscopy Techniques

• Light microscope: Uses visible light and glass lenses to magnify objects many times.
• Compound light microscope: Uses two lenses—objective and eyepiece—for magnification.
• Differential staining: Using specific stains to distinguish cell types.
• Counterstain: A second stain with a contrasting colour to enhance microscopic viewing.
• Electron microscopy: Uses a beam of electrons instead of light, providing higher resolution images than light microscopes.
• Ultrastructure: Cellular features visible through electron microscopy.
• Artifacts: Structures or objects created during specimen preparation, not actually present within the original sample.
• Transmission electron microscope (TEM): Electrons pass through the specimen to create an image.
• Scanning electron microscope (SEM): Electrons scan the specimen's surface, producing a three-dimensional image.
• Laser scanning confocal microscope: Uses fluorescence and a pin-hole aperture for high-resolution images.

Cell Types and Structures

• Prokaryotic cells: Lack membrane-bound nucleus and organelles.
• Eukaryotic cells: Possess a nucleus and membrane-bound organelles.
• Magnification: Represents how much larger an image appears than the actual object.
• Resolution: Ability to distinguish two separate objects as distinct entities.
• Cytoplasm: Internal fluid containing cytosol (water, salts, organic molecules), cytoskeleton and organelles.
• Metabolism: The sum of all chemical reactions in an organism.
• Organelles: Membrane-bound compartments with specific functions within eukaryotic cells.
• Nucleus: Cell organelle containing DNA and RNA, crucial for cell growth and reproduction.
• Histones: Proteins forming chromatin complexes with DNA.
• Chromatin: Uncondensed DNA combined with histones.
• Chromosomes: Condensed and coiled chromatin structures visible during cell division.
• Mitochondria: Organelles involved in respiration and energy production.
• Cristae: Highly folded inner mitochondrial membranes increasing the surface area for reactions.
• Matrix: Fluid-filled interior of the inner mitochondrial membrane, where reactions occur.
• Mitochondrial DNA: DNA found within the mitochondrial matrix.
• Vesicles: Small membrane sacs involved in transporting materials within and out of the cell.
• Lysosomes: Vesicles containing enzymes for breaking down waste materials.
• Cytoskeleton: Network of protein fibres in the cytoplasm providing structural support and enabling cell movement.
• Microfilaments: Actin protein fibres involved in cell movement and cell division.
• Microtubules: Tubular structures forming a scaffold, aiding organelle transport.
• Intermediate fibres: Fibres providing structural support and maintaining cell integrity.
• Centrioles: Cytoskeletal components involved in cell division.
• Secretion: Process of releasing substances from cells, glands, or organs.
• Endoplasmic reticulum (ER): Network of membranes involved in protein and lipid synthesis.
• Rough ER: ER with ribosomes attached, involved in protein synthesis and transport.
• Smooth ER: ER without ribosomes, involved in lipid and carbohydrate synthesis and storage.
• Ribosomes: Sites for protein synthesis, composed of RNA and proteins.
• Golgi apparatus: Organelle modifying, packaging and transporting proteins.
• Tonoplast: Membrane surrounding the vacuole in plant cells.
• Cell wall: Rigid outer layer found in some cell types, providing support.
• Vacuole: Membrane-bound sac used in transporting or storing materials.
• Chloroplast: Organelle in plant cells responsible for photosynthesis.
• Stroma: Fluid-filled space in chloroplasts surrounding the thylakoid membranes, where reactions occur.
• Granum: Stack of thylakoid membranes within chloroplasts, containing chlorophyll for photosynthesis.
• Endosymbiosis: Theory explaining how eukaryotic cells evolved from prokaryotic cells.

Molecular Components of Cells

• Elements: Pure substances composed of only one type of atom.
• Ions: Charged atoms or groups of atoms.
• Polymers: Large molecules made up of repeating units (monomers).
• Monomers: Small units that form polymers.
• Covalent bonding: Strong bonds formed by sharing electrons.
• Ionic bonding: Strong bonds formed by transferring electrons.
• Polar molecules: Molecules with uneven charge distribution.
• Capillary action: Movement of water against gravity through narrow tubes.
• Carbohydrates: Organic molecules composed of carbon, hydrogen, and oxygen (CH2O)
• Monosaccharides: Single sugar molecule, example Glucose.
• Disaccharides: Two monosaccharides joined by a glycosidic bond, examples: Maltose, Sucrose, Lactose
• Polysaccharides: Many monosaccharides joined; examples: Starch, Glycogen, Cellulose
• Reducing sugars: Can donate electrons, and are tested using Benedict's reagent.
• Benedict's reagent: Alkaline copper(II) sulphate solution for testing reducing sugars.
• Iodine test: Potassium iodide solution, detects the presence of Starch.
• Colorimetry: Measuring the absorption of light using a spectrophotometer.
• Lipids: Nonpolar macromolecules, including fats, oils, and phospholipids.
• Triglycerides: Made of one glycerol molecule and three fatty acids.
• Fatty acids: Long-chain carboxylic acids.
• Saturated: Fatty acids without double bonds.
• Unsaturated: Fatty acid with double bonds.
• Phospholipids: Modified triglycerides with a phosphate group.
• Hydrophobic: Repelled by water.
• Hydrophilic: Attracted to water.
• Surfactants: Compounds that lower water surface tension.
• Sterols: Lipids forming ring structures, including cholesterol.
• Emulsion test: Laboratory test for lipids using ethanol.
• Peptides: Chains of two or more amino acids.
• Amino acids: Building blocks of proteins.
• Proteins: One or more polypeptides arranged into a complex macromolecule.
• R-group: Variable side chains of amino acids defining their properties.
• Peptide bond: Bond between two amino acids.
• Polypeptide: Chain of three or more amino acids.