Cell Structure and Cell Division

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  • Cell Structure and Division
    • Eukaryotes
      • complex
      • Animal
      • plant
        • cell wall
        • vacuole
        • chloroplast
          • site of photosynthesis
      • Algal
        • carry out photosynthesis
        • similar to plant cells
          • organelles tend to be different shapes/sizes to those in plants
            • e.g. large chloroplast
      • fungal cells
        • similar to plant cells
        • cell wall made of chitin
        • no chloroplast
    • Prokaryotes
      • single celled organisms
      • small
      • flagellum
        • rotates for movement
      • cell wall
        • murein
          • glycoprotein
      • capsules made of secreted slime
        • protects from immune system
      • plasmids
        • small loops of DNA
        • genes for antibiotic resistance
      • prokaryotic cell divsion
        • binary fission
        • 1. circular DNA (once) and plasmids replicate (many times)
        • 2. move to oppoiste poles
        • 3. cytoplasm divides
        • 4. 2 daughter cells created
    • Organelles
      • cell surface membrane
        • made of lipids and proteins
        • regulates movement of substances in and out of the cell
      • Nucleus
        • nuclear envelope
          • double membrane
        • nuclear pores
          • allow substances to move between nucleolus and cytoplasm
        • nucleolus
          • makes ribosomes
        • chromatin
          • contains chromosome
        • controls cells activities
          • e.g. transcription
      • mitochondrion
        • oval shaped
        • double membrane
        • inner membrane folded to form cristae
        • matrix
          • contains enzymes for respiration
        • site of aerobic respiration
          • produces ATP
      • chloroplast
        • small, flattened structure
        • double membrane
        • stacked membranes called thylakoids which form grana
          • grana and linked by lamellae
        • photosynthesis
      • Golgi Apparatus
        • fluid filled, membrane bound, flattened sacs
        • process and package proteins
        • makes lysosomes
        • Golgi vesicle
          • stores lipids and proteins made by golgi apparatus
          • small fluid filled sac in the cyroplasm
          • surrounded by a membrane
          • produced by golgi appparatus
          • lysosome
            • type of golgi vesicle
            • digestive enyme
      • ribosome
        • made of proteins and RNA
        • free floating or attached to RER
        • makes proteins
      • Rough endoplasmic reticulum
        • membranes enclosing fluid filled space
        • surface covered with ribosomes
        • folds and processes proteins made in ribosomes
      • smooth enddoplasmic reticulum
        • no ribosomes
        • synthesises and processes lipids
      • cell wall
        • supports cell and prevents it from changing shape
      • vaculole
        • membrane bound organelle filled with cell sap
          • sap - weak solution of sugar and salts
        • membrane - tonoplast
        • helps maintain presuure inside the cell and keep cell rigid
          • stops wilting
        • isolates unwanted chemicals
    • cells are adapted for their specific functions
      • lots of mitochondira
        • uses lots of energy
      • lots of ribosomes
        • makes lots of proteins
      • microvilli
        • increases surface area
        • increases absorption rate
      • red blood cells
        • have no nucleus to make more room for oxygen
    • virusus
      • acellular
      • nucleic acid surrounded by porotein
      • invade and reproduce inside host cells
      • protein coat called a capsid
      • attachment proteins
        • allow virus to cling onto suitable host cell
      • viral replication
        • 1. attach to host via receptor cells
        • 2. genetic material released into host cell
        • 3. genetic material replicated by host cell
        • 4. viral components assemble
        • 5. replicated viruses released from host cell
    • microscopes
      • magnification=image size/ actual size
      • resolution - the distance between 2 objects before they become 1
      • light microscope
        • preparing microscope slides
          • drop of water on slide
          • tweezers to place thin section of specimen onto water
          • drop of stain
          • cover slip
      • electron microscope
        • better resolution because electrons have shorter wavelengths
        • T(ransmission)EM
          • nonliving specimens
        • S(canning)EM
          • nonliving specimens
          • can use thick specimens
    • cell fractionation
      • 1.homogenisation
        • breaks up cell membrane
        • must be ice cold to reduce enzyme activity
        • must use a pH buffer
        • must be isotonic
      • 2. filtration
        • remove large debris
      • 3. ultracentrifugation
        • spin at high speeds
        • heaviest organelles form pellets
        • supernatent drained and repeat
    • Mitosis
      • interphase
        • normal functions carried out
        • preparation to divide
        • double genetic content
          • synthesis
        • organelles replicated
          • G1
        • ATP content increased
        • proteins needed for division created
          • G2
      • prophase
        • chromosomes condense
        • centrioles move to opposite ends forming spindles
        • nuclear envelope beaks down
      • 2 genetically identical daughter
      • Metaphase
        • chromosomes line up the middle of the cell and attach to spindle
      • Anaphase
        • centromeres divide, separating sister chromatids
        • chromatids pulled to opposite poles
      • Telophase
        • chromatids uncoil
        • nuclear envelope forms
        • cytokenesis
          • cytoplasm divides
            • 2 daughter cells are produced
      • chromosomes are made of 2 strands
    • cancer
      • mutations in genes which control mitosis
      • uncontrolled division
      • treatments
        • disrupt cell cycle
        • target rapidly dividng cells
      • cells form a tumour which invades surrounding tissue to form a cancer

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