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TOPIC 1 CELL BIOLOGY. - Coggle Diagram

- - - - living things undertake essential chemical reactions
    - - living things are responsive to internal and external stimuli
    - - living things maintain a stable internal environment
    - - living things can move and change shape or size
    - - living things produce offspring, either sexually or asexually
    - - living things exhibit the removal of waste products
    - - living things exchange materials and gases with the environment
- - - - contain hundreds of nuclei
    - - can grow to 100mm, only contain a single nucleus
    - - consist of hyphae, long undivided sections of hypha which contain many nuclei
  - - - cells removed from tissues can survive independently for short periods of time
      - nothing smaller than a call has been found to be able to live independently
      - experiments have demonstrated that cells cannot grow in sealed and sterile conditions
- - - - can form any cell type, as well as extra embryonic tissue
    - - can form any cell type
    - - can differentiate into a number of closely related cell types
    - - can not differentiate, but are capable of self renewal
  - - - they can continuously divide and replicate
    - - they have the capacity to differentiate into specialised cell types
  - - - using multipotent adult tissue is effective for some conditions but limited in scope of application
      - stem cells derived from umbilical cord blood need to be stored and preserved at cost, raising issues of availability and access
      - the greatest yield of pluripotent stem cells comes from embryos, but requires the destruction of a potential living organism
    - - Stargardt's macular dystrophy
        
        genetic, causes progressive vision loss to the point of blindness
        
        treated by replacing dead cells in the retina with functioning ones derived from stem cells
      - Leukemia
        
        bone marrow transplants for cancer patients who are immunocompromised as a result of chemotherapy
- - - - internal fluid component of the cell
    - - region of the cytoplasm where the DNA is located
    - - autonomous circular DNA molecules that may be transferred between bacteria
    - - complexes of RNA and protein that are responsible for polypeptide synthesis
    - - semi-permeable and selective barrier surrounding the cell
    - - rigid outer covering made of peptidoglycan; maintains shape and prevents bursting
    - - a thick polysaccharide layer used for protection against dessication
    - - long, slender projections containing a motor protein that enables movement
    - - hair-like extensions that enable adherence to surfaces (attachment pili) or mediate bacterial conjugation (sex pili)
  - - - nucleus
      - mitochondria
      - golgi apparatus
      - endoplasmic reticulum
      - ribosomes
    - - vacuole
      - chloroplasts
      - cell wall
- - - - net movement of molecules from a region of high concentration to a region of low concentration
      - passive
      - small and non-polar (lipophilic) molecules will be able to freely diffuse across cell membranes (e.g. O2, CO2, glycerol)
    - - passive movement of molecules across the cell membrane via the aid of a membrane protein
      - mediated by channel proteins and carrier proteins
        
        channel proteins
        
        only move molecules along a concentration gradient
        
        much faster rate of transport than carrier proteins
        
        carrier proteins
        
        may move molecules against concentration gradients in the presence of ATP
        
        much slower rate of transport than channel proteins
    - - net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached)
    - - uses energy to move molecules against a concentration gradient
  - - - polar hydrophilic phosphate head
      - two non-polar hydrophobic fatty acid tails
      - bilayer is held together by weak hydrophobic interactions between the tails
    - - integral proteins
        
        permanently attached to the membrane and are typically transmembrane
      - peripheral proteins
        
        temporarily attached by non-covalent interactions and associate with one surface of the membrane
    - - fluid – the phospholipid bilayer is viscous and individual phospholipids can move position
      - mosaic – the phospholipid bilayer is embedded with proteins, resulting in a mosaic of components
    - - two layers of protein flanked a central phospholipid bilayer
      - freeze-fracture electron micrographs showed transmembrane proteins, falsifying this model and coming up with the fluid mosaic model