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Cell structure review, ribosomes made in nucleolus - Coggle Diagram

- - - - plasma membrane
      - might have cell wall
      - both have ribosomes
    - - eukaryotes don't always have cell wall (animals)
      - cell walls are made of different stuff
      - different size ribosomes
        
        prokaryotes - 70S
        eukaryotes - 80S
      - eukaryotes have membranous organelles
        prokaryotes don't
      - prokaryotic cells are smaller
        
        eukaryotes = 10-100µm
        prokaryotes = 0.1-10µm
      - prokaryotes have circular DNA
        eukaryotes have linear DNA
      - might have different organelles
        (e.g. prokaryotes may have slime capsule, mesosomes, simple flagellum
        eukaryotes may have microvilli, chloroplasts, complex flagellum, etc.)
      - different cell division
        
        prokaryotes use binary fission
        eukaryotes use asexual or sexual reproduction
    - - eukaryotic organelles at work
        
        protein synthesis, transportation and secretion
        
        proteins made in ribosomes
        
        proteins from ribosomes on RER
        
        RER releases them in vesicles
        
        sent to Golgi body
        
        1 more item...
        
        proteins from free ribosomes
        
        stay in cell
        
        cytoskeleton
        
        microtubules
        
        25nm
        
        maintain cell shape
        
        provide transport system (movement of organelles)
        
        aid in cell division (pull chromosomes apart)
        
        can move cells (cilia & flagella)
        
        intermediate filaments
        
        8-12nm
        
        maintain cell shape
        
        act as anchors for immobile organelles
        
        microfilaments
        
        7nm
        
        maintain cell shape
        
        change cell shape (muscle contraction or movement of cells)
        
        can help things move inside cells (create a current within cytoplasm
        
        aids in cell division (forms cleavage burrow to split cytoplasm)
      - can be membranous
        
        nucleus
        
        largest organelle
        
        surrounded by a nuclear envelope with nuclear pores to let stuff out
        
        contains the chromatin network and the nucleolus
        
        contains nearly of the the cell's genetic material
        
        chromatin consists of DNA and proteins and becomes chromosomes when cell divides
        
        nucleolus makes RNA and ribosomes
        
        endoplasmic reticulum
        
        smooth
        
        involved in making lipids
        
        no ribosomes
        
        rough ER
        
        studded with ribosomes
        
        transported proteins made on its attached ribosomes
        
        series of flattened membranous sacs called cisternae
        
        continuous with outer nuclear envelope
        
        Golgi apparatus/body
        
        stack of membranous flattened sacs
        
        may be multiple in a cell
        
        constantly changing structure
        
        modifies and packages proteins from the ER into vesicles
        
        mitochondria
        
        spherical or sausage-shaped
        
        have two membranes separated by fluid filled space
        
        highly folded inner membrane forms cristae
        
        central part is called matrix
        
        site of aerobic respiration and ATP (adenosine triphosphate) production
        
        chloroplasts
        
        only found in plant cells and some protoctists
        
        two membranes
        
        has flattened membrane sacs called thylakoids inside
        
        stack of thylakoids is called a granum (pl. grana)
        
        often contains starch grains
        
        site of photosynthesis
        
        lysosomes
        
        spherical sacs with a single membrane
        
        contain powerful digestive enzymes and used to break stuff down
        
        vacuole
        
        large central organelle of plant cells
        
        filled with water and solutes and pushes cytoplasm against cell wall
        
        makes cell turgid
        
        vesicles
        
        membrane-bound sacs
        
        carry different substances round the cell
      - can be non-membranous
        
        ribosomes
        
        tiny
        
        found in cytoplasm as well as bound to ER
        
        made up of two subunits
        
        site of protein synthesis
        
        centrioles
        
        small tubes of protein fibres (microtubules)
        
        pair next to nucleus in animal cells and in cells of some protoctists
        
        take part in cell division
        
        form spindles which move chromosomes
        
        cilia & flagella
        (undulipodia)
        
        hair-like extensions which stick out from the cell surface
        
        cylinder which contains 9 microtubules in a circle and 2 microtubules in a central bundle
        
        move using energy from ATP
        
        longer versions move entire cell
        shorter versions move substances by sweeping
        
        cytoskeleton
        
        network of protein fibres inside a cell
        
        microtubules
        
        microfilaments
        
        intermediate filaments
        
        proteins include actin and tubulin
        
        provides internal framework
        
        helps give structure and shape to cell
        
        used to move organelles around
        
        plant cell wall
        
        outside plant cell plasma membranes
        
        made of cellulose strands that form a sieve-like network
        
        very strong
        
        supports the cell
  - - - more than one cell
      - two types
        
        simple
        
        chain of identical cells
        
        e.g. spirogyra
        
        complex
        
        groups of different types of cells
        
        e.g. humans
    - - single-celled
      - e.g. diatom or amoeba
  - - - named cells after the rooms of monks in 1660s
    - - developed cell theory in 1840
- - - - developed in 1931
      - highest magnification = x2,000,000
      - highest resolution = 0.2nm
      - higher magnification and resolution
      - very expensive
      - large and immobile
      - can only be used in a carefully controlled environment
      - samples must be dead
      - images are black and white
      - colour can be added after
      - electron beam can damage samples (more artefacts)
      - complex preparation leads to artefacts
      - transmission electron microscopy
        
        samples are set in resin, cut ultra-thin and stained again
        
        heavy salts used for staining give contrast because electrons cannot pass through where they've collected
        
        beam of electrons is passed through the specimen and focused using electromagnetic lenses
        
        magnification = x500,000 - x2,000,000
        
        resolution = 0.2-0.5nm
      - scanning electron microscopy
        
        magnification = x100,000 - x500,000
        
        resolution = 3-10nm
        
        samples are stained with heavy metals and sprayed at an angle (metal shadowing) to enhance contrast
        
        beam of "primary" electrons is passed of surface using electromagnetic lenses
        
        "secondary" electrons emitted from the sample are collected
        
        3D image can be produced
    - - highest resolution = 200nm
      - highest magnification = x2,000
      - lower magnification & resolution than EM
      - compound light microscopy
        
        glass lenses are used to direct light through a sample and pick up a magnified image
        
        little or no prep needed
        
        less risk of artefacts than with EM
        
        relatively inexpensive
        
        small and portable
        
        little training needed
        
        available to many
        
        natural colour can be observed
        
        living tissue can be observed
        
        magnification = x40 - x1,000
        
        resolution ≤ 200nm
      - laser scanning confocal microscopy
        
        magnification = x1,000
        
        resolution ≤ 200nm
        
        a specimen is dyed with a fluorescent chemical and a laser is moved across the specimen
        the emitted light is picked up (only from close to the focal place)
        
        images are retrieved point-by-point and reconstructed by a computer
        
        a beam splitter is used as the light rays of the laser and the fluorescent light have the same path and focal plane
        the beam splitter used is a dichroic mirror which reflects only one wavelength and lets others through
        
        2D and 3D images can be made
        
        living tissue can be observed
        
        depth of field can be controlled
        
        background information can be reduced
        
        gives sharp images
        
        expensive
  - - - get sample of cell
        
        place on slide
        
        put drop of water on slide
        
        place cover slip on top
        
        should trap water and sample under it
    - - place drop of stain (e.g. iodine) next to cover slip
        
        put piece of blotter on other side of cover slip
        
        water should be drawn out and absorbed by blotter and stain should be drawn in to replace it