Please enable JavaScript.

Coggle requires JavaScript to display documents.

Cells (2), image, image, image - Coggle Diagram

- - - - structure = small fluid-filled sac in the cytoplasm, surrounded by membrane and produced by Golgi apparatus
      - function = stores lipids & proteins made, transports out of cell
  - - - walls of small intestine contain villi -> increase S.A for absorption
        
        contain folds called microvilli that further increase S.A
        
        lots of mitochondria to provide energy for absorption
- - - - use attachment proteins to bind to complementary receptor proteins on surface of host cells
      - attachment proteins are unique and require different receptor proteins on host cells - some viruses can only infect 1 type of cells as a result
      - not alive so dont undergo cell division, instead they inject DNA/RNA into host cell and cell replicates viral particles
- - - - phagocytosis
    - - antibodies bind to antigens to form antibody-antigen complexes
  - - - each variable region has a unique tertiary structure
- - - - phospholipid molecules form a continuous bilayer
        
        fluid as phospholipids are constantly moving
        
        head is hydrophilic (attracts water)
        
        tail is hydrophobic (repels water)
        
        center of bilayer is hydrophobic and membrane doesn't allow water soluble substances through it
      - cholesterol molecules give the bilayer rigidity
        
        restrict movement of phospholipids
      - proteins scattered throughout bilayer "like a mosaic" including channel proteins & carrier proteins & receptor proteins
        
        some can move sideways and others are fixed
      - glycoproteins & glycolipids
    - - below 0 = phospholipids have no energy, cannot move, rigid membrane. channel/carrier proteins deform (inc. permeability) ice crystals also from that piece membrane (inc. permeability)
      - between 0-45 = phospholipids are fluid, membrane partially permeable. as temp inc. phospholipids move more as they have more energy (inc. permeabililty)
      - above 45 = phospholipid bilayer starts to melt (inc. permeability) water in cell expands, puts pressure on membrane. channel/carrier proteins deform cannot control entry & exit (inc. permeability)
  - - - larger molecules = diffuse very slowly through phospholipid bilayer
      - charged particles = diffuse slowly as they're water soluble & centre of bilayer is hydrophobic
      - uses carrier proteins & channel proteins to carry molecules across the CSM
      - passive process
      - carrier proteins
        
        move large particles across membranes
        
        different proteins facilitate movement of different particles
        
        large molecule attaches to a carrier protein in membrane
        
        protein changes shape
        
        molecules is released on opposite side of membrane
      - channel proteins
        
        form pores in membrane for charged particles to diffuse through
        
        different channel proteins facilitate movement of different particles
      - factors affecting diffusion
        
