Bio 130 Exam 2

  1. All cells have these
    Plasma Membranes
  2. The Plasma membrane model is referred to as?
    A Fluid Mosaic model
  3. The plasma membrane is considered a mosaic of?
    Lipids, proteins, and carbs.
  4. What is the purpose of the plasma membrane?
    Cell-signaling, allow things to pass and exit. Semi-permiable.
  5. What is the extracellular environment?
    outside the cell
  6. What is the cytosol enviroment?
    Inside the cell
  7. What is the main body of the plasma membrane made of?
  8. What are the protein recognitions sites on the Plasma membrane?
  9. This protein spans all the way through the membrane from one side to the other.
    Integral Membrane Protein
  10. Phospholipids are amphipathic molecules. What does that mean?
    It has both Mydrophboic and hydrophilic parts
  11. The two leaflets of the plasma memb. are?
  12. What are the two types of Integral or intrinsic membrane proteins?
    Transmembrane proteins and Lipid-anchored proteins.
  13. These proteins have regions that are physically embedded in the hydrophobic portion of the phopholipid bilayer
    Transmembrane proteins.
  14. For these proteins an amino acid of the protein is covalently attached to a lipid.
    Lipid-anchored protein
  15. These proteins are noncovalently bound either to integral membrane proteins that project out from the membrande or to a polar head groups of phospholipids.
    Peripheral or extrinsic membrane proteins
  16. Approx how many of all genes encode transmembrane proteins?
  17. Plasma membrane are important for ?
    Medical and biological studies
  18. These can be used to predict the number if transmembrane proteins.
    Computer programs
  19. Is the trend of 20-30% gene encoding true for all facets of life?
  20. How do you view the plasma membranes?
    With a Transmission Electron Microscope or freesz fracture electron microscopy
  21. The sample is thin sectioned and stained with heavey metal dyes. These dyes bind tightly to the polar head groups but not the fatty acyl chains. This makes the membranes resemble railroad tracks
    Transmission electron microscopy (TEM)
  22. specialized form of TEM used to analyze the interior of the phospholipid bilayer. Samples frozen in liquid N and fracurted w/ a knife. the leaflets fracture into the P face (inside) and the Eface (outside). can provide significant details about the membrane protein
    Freeze Fracture Electron Microscopy (FFEM)
  23. Most lipids can rotate freely around their long axes and move laterally within the membrane leaflet, thus membranes are concidered?
  24. But “flip-flop” of lipids from one leaflet to the opposite leaflet does not occur spontaneously. what is needed to move the lipids
  25. What does flippase require to move lipids?
  26. Certain lipids associate strongly w/ eacgother to form what?
    lipid rafts
  27. These lipid rafts have some differences than the rest of the membrane.
    Have a high concentration of cholesterol and unique set of membrane proteins
  28. What are the factors that effect fluidity of te plasma membrane?
    Length of fatty acyl tails, presence of double bonds, and the presence of cholesterol
  29. How does the length of fatty acyl tails effect fluidity?
    shorter tails are less likely to interact which makes it less fluid like
  30. how does the presence of double bonds effect the fluidity of plasma membranes.
    The double bonds creat kinks in the fatty acyl tail, making it more difficult for neighboring tails to interact.
  31. How does the presence of cholesterol make the membrane less fluid like?
    It stabilizes the membranes but is effected by temp.
  32. What ass the name of the experiments on lateral movements done in 1970?
    Larry Frye and Michael Edidin experiment.
  33. Not all integral membrane proteins can move. depending on the cell tupe what percent are restricked in their movement?
  34. What are the Integral membrane proteins may be bound to that restrict proteins from moving laterally.
  35. Membrane proteins may be also attached to molecules that are outside the cell, such as the interconnected network of proteins that forms the
    Extracellular matrix
  36. In Eukaryotes what systems work together to synthesize lipids?
    Cytosol and endomembrane
  37. These are made via enzymes in cytosol or taken into cells from food.
    Fatty acid building blocks
  38. Where does the processing of the fatty acid process occur?
    At cystosolic leaflet of the Smooth ER
  39. How are lipids transfed?
    Via vesicles
  40. How do the lipids in the ER diffuse to the nuclear envelope?
    They diffuse laterally
  41. Where are lipids transpoted?
    To the Golgi, lysosomes, vacuoles, or plasma membrane
  42. these extract lipid from one membrane for insertion in another.
    Lipid exchange proteins.
