Cells

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  • Created by: farahh24
  • Created on: 05-09-18 15:35
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  • Cells
    • Organelles
      • Nucleus
        • contains genetic information in the form of DNA molecules
        • double membrane, including pores that allow mRNA to escape
        • has nucleolus within - produces ribosomes
      • REM and SEM
        • Smooth endoplasmic reticulum - fat synthesis and storage
        • Rough endoplasmic reticulum - has ribosomes bound to surface, synthesis and transport of proteins
      • Golgi apparatus
        • compact structure of cisternae, modifies proteins.
      • Cytoskeleton
        • Microfilament - contractile fibres with actin protein. Responsible for cell contraction in cytokinesis
        • Microtubules - globular tubulin proteins, form tubes that form scaffold-like structure determining shape of cell. Form spindle fibres
        • Intermediate fibres - maintain integrity of cells
      • Centrioles
        • Composed of microtubules, form centrosome, involved in organisation of spindle fibres
    • Plant-exclusive organelles
      • Cell wall
        • Made of cellulose, permeable, rigid to maintain cell structure
      • Vacuoles
        • membrane-lined sacs, maintain water potential, store nutrients, selectively permeable
      • Chloroplasts
        • Responsible for photosynthesis, double membrane. Contain chlorophyll
          • Fluid enclosed is stroma.  Flattened sacs are thylokoid. Thylokoids stacked together are granum. Grana are joined by membranes called lamellae.
    • Difference between prokaryotic and eukaryotic cells
      • Ribosomes
        • Prokaryotic: 70S Eukaryotic: 80S
      • DNA
        • Prokaryotic: single chromosome, circular DNA supercoiled, no nucleus. Extra chromosomal DNA in plasmids.
        • Eukaryotic: linear DNA in nucleus, extra chromosomal DNA present only in certain organelles, e.g. chloroplasts, mitochondria
      • Prokaryotic: unicellular. Eukaryotic: unicellular or multicellular
      • Cell wall
        • Prokaryotic: peptidoglycan
        • Eukaryotic: chitin, cellulose or not present
  • QUESTIONS
    • DNA organisation? prokaryotic: proteins fold and condense DNA. Eukaryotic: associated with proteins called histones

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