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Tour Of The Cell Chapter 6 Microscopy What is the difference between magnification and resolving power? Magnification is how much larger the object can now appear Resolving power is the ability to distinguish between two points It is limited by the wavelength of visible light The different microscopes Light microscope - resolving power is limited by the wavelengths of light Specimen should be stained, but can be alive ◦ compound microscope ◦ stereomicroscope Electron microscope - resolving power is greater since wavelengths of electrons are smaller than those of light ◦ SEM - 3D image ◦ TEM - flat image electron microscopes cannot use live specimens How did scientists first discover the different cell parts? As organisms get larger, why do they become multicellular? It’s all about the surface area to volume ratio! Prokaryotic vs. Eukaryotic Cells Prokaryotic cells Bacteria, Archaea genetic material not in a nucleus no membrane bound organelles Eukaryotic cells Protists, Plants, Fungi and Animals true nucleus with genetic material has membrane bound organelles The Prokaryotic Cell The Plasma Membrane General Eukaryotic Cells Two Areas of the Eukaryotic Cell What is the space between the cell membrane and the nucleus called? The cytoplasm. This includes the organelles and the cytosol The cytosol is the fluid medium found in the cytoplasm The nucleus Nuclear Components Envelope = double layered membrane that has pores for molecular transport Chromatin = DNA + protein complex of threadlike fibers that make up the eukaryotic chromosome Chromosome = Chromatin fibers condense into visible chromosomes during cell division Ribosomes • Prokaryotic ribosomes differ from eukaryotic ribosomes • Function = Site of protein synthesis The Endomembrane system Related through direct continuity or by transfer on membrane segments through vesicles Structure of membranes is not identical Includes: Nuclear envelope --> Endoplasmic reticulum --> Golgi apparatus --> lysosomes --> vacuoles -->plasma membrane Transport vesicle from ER New vesicle forming Transport vesicle from Golgi Functions of Golgi apparatus Modifies stores and routes products of ER Alters membrane phospholipids Targets products for parts of the cell Vacuoles Larger than vesicles food vacuoles = formed by phagocytosis contractile vacuole = found in fresh water protozoans, keeps water balance central vacuole = found in most plant cells stores organic compounds, has enzymes to break macromolecules, has poisonous and unpalatable compounds, etc. Mitochondria and Chloroplasts not part of endomembrane system their membrane proteins are made by free ribosomes and their own ribosomes both have small amount of DNA grow and reproduce on their own within the cell involved in energy transformation Plastids amyloplasts - store starch, in roots and tubers chromoplasts - non-chlorophyll pigments responsible for non-green colors chloroplasts - chlorophyll containing plastids Peroxisome Contains enzymes that transfer hydrogen from substrates to oxygen producing hydrogen peroxide Some use oxygen to fuel the breakdown of fatty acids to smaller molecules that can be used in the mitochondrion In liver they detoxify alcohol and other poisons by transferring hydrogen from poison to oxygen Hydrogen peroxide is toxic. What enzyme can be used to break this down? Cytoskeleton Provides structural support Functions in motility and motion Microtubules cellular support provides tracks for movement within the cell: e.g. transport vesicles composes cilia and flagella, locomotive appendages of certain cells separation of chromosomes during cell division (spindle fiber) composes centrioles in animal cells Microfilaments smaller than microtublues participates in muscle contraction support localized cell contractions The Cell Surface cell walls in plant cells membrane linked channel plasmodesmata that connects cytoplasm between cells Animal Cell Surfaces glycocalyx - strengthens cell surface, helps glue animal cells together tight junctions - holds cells together to block transport desmosomes - rivets cells together into strong sheets but permits transport gap junctions - analogous to plasmodesmata in plant cells Let’s Review Name the cell structure and its function Be able to tell if this structure is found in prokaryote, eukaryote, plant and/or animal cells