  43. Except for proteins destined for semiautonomous organelles, most transmembrane proteins are directed to?
    the ER membrane 1st
  44. From the ER, membrane proteins can be transferred via _____ to other membranes of the cell
  45. This is the process of covalently attaching carbohydrate to a protein or lipid.
  46. Carbohydrate to lipid
  47. Carbohydrate to protein
  48. These can serve as a recognition signals for other cellular proteins. Play a role in cell surface recognition and helps protect proteins from damage
  49. These are Glycosylation that have an attachment of carbohydrate to nitrogen atom of asparagine side chain
    N-linked Glycosylation
  50. These are glycosylation that have addition of sugars to O2 atom of serine or threonine side chains. Occurs only in Golgi
    o-linked glycosylation
  51. Since the membrane is selectively poermeable only some ions and molecules can pass through. This ensures that?
    Essential molecules enter, Metabolic intermediates remain, and waste products exit
  52. What are the ways to move across the membranes?
    Passive and Active Transport
  53. Passive Transport can be broken down into two types:
    Passive diffusion and facilitated diffusion
  54. No energy: Diffusion of solute through a membrane w/o transport protein
    Passive diffusion
  55. No energy: Diffusion of a solute through a membrane w/ the aide of a transport protein.
    Facilitated diffusion
  56. This requires energy - up or gainst gradient.
    Active transport
  57. Barrier to hydrophilic molecules and ions due to
    hydrophobic interior
  58. Rate of diffusion depends on?
    Chemistry of solute and its concentration
  59. Diethylurea diffuses______ faster through the bilayer than urea, due to nonpolar ethyl groups
    50 times
  60. Living cells maintain a relatively constant internal environment different from their external environment. What are the two types?
    Transmembrane gradient and ion electochemical gradient
  61. Equal water and solute concentrations on either side of the membrane
  62. Solute concentration is higher (and water concentration lower) on one side of the membrane
  63. Solute concentration is lower (and water concentration higher) on one side of the membrane
  64. Water diffuses through a membrane from an area with more water to an area with less water
  65. If the solutes cannot move, water movement can make the cell ____ as water enters or leaves the cell.
    Shrink or swell
  66. the tendency for water to move into any cell
    Osmotic pressure
  67. How do cells maintain their size and shape?
    Maitianing balance between extracellular and intracellular solute concentrations
  68. shrinkage of a cell in a hypertonic solution
  69. swelling and bursting of a cell in a hypotonic solution
    Osmotic lysis
  70. What prevents mahjor changes in cell size?
    Cell Wall
  71. pushes plasma membrane against cell wall
    Turgor Pressure
  72. – plants wilting because water leaves plant cells
  73. Freshwater protists like Paramecium have to survive in a strongly hypotonic environmene. To prevent osmotic lysis, _______ take up water and discharge it outside the cell
    Contractile Vacuoles Maintains constant cell volume
  74. are transmembrane proteins that provide a passageway for the movement of ions and hydrophilic molecules across membranes
    Transport proteins
  75. There are two classes of transport proteins based of type of movement
    Channels and Transporters
  76. Form an open passageway for the direct diffusion of ions or molecules across the membrane. Most are gated
  77. Name an example of a Channel transport protein
  78. Also known as carriers Conformational change transports solute across membrane. Principal pathway for uptake of organic molecules, such as sugars, amino acids, and nucleotides
    Transporter Transport protein
  79. Transporter of single molecule or ion
  80. Transporter of two or more ions or molecules transported in same direction
    Symporter or cotransporter
  81. Transporter of Two or more ions or molecules transported in opposite directions
  82. Movement of a solute across a membrane against its gradient from a region of low concentration to higher concentration. Energetically unfavorable and requires the input of energy
    Active Transpot
  83. Active transport that uses a pump. Directly uses energy to transport solute
    Primary active transport
  84. Active Transport that uses a different gradient.? Uses a pre-existing gradient to drive transport
    Secondary active transport
  85. Actively transports Na+ and K+ against their gradients using the energy from ATP hydrolysis
  86. Na+/K+-ATPase 3 Na+ are exported for every
    2 K+ imported into cell
  87. exports one net positive (+) charge
    Electrogenic pump
  88. Used to transport large molecules such as proteins and polysaccharides
  89. Material inside the cell packaged into vesicles and excreted into the extracellular medium. Plasma membrane invaginates (folds inward) to form a vesicle that brings substances into the cell
  90. Three types of endocytosis:
    Receptor-mediated endocytosis, Pinocytosis, Phagocytosis
  91. ability to promote change or do work
  92. Energy associate with movement
  93. Energy due to location or structure
  94. Chemical energy, the energy in molecular bonds, is a form of
    Potential energy
  95. 1st law of thermodynamics
    “Law of conservation of energy” Energy cannot be created or destroyed,
  96. Second Law of Thermodynamics
    Transfer of energy from one form to another increases the entropy (degree of disorder) of a system
  97. What happens as entorphy increases in organisms?
    There will be less energy available to promote change.
  98. Total energy is?
    Usable energy + Unusable energy
  99. Energy transformations involve an increase in
    entropy (disorder that cannot be harnessed to do work)
  100. Amount of energy available to do work
    Free energy (G) aka Gibbs free energy
  101. What is the formula for GIbbs free energy?
  102. what do the symblos mean in Gibbs free energy equation?
    H= Enthalpy ot total engery, G= Free energy or amount of energy for work, S=Entropy or unusable energy, and T=absolute temperature in K
  103. Gibbs free energy reactions facts?
    Spontaneous, occur w/o additional energy, and cane be slow.
