Cell Membrane and Organelles

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  1. The Cell Theory: 3 Conditions
    • Cells are the basic units of structure and function in all living things
    • They are capable of carrying out all necessary activities for life
    • All new cells come from pre-existing cells
  2. Plasma Membrane: Function
    regulates the passage of material in and out of the cell
  3. Fluid Mosaic Model
    Semi permeable membrane consists of a double layer of phospholipids
  4. Phospholipid Bi-layer
    Plasma membrane consists of hydrophilic polar heads and hydrophobic non polar tailsImage Upload
  5. Glycolipids
    ganglioside related in the transmission of electrical impulses and cell to cell recgonition
  6. Membrane proteins
    Usually have carbohydrate groups attached to them, therefore plasma membrane is super rich

    membrane spanning proteins have regions that are hydrophilic and hydrophobic

    protein can attach internally or through one days

    • regions that cross into hydrophobic layer is usually alpha helices
    • spiral formation minimizes contact with polar ends
  7. Transmembrance proteins
    • are involved in carrying materials across the membrane
    • cell recgonitions
    • cell adhesion
    • cell signaling
    • enzymatic reactions

    • proteins of this type can be pores for ions
    • may open or close in response to external signals
  8. Glycocalx
    • describes the protein carbohydrate rich coating on cell surface
    • sugars are exclusively outside
  9. Main factors if molecule can pass through membrane are:
    • size
    • charge/polarity
    • generally fastest is small and non polar because interior is very hydrophobic
    • polar molecules can get through with the assistance of spanning proteins
  10. Diffusion
    • From high concentration to low concentration
    • happens without any input energy
    • especially with small non polar molecules (CO2 oxygen, water)
  11. Osmosis
    • Diffusion of water
    • moves from high water concentrations to low concentration
    • moves from low solute to high solute concentraions
  12. IsotonicHypertonic and Hypotonic
    • same solute, molecules are not stagnant but are still moving back and forth, there is just no net movement
    • high solute
    • low solute
  13. Facilitated Diffusion
    • passive transport involves use of channel and carrier proteins to allow molecules to diffuse down a gradient
    • molecules that may not be able to get through plasma membrane on their own
    • opening of ion channels favors the input of positive charge particles because the cytoplasm is naturally negatively charge
  14. Active gradient
    • Transport against gradient requires input energy
    • ATPase pumps are found in every cell and are important in keeping up gradient changes (especially in nerve cells)
  15. Sodium Potassium pumps
    • ATP is used to pull 2K+ ions into cell while pushing 3 Na ions out (maintains negative charge)
    • Helps control the solute concentration within the cytoplasm of cells
    • therefore preventing cells from shrinking or swelling too much from extracellular environment changes i.e. hyper/hypotonic
  16. Antiport
    pump that pulls two molecules in oposite directions
  17. Symport
    Pump that pulls two molecules in same direction
  18. Uniport
    Pump that pulls molecules in the one direction
  19. Calcium Pumps
    • Ca2+ is kept in low concentrations in cytoplasm but in high concentration in the ER
    • Pump is embeded in the ER membrane and pumps Ca from the cytoplasm into the ER lumen
  20. Endocytosis
    Cell membrane pinches inward and forms a pocket around large molecules and brings them into cell
  21. Exocytosis
    Vesicle contained material is expelled and the carrying vesicle merges with the cell membrance
  22. Cell Junctions
    Hold cells together so that they form complex tissues
  23. Occluding Junctions or Tight Junctions
    • Seal spaces between cells
    • proteins that tightly wind between cells binding the cells together
    • Useful in places where things or nutrients are absorbed in only one side of the cell but not the other
  24. Anchoring Junctions/Desmosomes
    • Connect one cells cytoplasm to another via anchoring proteins
    • Occur between cells that increase stress from shearing forces or contracting forces
    • Also allow cells to contract themselves into tublike tissues as actin filaments contract
    • Cytoplasms are linked but no material exchange occures
