Biology unit 2

  • Created by: rach555
  • Created on: 19-05-18 15:51
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  • Unit 2
    • Microscope
      • Mag= Image / Actual
      • Resolution- the power to distinguish two objects which are close in distance
      • Magnification- how many times bigger the image is compared to the object
      • Cell fractionation
        • Cold- reduce enzyme activity
        • Isotonic- prevent organelles bursting
        • Buffered- so pH doesn't fluctuate
        • 1.Homogenat-ion= homogeniser breaks up cells. Homogenate is filtered to remove debris
        • Ultracentrifug-ation
          • 1. Homogenate is spun at low speed so lightest organelles are put to bottom
          • 2.Sediment removed and supernant is spun again
          • 3. Supernant spun at higher speed until organelles sepe
    • Eukaryotes
      • Nucleus
      • Mitochondria
        • Double membrane, inner forms cristae
        • Cristae provide large surface area
        • Matrix contains proteins, lipids, ribosomes and DNA
        • Site of aerobic respiration. Produce ATP
      • Endoplasmic reticulum
        • Rough- ribosomes on surface
          • Large surface area for protein and glycoprotein synthesis
          • Pathway for transport
        • Smooth- no ribosomes
          • Synthesise, store and transport lipids
          • Synthesise, store and transport carbohydrates
      • Golgi apparatus
        • Made of stacks called cisternae
        • Have small vesicles
        • Function
          • Add carbohydrate to proteins to make glycoproteins
          • Produce secretory enzymes
          • Secrete carbohydrates
          • Transport, modify and store lipids
          • Form lysosomes
      • Lysosomes
        • Hydrolyse material engested by phagocyte
        • Digest worn out organelles
        • Break down dead cells
      • Ribosomes
        • Site of protein synthesis
        • 80S size
      • Plants
        • Chloroplasts
        • Vacuoles
        • Cell wall
    • Prokaryotes
      • Circular DNA- no nucleus
        • Used for replication of cells
      • Capsule
        • Protects bacterium and sticks bacteria
      • Cell-surface membrane
        • Selectively permeable layer to control entry and exit of chemicals
      • Cell wall- murein
        • Physical barrier stopping certain substances
      • Plasmid
        • Possesses genes that aid survival
      • Ribsomes
        • 70S
        • Site of protein synthesis
      • May have flagella which help swimming
    • Cell cycle
    • Immune system
    • Transport
      • Diffusion
        • Movement of molecules (small and non-polar)
        • High  to low concentration (down conc gradient)
      • Osmosis
        • Water moves from high to low water potential
        • Down water potential gradient
        • Through aqueous pores
        • Pure water has potential of zero (high WP). Lower WP is more negative e.g.-30
        • Animal cells
          • High water outside so water enters
            • Cell swells and bursts
          • Low water outside so water leaves
            • Cell shrinks
        • Plant cells
          • High water outside so water enters
            • Cells swells and becomes turgid
            • Cell doesn't burst due to cell wall strength
          • Low water outside so water leaves
            • Cell shrinks and becomes plasmolysed
            • Cytoplasm membrane pulls away from cell wall
      • Active transport
        • Molecules and ions
        • Uses ATP to change shape of carrier protein
        • Uses carrier proteins
        • Low to high concentration (against conc gradient)
        • Used for co-transport
      • Co-transport
        • 1.Sodium ions actively transported out of epithelial cells into blood
        • 2.High conc of sodium ions in lumen. Low in the E cells
        • 3.Sodium ions diffuse into E cells from lumen
        • 4.Glucose moves with it by facilitated diffusion
      • Facilitated diffusion
        • Charged ions and polar molecules
        • Protein channels and carrier proteins
        • Down concentration gradient
    • Cell division
      • Mitosis
        • 1.Prophase- chromosomes become visible. Centrioles go to opposite poles and develop spindle fibres. Nuclear envelope disappears
        • 2.Metaphase- spindle fibres attach to centromere and chromosomes are lined up along equator
        • 3.Anaphase- Centromeres divide and spindle fibres pull chromatids apart
        • 4.Telophase- nuclear envelope reforms and spindle disappears
        • 5.Cytokinesis- cytoplasm divides
        • Importance
          • Growth
          • Repair
          • Reproduction
      • Prokaryotic cells- binary fission
        • 1. Circular DNA replicates and attaches to different ends of cell membrane
        • 2. Plasmids replicate
        • 3. Cell membrane grows between DNA and divides cytoplasm
        • 4. New cell wall forma and divides cell
      • Viruses
        • 1.Attach to host cell by attachment proteins
        • 2.Inject nucleic acid into host cell
        • 3.Nucleic acid has genetic info that provides instructions
        • 4.Instrucftions for producing viral components, nucleic acid, enzymes and structural proteins
    • Viruses
      • Acellular and non-living
      • Capsid
      • Contain nucleic acids
      • Lipid ennvelope
      • Attachment proteins

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