        conc. gradient = higher gradient, faster rate
        
        no. of carrier/channel proteins = the greater the number of proteins, the faster the rate of diffusion
    - - conc. gradient = higher it is, the faster the rate of diffusion -> slows down over time
      - thickness of exchange surface = thinner surface, the shorter the diffusion distance -> faster rate
      - surface area = larger surface area, the faster the rate
  - - - water potential gradient = higher water potential, the faster the rate
      - thickness of exchange surface = the thinner the surface, the faster the rate
      - surface area = larger surface area, faster rate
  - - - active transport moves solutes from low -> high conc.
      - facilitated diffusion moves solutes from high -> low conc
      - active transport requires energy, facilitated diffusion does not
    - - type of carrier proteins
      - bind 2 molecules at once
      - the conc gradient of 1 molecule is used to move the other molecules against it's own conc gradient
    - - speed of individual carrier proteins = faster they work, faster rate
      - no. of carrier proteins = the more proteins, the faster rate
      - rate of respiration in cell & ATP availability = inhibited respiration, no active transport
    - - glucose absorbed into bloodstream in small intestine
      - in the ileum, conc. of glucose too low for it to diffuse into blood, so glucose absorbed into lumen of ileum via active transport
      - Na+ actively transported in/out of epithelial cells into blood via NaK pump -> creates conc. gradient
      - causes Na+ to diffuse lumen -> epithelial cell down conc. gradient via Na-glucose co-transporter protein
      - co-transporter carries glucose into cell with Na, conc of glucose in cell increases
      - glucose diffuses out of cell into blood, down conc. gradient via protein channel (facilitated diffusion)
- - - - oral = less effective as molecules may be too larger to be absorbed into blood
- - - - HIV antigen bound to bottom of well in a well plate
      - sample of blood plasma added to well, any HIV antibodies will bind to HIV antigen stuck to bottom of well - then washed to remove unbound antibodies
      - a secondary antibody with a specific enzyme attached is added to the well, can bind to HIV antibody & well is washed out to remove any unbound secondary antibody
      - a solution is added to the well containing a substrate, can react with enzyme attached to 2nd antibody and form a coloured solution. if solution changes colour, patient has HIV antibodies and is positive for HIV
- - - - G1 = cell grows, new organelles & proteins are made
      - S = cell replicates DNA, ready to divide via mitosis
      - G2 = cell keeps growing & proteins needed for division are made
  - - - designed to control the rate of cell division in tumour cells by disrupting the cell cycle
      - dont distinguish normal cells from cancer cells so healthy cells die as a result also
      - G1 (cell growth & protein production) = chemotherapy prevents synthesis of enzymes needed for DNA replication. cell cannot enter the S phase and is forced to kill itself (apoptosis)
      - S phase (DNA replication) = radiation & some drugs damage DNA, at several points of cell cycle the cell is checked for damage, if too severe the cell will kill itself - preventing further tumour growth
- - - - AIDS = condition where immune system deteriorates & eventually fails
    - - spherical
      - core = contains genetic material (RNA) & some proteins (reverse transcriptase) needed for virus replication
      - capsid = outer coating of protein
      - envelope = extra outer layer made of membrane stolen from CSM of previous host cell
      - attachment protein = stick out from envelope, help HIV attach to host Th cell
    - - attachment protein attaches to receptor molecule on cell membrane of host Th cell
      - capsid released into cell, uncoats & releases RNA into cells cytoplasm
      - inside cell, reverse transcriptase makes complementary strand of DNA from viral RNA template
      - double stranded DNA is made & inserted into human DNA
      - viral proteins assembled into new viruses which bud from cell & go on to infect other cells
      - latency period = when HIV drops after initial infection to lower level, no symptoms felt for years
- - - - how much bigger the image is than the specimen you are observing
    - - use light to form an image
      - max resolution of 0.2 micrometres
      - max useful magnification is x1500
    - - use electrons to form an image
      - higher resolution than optical microscopes
        
        max resolution = 0.0002 micrometres
      - max useful magnification is x1,500,000
      - transmission electron microscopes
        
        use electromagnets to focus beam of electrons through specimen
        
        denser parts of specimen absorb more electrons and appear darker
        
        give high resolution images so internal structure of organelles can be seen
        
        can only be used on very thin specimens and performed in a vacuum so specimen must be dead
      - scanning electron microscope
        
        scan a beam of electrons across specimen, knocks off electrons from specimen and collects them in a cathode ray tube to form an image
        
        images show surface of specimen and can be 3D
        
        can be used on thick specimens
        
        give lower res images than TEMs
  - - - place cells in a homogeniser, breaks up plasma membrane and release organelles into a solution
      - solution must be ice cold = reduce activity of enzymes
      - solution must be isotonic = same conc. as cells being broken down, to prevent damage to organelles via osmosis
      - buffer solution must be added to maintain pH
    - - homogenised cell solution filtered through gauze to separate any cell debris
    - - cell fragments poured into tube & put into centrifuge, spun at low speed. heaviest organelles (nuclei) fall to bottom and form a pellet, organelles suspended in fluid above pellet (supernatant)
      - supernatant filtered off and put into separate tube, spun in centrifuge at higher speed, heaviest organelle (mitochondria) form pellet again
      - process repeated at higher speeds until all organelles are spirited out