  104. What is the key factor of the free energy change?
    if ?G is negative, then process is exergonic and spontaneous
  105. What is the formula for the free energy change?
    ?G = ? H – T ? S
  106. ?G<0 (negative free energy change)
    Exergonic = spontaneous and energy is released
  107. ?G>0 (positive free energy change)
    Endergonic = not spontaneous and ? Requires addition of energy to drive reaction
  108. What do cells use to drive rxns?
    ATP hydolysis
  109. Can an endergonic rxn be coupled to an exergonic rxn?
  110. give an example of a coupled rxn.
    Glucose +ATP -> Glucose-6-phosphate +ADP
  111. Since spontaneous rxns are not fast what do they need to spped up?
    Catalysts and enzymes
  112. an agent that speeds up the rate of a chemical reaction without being consumed during the reaction
  113. protein catalysts in living cells
  114. RNA molecules with catalytic properties
    Activation Energy
  115. Initial input of energy to start reaction. Allows molecules to get close enough to cause bond rearrangement. Can now achieve transition state where bonds are stretched
    Activation Energy
  116. What are some Common ways to overcome activation energy?
    Large amounts of heat and/or using enzymes to lower activating energy
  117. location where reaction takes place
    Active site
  118. reactants that bind to active site
  119. formed when enzyme and substrate bind
    Enzyme-substrate complex
  120. Substrate binding. Enzymes have a high specificity for their substrate
    Lock and Key metaphor
  121. THis phenomenon in substrate binding that is an interaction also involves conformational changes
    Induced fit phenomenon
  122. What are the two inhibition types?
    Competitive and noncompetitive
  123. Molecule binds to active site. Inhibits ability of substrate to bind – more substrate needed
    Competitive inhibition
  124. Inhibitor binds to allosteric site, not active site
    noncompetitive inhibition
  125. What are some other requirments for enzymes?
    Prosthetic groups, cofactor, and coenzyme
  126. molecules permanently attached to the enzyme
    Posthetic groups
  127. usually inorganic ion that temporarily binds to enzyme
  128. usually inorganic ion that temporarily binds to enzyme
  129. Enzymes are effect by the environment. What is the biggest factor?
    pH and Temperature. Usually have a narrow window
  130. is found in all living organisms, and involved in cleaving tRNA molecules
    Ribonuclease P (RNase P)
  131. Chemical rxns occur in _____ and each step is coordinated by a specific _____.
    Metabolic pathway. Enzyme
  132. These pathways are exergonic and breakdown cellular components. These also are used for recycling building blocks.
    Catabolic pathways
  133. These pathways are Endergonic, Synthesis cellular components, and must be coupled to exergonic rxn.
    Anabolic pathways
  134. How is energy stored?
    It is stored as ATP, NADH
  135. What are the two ways to make ATP?
    Substrate-level phosphorylation and Chemiosmosis
  136. Enzyme directly transfers phosphate from one molecule to another molecu
    Substrate-level phosphorylation
  137. Energy stored in an electrochemical gradient is used to make ATP from ADP and Pi
  138. rxn where Electron removed from one molecule is added to another
    Redox rxn
  139. removal of electrons
  140. addition of electrons
  141. NAD+ means?
    Nicotinamide adenine dinucleotide
  142. NADH is useful intwo ways:
    Releases a lot of energy when oxidized that can be used to make ATP and can donate electrons during synthesis rxns to energize them.
  143. Make large macromolecules or smaller molecules not available from food. Require energy inputs from intermediates (NADH or ATP) to drive reactions. Regulation of metabolic pathways
    Biosynthetic rxns
  144. This turns genes on and off
    Gene regulation
  145. Cell-signalling pathways like hormones
    Cellular regulation
  146. Feedback inhibition – product of pathway inhibits early steps to prevent over accumulation of product
    Biochemical regulation
  147. Most lar molecules exist for a relatively short period of time. What is their breakdown called?
  148. time it takes for 50% of the molecules to be broken down and recycled
  149. All living organisms must efficiently use and recycle organic molecules. Expression of genome allows cells to respond to changes in their environment. How is this done?
    RNA and proteins are made when needed and then broken down when they are not.
  150. mRNA degradation important. How so?
    Conserve energy by degrading mRNAs for proteins no longer required and remove faulty copies of mRNA.
  151. mRNA degradation takes place two ways:
    Exonucleases and exosome
  152. mRNA degradation where enzymes cleave off nucleotides from end.
  153. mRNA degradation where multiprotein complex uses exonucleases
  154. A large complex that breaks down proteins using protease enzymes. these Proteases cleave bonds between amino acids
  155. This tags target proteins to the proteasome to be broken down and recycled
  156. Ubiquitin tagging allows the cell to:
    degrade improperly folded proteins and rapidly degrade proteins to respond to changing cell conditions.
  157. Lysosomes contain ______ to break down proteins, carbohydrates, nucleic acids, and lipids
  158. How do lysosomes take up digested substances?
  159. Recyling worn out organelles using an autophagosome
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Bio 130 Exam 2