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Section 2 - Cells - Coggle Diagram

- - - - Structures and functions
        
        Rough endoplasmic reticulum - protein synthesis and transport
        
        Smooth endoplasmic reticulum - lipid / carbohydrate synthesis
        
        Vacuole (plants) - contain sugars / amino acids
        
        Golgi apparatus and vesicles - modifies and transports molecules
        
        Chloroplasts (plants and algae) - for photosynthesis
        
        Mitochondria - site of respiration
        
        Lysosomes - removes bacteria and dead cells / material
        
        Cell membrane - regulates passage of substances into cells
        
        Cell wall (plants, algae, fungi) - mechanical strength
        
        Cellulose
        
        Nucleus - contains protein-bound, linear DNA
        
        80S Ribosomes - protein synthesis
    - - Capsid coat
      - Contain nucleic acids (DNA or RNA)
      - Extremely small
        
        Viruses range from 20-300nm
      - Lipid envelope or attachment proteins
      - Acellular and non-living
    - - Non membrane-bound organelles
      - Much smaller than eukaryotic cells
        
        Bacterial cells range from 0.1-10 um
      - Structures and functions
        
        70S Ribosomes
        
        Prokaryotic ribosomes are smaller than eukaryotic ribosomes
        
        Cell wall containing murein (peptidoglycan)
        
        Cell membrane
        
        Plasmids - small strands of DNA
        
        May contain genes for antibiotic resistance
        
        Capsule - prevents phagocytosis
        
        Flagella - for mobility
        
        Circular DNA, no associated proteins, no nucleus
  - - - Cold, isotonic, buffered solution
        
        Cold = reduce enzyme activity
        
        Isotonic - prevent organelles shrinking / bursting
        
        pH buffer - prevent protein denaturation
      - Magnification = (size of image) / (size of real object)
        
        Image = appearance in the microscope
      - Using light rays and lenses to magnify images
      - Light rays can distinguish between objects 0.2 um apart
        
        0.2 um is the resolution / resolving power
        
        Resolution / resolving power = distance between objects that allows the to be seen as 2 objects
    - - Transmission electron microscope (TEM)
        
        Can see through specimen
        
        Thin section
        
        Flat, 2D image
        
        Specimen must be in a vacuum
        
        Artefacts
      - Scanning electron microscope (SEM)
        
        Less resolving power than TEM
        
        3D image
        
        May use false-colour
        
        Artefacts
        
        Specimen must be in a vacuum
      - Electron microscopes have much better resolving power (nm)
    - - Ultracentrifugation
        
        Re-spin supernatant
        
        Heaviest organelles in the pellet
        
        Nuclei and mitochondria
      - Cell broken up, organelles removed
        
        Homogenisation
        
        Allows us to study organelles
  - - - Produces 2 daughter cells with the same number of chromosomes as the parent cell
      - Interphase
        
        Cell is not dividing in interphase
        
        DNA replication occurs
        
        G1, S, and G2 phases
      - Prophase
        
        Metaphase
        
        Anaphase
        
        Telophase
        
        Cytokinesis
        
        IPMATC
      - Prophase
        
        Chromosomes visible, spindle fibres develop
      - Metaphase
        
        Chromosomes align down equator of cell, spindles attach to centromere
      - Anaphase
        
        Spindle fibres separate the chromatids; they move towards opposite poles of cell
      - Telophase
        
        Chromosomes become chromatin, nuclear envelope forms
      - Cytokinesis
        
        Cytoplasm divides, two separate cells form
      - Cell returns to interphase, cell cycle repeats
    - - Produces 4 daughter cells, each with half the number of chromosomes as the parent cell
    - - Bacteria
        
        Binary fission
        
        Replication of DNA and plasmids
        
        Cytoplasm divides to form 2 daughter cells
      - Viruses
        
        No cell division (as acellular)
        
        Host cell machinery replicates viral components
        
        Viruses inject genetic material into host cells
- - - - Causes an immune response
    - - Pathogens
      - Cells from another membrane of same species
      - Toxins
      - Abnormal body cells e.g. cancer cells
  - - - Within body fluids
      - B cell with antibody specific for antigen presents foreign antigen on cell surface
        
        Helper T cell with specific receptor binds to B cell
        
        Clonal expansion of B cells
        
        Plasma B cells produce secrete antibodies
        
        Memory B cells
        
        One B cell produces one type of antibody
        
        Monoclonal antibodies
        
        1 more item...
        
        Divide rapidly upon re-infection and become plasma cells
        
        Basis of active vaccination
    - - Within cells
      - Antigen-presenting cells
        
        Helper T cells have receptors specific for the antigen
        
        Activation and clonal expansion
        
        Stimulates cytotoxic T cells, B cells, and phagocytes
        
        Cytotoxic cells kill infected or abnormal cells
  - - - Phagocytes = type of white blood cell
      - Chemoattractants from pathogens or abnormal cells
        
        Phagocytes recognise the pathogen and ingest it
        
        Phagosome
        
        Lysosomes release lysozymes into the phagosome
        
        Phagolysosome
        
        Pathogen is hydrolysed
        
        Contents are released (exocytosis) or absorbed
- - - - Bilayer
      - Hydrophilic heads and hydrophobic tails
        
        Allows lipid-soluble molecules to enter
      - Flexible
        
        Fluid-mosaic model
    - - Embedded throughout
        
        Fluid-mosaic model
      - Span either across whole membrane or part of it
      - Mechanical support
      - Channels, carrier proteins
      - Receptors
      - Adhesion
    - - Adds strength / rigidity to membrane
      - Restricts movement of other membrane molecules
    - - Help stabilise the membrane
      - Receptors (glycoproteins)
      - Attachment of cells
      - Recognition sites
        
        Important for lymphocytes and immune function
  - - - Small, non-polar, lipid-soluble molecules only
      - Down concentration gradient
    - - Down concentration gradient
      - Protein channels
        
        Ions
      - Carrier proteins
        
        Glucose
    - - Movement of water
        
        High water potential to low
    - - Absorption of glucose and amino acids with sodium ions
        
        Carrier proteins
        
        Uses sodium ion concentration gradient