    • ex: heart cells
  25. Communications or Gap Junctions
    • Allow cells to directly exchange cytoplasmic material vis channels that cross both membranes
    • Formed by connecting proteins which build tubes between two adjacent cells
    • These tubes pass ions and material between cells
    • Therefore, allowing for rapid transit of chemical and electrical signals
    • Allows for rapid and complex movements
    • Ex: fishtail flips
  26. Plasmodesmata
    Plant cel equivalent of gap junctions
  27. Eukaryotic Cells
    • Fungi
    • Protists
    • Plants
    • Animals
    • Have cell bound organelles, allows for compartmentalization of activities
    • More efficient because can do many functions at once
  28. Nucleus
    • DNA storage
    • Nuclear envelope is a double membrane with large pores for communication
  29. Chromosomes
    DNA genome complexed into structural proteins
  30. Histones
    Proteins that package large strands of DNA into limited space of nucleus
  31. Nucleolus
    • Not surrounded by membrane
    • Dense structure where RNA synthesis occurs
  32. Ribsomes
    • Involved in protein production (translation)
    • They are not organelles
    • Have two subunits, one large and one small each composedof rRNA (ribsomal RNA) and proteins
    • Found free in cytoplasm or bound to the ER
    • Free Ribosome synthesize proteins that wil stay in cytoplasm
    • Bound ribosomes translate proteins that will be secreted by cell or are for membranes
  33. Endoplasmic Reticulum
    • Network of membrane enclosed spaces in cytoplasm
    • Interrior is called lumen
    • At certain points lumen is continuous with nuclear envelope
  34. Smooth ER
    is involved with lipid synthesis and detox of drugs and poisons
  35. Rough ER
    Involved in protein synthesis
  36. Golgi Apparatus
    • Stack of membrane enclosed sacs between the ER and plasma membrane
    • Vesicles containing newly synthesized proteins bud off ER and fuse with beginning of Golgi body
    • Golgi packages and modifies proteins before their final destination in the cell
  37. Lysosomes
    • Contain hydrolytic enzymes that break down proteins nucleic acids, and carbs
    • They aid in renewing a cells own components by breaking down and realeasing molecule building blocks into cytoplasm for reuse
    • Very acidic, pH-5
  38. Peroxisomes
    • Contain oxidative enzymes that catalyze reactions in which H2O2 is produced and degraded
    • Breakdown fats into small molecules 
    • Detoxify compounds such as alcohol
  39. Mitochondria
    • Site or aerobic respiration and energy production
    • outer and inner phospholipid bilayer membrane
    • outer membrane has many pores and acts as a sieve allowing molecules through based on size 
    • Between membrane layers is the inner membrane space
    • Have their own DNA and can divide on their own similar to prokaryote
  40. Cristea
    • Folds in inner membrance soace
    • includes proteins of electron transport chain
  41. Matrix
    • is inside inner membrane 
    • Krebs cycle/Citric Acid cycle
    • ATP production
  42. Endosymbiotic Hypothesis
    Mitochondria was engulfed or phagocytosis by cell and became symbiont
  43. Centrioles
    • Involved in cell division
    • Help with spatial arrangement in cell
    • Make up centresomes
  44. Receptor mediated Endocytosis
    • Involved the use of protein recports located on the surface of the plasma membrane
    • the substance that is brought into the cells attaches to a receptor on surface called a coated pit
    • The membrane pinches off and brings the molecule in in a coated vesicle
  45. Clathrin
    • Coated pit in plasma membrane
    • They are coated on the intracellular side with the protein Clathrin
  46. Cilia and Flagella
    • Thin hairlike structures that extend from the cell membrane of soem eukaryotic cells and produce movement
    • Ciliary motion is used to push fluids across their membranes
    • Both are used for movement
    • Cilia occur in large concentrations, while Flagella occur alone
  47. Axoneme
    • Regular backbone of linked microflaments
    • Make up a 9+2 arrangement
    • Two central microtubles are surround by 9 anchoring microtubles
  48. Basal Body
    Cylindrial structure made up of nine sets of triplet microtubles that are arranged in a circle
Card Set:
Cell Membrane and Organelles
2013-07-14 05:01:20
Biology GRE

Biology GRE
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